@article {3083, title = {Realization of portable room temperature nanodiamond 13C hyperpolarizer}, year = {Submitted}, author = {A. Ajoy and R. Nazaryan and E. Druga and K. Liu and B. Han and J.T. Oon and M. Gierth and R. Tsang and J.H. Walton and C.A. Meriles and J.A. Reimer and D. Suter and A. Pines} } @article {3169, title = {Two-electron-spin ratchets as a platform for microwave-free dynamic nuclear polarization of arbitrary material targets}, journal = {Nano Letters}, year = {In Press}, author = {P.R. Zangara and J. Henshaw and D. Pagliero and A. Ajoy and J. Reimer and A. Pines and C. Meriles} } @article {3170, title = {Dynamics of frequency-swept nuclear spin optical pumping in powdered diamond at low magnetic fields}, journal = {Proceedings of the National Academy of Science}, year = {2019}, month = {01/2019}, abstract = {

A broad effort is underway to improve the sensitivity of NMR through the use of dynamic nuclear polarization. Nitrogen vacancy (NV) centers in diamond offer an appealing platform because these paramagnetic defects can be optically polarized efficiently at room temperature. However, work thus far has been mainly limited to single crystals, because most polarization transfer protocols are sensitive to misalignment between the NV and magnetic field axes. Here we study the spin dynamics of NV\−13C pairs in the simultaneous presence of optical excitation and microwave frequency sweeps at low magnetic fields. We show that a subtle interplay between illumination intensity, frequency sweep rate, and hyperfine coupling strength leads to efficient, sweep-direction-dependent 13C spin polarization over a broad range of orientations of the magnetic field. In particular, our results strongly suggest that finely tuned, moderately coupled nuclear spins are key to the hyperpolarization process, which makes this mechanism distinct from other known dynamic polarization channels. These findings pave the route to applications where powders are intrinsically advantageous, including the hyperpolarization of target fluids in contact with the diamond surface or the use of hyperpolarized particles as contrast agents for in vivo imaging.

}, issn = {0027-8424}, doi = { https://doi.org/10.1073/pnas.1811994116 }, url = {https://www.pnas.org/content/early/2019/01/23/1811994116}, author = {P.R. Zangara and S. Dhomkar and A. Ajoy and K. Liu and R. Nazaryan and D. Pagliero and D. Suter and J. Reimer and A. Pines and C. Meriles} } @article {3228, title = {Indirect Detection of Short-lived Hydride Intermediates of Iridium N-Heterocyclic Carbene Complexes via Chemical Exchange Saturation Transfer (CEST) Spectroscopy}, journal = {The Journal of Physical Chemistry C}, year = {2019}, month = {06/2019}, abstract = {

For the first time, chemical exchange saturation transfer (CEST) nuclear magnetic resonance (NMR) is utilized to study short-lived hydride intermediates in the catalytic cycle of an organometallic complex [Ir(IMes)(Py)3(H)2]Cl. These complexes are typically not observable by other NMR techniques because they are low concentrated and undergo reversible ligand exchange with the main complex. The intermediatecomplexes [Ir(Cl)(IMes)(Py)2(H)2] and [Ir(CD3OD)(IMes)(Py)2(H)2]are detected, assigned, and characterized in solution, in situ and at room temperature. Understanding the spin dynamics in these complexes is necessary for enhancing the performance of the nuclear spin hyperpolarization technique signal amplification by reversible exchange. By eliminating [Ir(Cl (IMes)(Py)2(H)2] and manipulating the spin system by radiofrequency irradiation, the nuclear spin singlet lifetime of the hydride protons was increased by more than an order of magnitude, from 2.2 \± 0.1 to 27.2 \± 1.2 s. Because of its simplicity and ability to unravel unobservable chemical species, the utilized CEST NMR approach has a large application potential for studying short-lived hydride intermediates incatalytic reactions.

}, doi = {https://doi.org/10.1021/acs.jpcc.9b04179}, url = {https://pubs.acs.org/doi/10.1021/acs.jpcc.9b04179$\#$}, author = {Stephan Knecht and Sara Hadjiali and Danila A Barskiy and Alexander Pines and Grit Sauer and Alexey Kiryutin and Konstantin Ivanov and Alexandra Yurkovskaya and Gerd Buntkowsky} } @article {3531, title = {Rotaxane probes for the detection of hydrogen peroxide by 129Xe hyperCEST NMR}, journal = {Angewandte Chemie International Edition}, year = {2019}, doi = {10.1002/anie.201903045}, url = {https://onlinelibrary.wiley.com/doi/full/10.1002/anie.201903045}, author = {Klass, Sarah H and Truxal, Ashley E and Fiala, T A and Kelly, Joseph and Nguyen, Dang and Finbloom, Joel A and Wemmer, David E and Pines, Alexander and Francis, Matthew B} } @article {3171, title = {Selective decoupling and Hamiltonian engineering in dipolar spin networks}, journal = {Physics Review Letters}, volume = {122}, year = {2019}, month = {01/2019}, abstract = {

We present a protocol to selectively decouple, recouple, and engineer effective interactions in mesoscopic dipolar spin networks. In particular, we develop a versatile protocol that relies upon magic angle spinning to perform Hamiltonian engineering. By using global control fields in conjunction with a local actuator, such as a diamond nitrogen vacancy center located in the vicinity of a nuclear spin network, both global and local control over the effective couplings can be achieved. We show that the resulting effective Hamiltonian can be well understood within a simple, intuitive geometric picture, and corroborate its validity by performing exact numerical simulations in few-body systems. Applications of our method are in the emerging fields of two-dimensional room temperature quantum simulators in diamond platforms, as well as in molecular magnet systems.

}, doi = {https://doi.org/10.1103/PhysRevLett.122.013205}, url = {https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.122.013205}, author = {A. Ajoy and U. Bissbort and D. Poletti and P. Cappellaro} } @article {3230, title = {Two-Electron-Spin Ratchets as a Platform for Microwave-Free Dynamic Nuclear Polarization of Arbitrary Material Targets}, journal = {Nano Letters}, year = {2019}, month = {03/2019}, abstract = {

Optically pumped color centers in semiconductor powders can potentially induce high levels of nuclear spin polarization in surrounding solids or fluids at or near ambient conditions, but complications stemming from the random orientation of the particles and the presence of unpolarized paramagnetic defects hinder the flow of polarization beyond the defect\’s host material. Here, we theoretically study the spin dynamics of interacting nitrogen-vacancy (NV) and substitutional nitrogen (P1) centers in diamond to show that outside protons spin-polarize efficiently upon a magnetic field sweep across the NV\–P1 level anticrossing. The process can be interpreted in terms of an NV\–P1 spin ratchet, whose handedness, and hence the sign of the resulting nuclear polarization, depends on the relative timing of the optical excitation pulse. Further, we find that the polarization transfer mechanism is robust to NV misalignment relative to the external magnetic field, and efficient over a broad range of electron\–electron and electron\–nuclear spin couplings, even if proxy spins feature short coherence or spin\–lattice relaxation times. Therefore, these results pave the route toward the dynamic nuclear polarization of arbitrary spin targets brought in proximity with a diamond powder under ambient conditions.

}, doi = {10.1021/acs.nanolett.8b05114}, url = {https://pubs.acs.org/doi/full/10.1021/acs.nanolett.8b05114}, author = {Pablo R. Zangara and J. Henshaw and Daniela Pagliero and Ashok Ajoy and Jeffrey A. Reimer and Alexander Pines and Carlos A. Meriles} } @article {2981, title = {Wide dynamic range magnetic field cycler: Harnessing quantum control at low and high fields}, journal = {Review of Scientific Instruments }, volume = {90}, year = {2019}, month = {01/2019}, abstract = {

We describe the construction of a fast field cycling device capable of sweeping a 4-order-of-magnitude range of magnetic fields, from \∼1 mT to 7 T, in under 700 ms, and which is further extendable to a 1 nT-7 T range. Central to this system is a high-speed sample shuttling mechanism between a superconducting magnet and a magnetic shield, with the capability to access arbitrary fields in between with high resolution. Our instrument serves as a versatile platform to harness the inherent dichotomy of spin dynamics on offer at low and high fields\—in particular, the low anisotropy, fast spin manipulation, and rapid entanglement growth at low field as well as the long spin lifetimes, spin specific control, and efficient inductive measurement possible at high fields. Exploiting these complementary capabilities in a single device opens up applications in a host of problems in quantum control, sensing, and information storage, besides in nuclear hyperpolarization, relaxometry, and imaging. In particular, in this paper, we focus on the ability of the device to enable low-field hyperpolarization of 13C nuclei in diamond via optically pumped electronic spins associated with nitrogen vacancy defect centers.

}, doi = {https://doi.org/10.1063/1.5064685}, url = {https://aip.scitation.org/doi/10.1063/1.5064685}, author = {A. Ajoy and X. Lv and E. Druga and K. Liu and B. Safvati and A. Morabe and M. Fenton and R. Nazaryan and S. Patel and T. Sjolander and J. Reimer and D Sakellariou and C. Meriles and A. Pines} } @article {3193, title = {Zero-Field Nuclear Magnetic Resonance of Chemically Exchanging Systems}, journal = {Nature Communications}, volume = {10}, year = {2019}, month = {07/2019}, abstract = {

Zero- to ultralow-field (ZULF) nuclear magnetic resonance (NMR) is an emerging tool for precision chemical analysis. In this work, we study dynamic processes and investigate the influence of chemical exchange on ZULF NMR J-spectra. We develop a computational approach that allows quantitative calculation of J-spectra in the presence of chemical exchange and apply it to study aqueous solutions of [15N]ammonium (15N) as a model system. We show that pH-dependent chemical exchange substantially affects the J-spectra and, in some cases, can lead to degradation and complete disappearance of the spectral features. To demonstrate potential applications of ZULF NMR for chemistry and biomedicine, we show a ZULF NMR spectrum of [2-13C]pyruvic acid hyperpolarized via dissolution dynamic nuclear polarization (dDNP). We foresee applications of affordable and scalable ZULF NMR coupled with hyperpolarization to study chemical exchange phenomena in vivo and in situations where high-field NMR detection is not possible to implement.

}, doi = {https://doi.org/10.1038/s41467-019-10787-9}, url = {https://www.nature.com/articles/s41467-019-10787-9?fbclid=IwAR1MB5nAamCMGynKRk0sjD6V8rTlZ329IvrVKrCwIO8QjrEH4wD23BV5gak}, author = {Danila Barskiy and Michael Tayler and Irene Marco-Rius and John Kurhanewicz and Daniel Vigneron and Sevil Cikrikci and Ayca Aydogdu and Moritz Reh and Andrey Pravdivtsev and Jan-Bernd H{\"o}vener and John Blanchard and Teng Wu and Dmitry Budker and Alexander Pines} } @article {2980, title = {Enhanced dynamic nuclear polarization via swept microwave frequency combs}, journal = {Proc. Natl. Acad. Sci}, year = {2018}, month = {10/2018}, abstract = {

Dynamic nuclear polarization (DNP) has enabled enormous gains in magnetic resonance signals and led to vastly accelerated NMR/MRI imaging and spectroscopy. Unlike conventional cw-techniques, DNP methods that exploit the full electron spectrum are appealing since they allow direct participation of all electrons in the hyperpolarization process. Such methods typically entail sweeps of microwave radiation over the broad electron linewidth to excite DNP but are often inefficient because the sweeps, constrained by adiabaticity requirements, are slow. In this paper, we develop a technique to overcome the DNP bottlenecks set by the slow sweeps, using a swept microwave frequency comb that increases the effective number of polarization transfer events while respecting adiabaticity constraints. This allows a multiplicative gain in DNP enhancement, scaling with the number of comb frequencies and limited only by the hyperfine-mediated electron linewidth. We demonstrate the technique for the optical hyperpolarization of 13C nuclei in powdered microdiamonds at low fields, increasing the DNP enhancement from 30 to 100 measured with respect to the thermal signal at 7T. For low concentrations of broad linewidth electron radicals [e.g., TEMPO ((2,2,6,6-tetramethylpiperidin-1-yl)oxyl)], these multiplicative gains could exceed an order of magnitude.

}, doi = {1807125115}, url = {https://doi.org/10.1073/pnas.1807125115}, author = {Ashok Ajoy and Kristina Liu and Xudong Lv and Raffi Nazaryan and G.Wang and E . Druga and Jeff Reimer and Ditter Suter and C. Ramanathan and C.A Meriles and Alexander Pines} } @article {3196, title = {Hyperpolarized NMR Spectroscopy: d-DNP, PHIP, and SABRE Techniques}, journal = {Chemistry - An Aisan Journal}, volume = {13}, year = {2018}, month = {08/2018}, abstract = {

The intensity of NMR signals can be enhanced by several orders of magnitude by using various techniques for the hyperpolarization of different molecules. Such approaches can overcome the main sensitivity challenges facing modern NMR/magnetic resonance imaging (MRI) techniques, whilst hyperpolarized fluids can also be used in a variety of applications in material science and biomedicine. This Focus Review considers the fundamentals of the preparation of hyperpolarized liquids and gases by using dissolution dynamic nuclear polarization (d-DNP) and parahydrogen-based techniques, such as signal amplification by reversible exchange (SABRE) and parahydrogen-induced polarization (PHIP), in both heterogeneous and homogeneous processes. The various new aspects in the formation and utilization of hyperpolarized fluids, along with the possibility of observing NMR signal enhancement, are described.

}, doi = {10.1002/asia.201800551}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/asia.201800551}, author = {Kirill Kovtunov and Ekaterina Pokochueva and Oleg Salnikov and Samuel Cousin and Dennis Kurzbach and Basile Vuichoud and Sami Jannin and Eduard Chekmenev and Boyd Goodson and Danila Barskiy and Igor Koptyug} } @article {2581, title = {Optically-pumped dynamic nuclear hyperpolarization in 13C enriched diamond}, journal = {Phys. Rev. B Rapid Communications}, year = {2018}, abstract = {

We investigate nuclear spin hyperpolarization from optically polarized nitrogen vacancy centers in isotopically enriched diamonds with 13C concentrations up to 100\%.\ 13C enrichment leads to hyperfine structure of the nitrogen vacancy electron spin resonance spectrum and dynamic nuclear polarization enhancement profile. We show that strongly-coupled \cthirt spins in the first shell surrounding a nitrogen vacancy center generate resolved hyperfine splittings, but do not act as an intermediary in the transfer of hyperpolarization of bulk nuclear spins. High levels of \cthirt enrichment are desirable to increase the efficiency of hyperpolarization for magnetic resonance signal enhancement, imaging contrast agents, and as a platform for quantum sensing and many-body physics.

}, url = {https://journals.aps.org/prb/accepted/0707cOeaT9fE2916845f0be02a174d447e77534ff}, author = {Parker, AJ and Jeong, K and Avalos, CE and Hausmann, BJM and Vassiliou, CC and Pines, A and King, JP} } @article {2979, title = {Orientation independent room-temperature optical 13C hyperpolarization in powdered diamond}, journal = {Science Advances}, volume = {4}, year = {2018}, month = {05/2018}, abstract = {

Dynamic nuclear polarization via contact with electronic spins has emerged as an attractive route to enhance the sensitivity of nuclear magnetic resonance beyond the traditional limits imposed by magnetic field strength and temperature. Among the various alternative implementations, the use of nitrogen vacancy (NV) centers in diamond\—a paramagnetic point defect whose spin can be optically polarized at room temperature\—has attracted widespread attention, but applications have been hampered by the need to align the NV axis with the external magnetic field. We overcome this hurdle through the combined use of continuous optical illumination and a microwave sweep over a broad frequency range. As a proof of principle, we demonstrate our approach using powdered diamond with which we attain bulk 13C spin polarization in excess of 0.25\% under ambient conditions. Remarkably, our technique acts efficiently on diamond crystals of all orientations and polarizes nuclear spins with a sign that depends exclusively on the direction of the microwave sweep. Our work paves the way toward the use of hyperpolarized diamond particles as imaging contrast agents for biosensing and, ultimately, for the hyperpolarization
of nuclear spins in arbitrary liquids brought in contact with their surface.

}, doi = {10.1126/sciadv.aar5492 }, url = {http://advances.sciencemag.org/content/4/5/eaar5492}, author = {Ashok Ajoy and Kristina Liu and Raff Nazaryan and Xudong Lv and Pablo R. Zangara and Benjamin Safvati and Guoqing Wang and Daniel Arnold and Grace Li and Arthur Lin and Priyanka Raghavan and Emanuel Druga and Siddharth Dhomkar and Daniela Pagliero and Jeffrey A. Reimer and Dieter Suter and Carlos A. Meriles and Alexander Pines} } @article {2963, title = {Rapid Catalyst Capture Enables Metal-Free para-Hydrogen-Based Hyperpolarized Contrast Agents}, journal = {The Journal of Physical Chemistry Letters}, volume = {9}, year = {2018}, month = {05/2018}, pages = {2721{\textendash}2724}, abstract = {

Hyperpolarization techniques based on the use of\ para-hydrogen provide orders of magnitude signal enhancement for magnetic resonance spectroscopy and imaging. The main drawback limiting widespread applicability of\ para-hydrogen-based techniques in biomedicine is the presence of organometallic compounds (the polarization transfer catalysts) in solution with hyperpolarized contrast agents. These catalysts are typically complexes of platinum-group metals, and their administration in vivo should be avoided. Herein, we show how extraction of a hyperpolarized compound from an organic phase to an aqueous phase combined with a rapid (less than 10 s) Ir-based catalyst capture by metal scavenging agents can produce pure\ para-hydrogen-based hyperpolarized contrast agents, as demonstrated by high-resolution nuclear magnetic resonance (NMR) spectroscopy and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The presented methodology enables fast and efficient means of producing pure hyperpolarized aqueous solutions for biomedical and other uses.

}, doi = {10.1021/acs.jpclett.8b01007}, url = {https://pubs.acs.org/doi/abs/10.1021/acs.jpclett.8b01007}, author = {Danila A Barskiy and Lucia A Ke and Xingyang Li and Vincent Stevenson and Nevin Widarman and Hao Zhang and Ashley Truxal and Alexander Pines} } @article {3195, title = {Selective Single-Site Pd-In Hydrogenation Catalyst for Production of Enhanced Magnetic Resonance Signals using Parahydrogen}, journal = {Chemistry - A European Journal}, volume = {24}, year = {2018}, month = {01/2018}, chapter = {2547}, abstract = {

Pd\−In/Al2O3\ single-site catalyst was able to show high selectivity (up to 98\ \%) in the gas phase semihydrogenation of propyne. Formation of intermetallic Pd\−In compound was studied by XPS during reduction of the catalyst. FTIR\−CO spectroscopy confirmed single-site nature of the intermetallic Pd\−In phase reduced at high temperature. Utilization of Pd\−In/Al2O3\ in semihydrogenation of propyne with parahydrogen allowed to produce \≈3400-fold NMR signal enhancement for reaction product propene (polarization=9.3\ \%), demonstrating the large contribution of pairwise hydrogen addition route. Significant signal enhancement as well as the high catalytic activity of the Pd\−In catalyst allowed to acquire\ 1H MR images of flowing hyperpolarized propene gas selectively for protons in CH, CH2\ and CH3\ groups. This observation is unique and can be easily transferred to the development of a useful MRI technique for an in situ investigation of selective semihydrogenation in catalytic reactors.

}, doi = {10.1002/chem.201705644}, url = {https://onlinelibrary.wiley.com/doi/full/10.1002/chem.201705644}, author = {Dudari Burueva and Kirill Kovtunov and Andrey Bukhtiyarov and Danila Barskiy and Igor Prosvirin and Igor Mashkovsky and Galina Baeva and Valerii Bukhtiyarov and Aleksandr Stakheev and Igor Koptyug} } @article {2421, title = {13C-Decoupled J-Coupling Spectroscopy Using Two-Dimensional Nuclear Magnetic Resonance at Zero-Field}, journal = {The Journal of Physical Chemistry Letters}, volume = {8}, year = {2017}, pages = {1512-1516}, author = {Sjolander, TF and Tayer, MCD and Kentner, A and Budker, D and Pines, A} } @article {2812, title = {Distance-dependent magnetic resonance tuning as a versatile MRI sensing platform for biological targets}, journal = {Nature Materials}, volume = {16}, year = {2017}, pages = {537 - 542}, chapter = {537}, author = {Choi, J.-S. and Kim, S. and Yoo, D. and Shin, T.-H. and Kim, H. and Gomes, M.D. and Kim, S. H. and Pines, A. and Cheon, J.} } @article {2699, title = {Invited Review Article: Instrumentation for nuclear magnetic resonance in zero and ultralow magnetic field}, journal = {Review of Scientific Instruments}, volume = {88}, year = {2017}, month = {09/2017}, abstract = {

We review experimental techniques in our laboratory for nuclear magnetic resonance (NMR) in zero and ultralow magnetic field (below 0.1 μT) where detection is based on a low-cost, non-cryogenic, spin-exchange relaxation free 87Rb atomic magnetometer. The typical sensitivity is 20-30 fT/Hz1/2 for signal frequencies below 1 kHz and NMR linewidths range from Hz all the way down to tens of mHz. These features enable precision measurements of chemically informative nuclear spin-spin couplings as well as nuclear spin precession in ultralow magnetic fields.

}, doi = {https://doi.org/10.1063/1.5003347}, url = {http://aip.scitation.org/doi/abs/10.1063/1.5003347}, author = {Tayler, MCD and Theis, Thomas and Tobias F. Sjolander and John W. Blanchard and Kentner, A and Pustelny, S and Pines, Alexander and Budker, Dmitry} } @article {2516, title = {Measuring molecular parity nonconservation using nuclear magnetic resonance spectroscopy}, journal = {ArXiv}, year = {2017}, author = {Eills, J and Blanchard, JW and Bougas, L and Kozlov, MG and Pines, A and Budker, D} } @article {2698, title = {Measuring molecular parity nonconservation using nuclear-magnetic-resonance spectroscopy}, journal = {Physical Review A}, volume = {96}, year = {2017}, month = {10/2017}, abstract = {

The weak interaction does not conserve parity and therefore induces energy shifts in chiral enantiomers that should in principle be detectable in molecular spectra. Unfortunately, the magnitude of the expected shifts are small and in spectra of a mixture of enantiomers, the energy shifts are not resolvable. We propose a nuclear-magnetic-resonance (NMR) experiment in which we titrate the chirality (enantiomeric excess) of a solvent and measure the diasteriomeric splitting in the spectra of a chiral solute in order to search for an anomalous offset due to parity nonconservation (PNC). We present a proof-of-principle experiment in which we search for PNC in the 13C resonances of small molecules, and use the 1H resonances, which are insensitive to PNC, as an internal reference. We set a constraint on molecular PNC in 13C chemical shifts at a level of 10\−5 ppm, and provide a discussion of important considerations in the search for molecular PNC using NMR spectroscopy.

}, doi = {https://doi.org/10.1103/PhysRevA.96.042119}, url = {https://journals.aps.org/pra/abstract/10.1103/PhysRevA.96.042119}, author = {John W. Blanchard and J. Ellis and Bougas, L and M. G. Kozlov and Alexander Pines and Dmitri Budker} } @article {2391, title = {An optimized microfabricated platform for the optical generation and detection of hyperpolarized 129Xe}, journal = {Scientific Reports }, year = {2017}, url = {http://www.nature.com/articles/srep43994}, author = {Daniel J. Kennedy and Scott J. Seltzer and Ricardo Jimenez-Martinez and Hattie L. Ring and Nicholas Malecek and Svenja Knappe and Elizabeth Donley and John Kitching and Vikram S. Bajaj and Alexander Pines} } @article {2580, title = {Understanding the magnetic resonance spectrum of nitrogen vacancy centers in an ensemble of randomly-oriented nanodiamonds}, journal = {J. Phys. Chem. C}, year = {2017}, author = {Jeong, K and Parker, AJ and Page, RH and Pines, A and Vassiliou, C and King, JP} } @article {1867, title = {129Xe NMR Relaxation-Based Macromolecular Sensing}, journal = {JACS Communication}, volume = {138}, year = {2016}, month = {07/2016}, chapter = {9747}, author = {Muller Gomes and Phuong Dao and Keunghong Jeong and Clancy Slack and Christophoros Vassiliou and Matthew B. Francis and David Wemmer and Alexander Pines} } @article {1955, title = {Nondisruptive Dissolution of Hyperpolarized 129Xe into Viscous Aqueous and Organic Liquid Crystalline Environments}, journal = {Angewandte Chemie }, year = {2016}, type = {Communication}, author = {AE Truxal and CC Slack and MD Gomes and CC Vassiliou and DE Wemmer and A Pines} } @article {2420, title = {Nuclear magnetic resonance at millitesla fields using a zero-field spectrometer}, journal = {Journal of Magnetic Resonance}, volume = {270}, year = {2016}, pages = {35-39}, author = {Tayler, MCD and Sjolander, TF and Pines, A and Budker, D} } @article {2297, title = {Rotaxane probes for protease detection by 129Xe hyperCEST NMR}, journal = {Chemical Communications}, year = {2016}, month = {12/2016}, doi = {10.1039/C6CC09302G}, author = {Slack, CS and Finbloom, JA and Jeong, K and Bruns, CJ and Wemmer, DE and Pines, A and Francis, MB} } @article {1941, title = {Rotaxane-mediated suppression and activation of cucurbit[6]uril for molecular detection by 129Xe hyperCEST NMR}, journal = {ChemComm}, year = {2016}, author = {Joel A. Finbloom and Clancy C. Slack and Carson J. Bruns and Keunhong Jeong and David E. Wemmer and Alexander Pines and Matthew B. Francis} } @article {2074, title = {Targeted Molecular Imaging of Cancer Cells using MS2-Based 129Xe NMR}, journal = {Bioconjugate Chemistry}, volume = {27}, year = {2016}, month = {07/2016}, chapter = {1796}, doi = {10.1021/acs.bioconjchem.6b00275}, url = {http://pubs.acs.org/doi/abs/10.1021/acs.bioconjchem.6b00275}, author = {Keunhong Jeong and Chawita Netirojjanakul and Henrik K Munch and Jinny Sun and Joel A Finbloom and David E Wemmer and Alexander Pines and Matthew B Francis} } @article {2070, title = {Transition-Selective Pulses in Zero-Field Nuclear Magnetic Resonance}, journal = {The Journal of Physical Chemistry}, volume = {120}, year = {2016}, month = {05/2016}, chapter = {4343}, doi = {10.1021/acs.jpca.6b04017}, url = {http://pubs.acs.org/doi/abs/10.1021/acs.jpca.6b04017}, author = {Sjolander, TF and Tayler, M and King, JP and Budker, D and Pines, A} } @article {1863, title = {Decoherence-protected transitions of nitrogen-vacancy centers in 99\% 13C-enriched diamond}, journal = {arXiv:1506.05484}, year = {2015}, month = {06/2015}, author = {Anna J. Parker and Hai-Jing Wang and Yiran Li and Alexander Pines and Jonathan P. King} } @article {1866, title = {Investigation of DOTA-Metal Chelation Effects on 129Xe Chemical Shift}, journal = {ChemPhysChem}, year = {2015}, author = {Keunhong Jeong and Clancy C. Slack and Christophoros C. Vassiliou and Phuong Dao and Muller D Gomes and Daniel J. Kennedy and Ashley E. Truxal and Lindsay J Sperling and Matthew B. Francis and David E. Wemmer and Alexander Pines} } @article {1924, title = {~Measurement of untruncated nuclear spin interactions via zero-to ultralow-field nuclear magnetic resonance}, journal = {Physical Review B}, year = {2015}, author = {John W. Blanchard and Tobias F. Sjolander and Jonathan P. King and Micah Ledbetter and Emma H. Levine and Vikram S. Bajaj and Dmitri Budker and Alexander Pines} } @article {1875, title = {Room temperature in situ nuclear spin hyperpolarization from optically pumped nitrogen vacancy centers in diamond}, journal = {Nature Communications}, year = {2015}, author = {Jonathan P. King and Keunhong Jeong and Christophoros C. Vassiliou and Chang S. Shin and Ralph H. Page and Claudia E. Avalos and Hai-Jing Wang and Alexander Pines} } @article {1627, title = {Zero-field nuclear magnetic resonance spectroscopy of viscous liquids}, journal = {Journal of Magnetic Resonance}, volume = {250}, year = {2015}, month = {01/2015}, pages = {1-6}, doi = {Doi:10.1016/j.jmr.2014.10.012}, author = {Shimizu, Y. and Blanchard, J.W. and Pustelny, S. and Saielli, G. and Bagno, A. and Ledbetter, M.P. and Budker, D. and Pines, A.} } @article {1474, title = {Genetically encoded reporters for hyperpolarized xenon MRI}, journal = {Nature Chemistry}, volume = {6}, year = {2014}, month = {04/2014}, pages = {629-634}, chapter = {629}, doi = {10.1038/nchem.1934 }, author = {Mikhail G. Shapiro and R. Matthew Ramirez and Lindsay J. Sperling and George Sun and Jinny Sun and Alexander Pines and David V. Schaffer and Vikram S. Bajaj} } @article {1598, title = {Gradient-free microfluidic flow labeling using thin magnetic films and remotely detected MRI (Cover Article)}, journal = {Journal of Magnetic Resonance}, volume = {249}, year = {2014}, month = {12/2014}, pages = {135-140}, author = {Halpern-Manners, N.W. and Kennedy, D.J. and Trease, D.R. and Teisseyre, T.Z. and Malecek, N.S. and Pines, A. and Bajaj, V.S.} } @article {1450, title = {Long-lived Heteronuclear Spin-Singlet States in Liquids at a Zero Magnetic Field}, journal = {Physical Review Letters}, volume = {112}, year = {2014}, pages = {077601}, chapter = {077601}, author = {Emondts, M. and Ledbetter, M. P. and Pustelny, S. and Theis, T. and Patton, B. and Blanchard, J. W. and Butler, M. C. and Budker, D. and Pines, A.} } @article {1451, title = {Molecular Sensing Using Hyperpolarized Xenon NMR Spectroscopy}, journal = {Israel Journal of Chemistry}, volume = {54}, year = {2014}, pages = {104-112}, doi = {10.1002/ijch.201300128}, author = {Palaniappan, K.K. and Francis, M.B. and Pines, A. and Wemmer, D.E.} } @article {1476, title = {Optically detected cross-relaxation spectroscopy of electron spins in diamonds}, journal = {Nature Communication}, volume = {5}, year = {2014}, month = {06/2014}, pages = {4135}, doi = {10.1038/ncomms5135}, author = {Wang, H. J. and Shin, C. S. and Seltzer, S. J. and Avalos, C. E. and Pines, A. and Bajaj, V. S.} } @article {1477, title = {Optically-detected nuclear quadrupolar interaction of 14N in nitrogen-vacancy centers in diamond}, journal = {Physical Review B}, volume = {89}, year = {2014}, pages = {205202}, doi = {10.1103/PhysRevB.89.205202}, author = {Shin, C. S. and Butler, M. C. and Wang, H. J. and Avalos, C. E. and Seltzer, S. J. and Liu, R. and Pines, A. and Bajaj, V.S.} } @article {1475, title = {Ultra-Low-Field NMR Relaxation and Diffusion Measurements Using an Optical Magnetometer (Cover Article)}, journal = {Angewandte Chemie}, volume = {53}, year = {2014}, month = {09/2014}, pages = {1-6}, doi = {DOI: 10.1002/anie.201403416}, author = {Ganssle, P. J. and Shin, H. D. and Seltzer, S. J. and Bajaj, V.S. and Ledbetter, M. P. and Budker, D. and Knappe, S. and Kitching, J. and Pines, A} } @article {1117, title = {Chemical analysis using J-coupling multiplets in zero-field NMR}, journal = {Chemical Physics Letters}, volume = {580}, year = {2013}, month = {08/2013}, pages = {160-165}, abstract = {

Zero-field nuclear magnetic resonance (NMR) spectroscopy is emerging as a new, potentially portable, and cost-effective NMR modality with the ability to provide information-rich, high-resolution spectra. We present simple rules for analysis of zero-field NMR spectra based on first-order perturbation theory and the addition of angular momenta. These rules allow for the prediction of observed spectral lines without numerical simulation. Results are presented for a few small organic molecules with characteristic spin topologies, demonstrating unambiguous assignment of peaks, highlighting the potential of zero-field NMR as a tool for chemical identification.

}, isbn = {0009-2614}, doi = {http://dx.doi.org/10.1016/j.cplett.2013.06.042}, url = {http://www.sciencedirect.com/science/article/pii/S0009261413008191}, author = {Theis, Thomas and Blanchard, John W. and Butler, Mark C. and Ledbetter, Micah P. and Budker, Dmitry and Pines, Alexander} } @article {245, title = {Fundamental Aspects of Parahydrogen Enhanced Low-Field Nuclear Magnetic Resonance}, journal = {Physical Review Letters}, volume = {110}, year = {2013}, note = {Phys Rev Lett113RITimes Cited:0Cited References Count:28}, month = {Mar 26}, pages = {137602}, abstract = {

We report new phenomena in low-field H-1 nuclear magnetic resonance (NMR) spectroscopy using parahydrogen induced polarization (PHIP), enabling determination of chemical shift differences, delta nu, and the scalar coupling constant J. NMR experiments performed with thermal polarization in millitesla magnetic fields do not allow the determination of scalar coupling constants for homonuclear coupled spins in the inverse weak coupling regime (delta nu \< J). We show here that low-field PHIP experiments in the inverse weak coupling regime enable the precise determination of delta nu and J. Furthermore we experimentally prove that observed splittings are related to delta nu in a nonlinear way. Naturally abundant C-13 and Si-29 isotopes lead to heteronuclear J-coupled H-1-multiplet lines with amplitudes significantly enhanced compared to the amplitudes for thermally prepolarized spins. PHIP-enhanced NMR in the millitesla regime allows us to measure characteristic NMR parameters in a single scan using samples containing rare spins in natural abundance. DOI: 10.1103/PhysRevLett.110.137602

}, keywords = {exchange}, isbn = {0031-9007}, doi = {Doi 10.1103/Physrevlett.110.137602}, url = {://WOS:000316685100032}, author = {Colell, J. and Turschmann, P. and Gloggler, S. and Schleker, P. and Theis, T. and Ledbetter, M. and Budker, D. and Pines, A. and Blumich, B. and Appelt, S.} } @article {247, title = {High-Resolution Zero-Field NMR J-Spectroscopy of Aromatic Compounds}, journal = {Journal of the American Chemical Society}, volume = {135}, year = {2013}, note = {J Am Chem Soc103RNTimes Cited:0Cited References Count:59}, month = {02/2013}, pages = {3607-3612}, abstract = {

We report the acquisition and interpretation of nuclear magnetic resonance (NMR) J-spectra at zero magnetic field for a series of benzene derivatives, demonstrating the analytical capabilities of zero-field NMR The zeroth-order spectral patterns do not overlap, which allows for straightforward determination of the spin interactions of substituent functional groups. Higher-order effects cause additional line splittings, revealing additional molecular information. We demonstrate resonance linewidths as narrow as 11 mHz, permitting resolution of minute frequency differences and precise determination of long-range J-couplings. The measurement of J-couplings with the high precision offered by zero-field NMR may allow further refinements in the determination of molecular structure and conformation.

}, keywords = {density}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja312239v}, url = {://WOS:000315936700050}, author = {Blanchard, J. W. and Ledbetter, M. P. and Theis, T. and Butler, M. C. and Budker, D. and Pines, A.} } @article {243, title = {HyperCEST detection of a 129Xe-based contrast agent composed of cryptophane-A molecular cages on a bacteriophage scaffold}, journal = {Magnetic Resonance in Medicine}, volume = {69}, year = {2013}, pages = {1245-1252}, author = {Stevens, T.K. and Palaniappan, K.K. and Ramirez, R.M. and Francis, M.B. and Wemmer, D.E. and Pines, A.} } @article {1350, title = {Hyperpolarized xenon-based molecular sensors for label-free detection of analytes}, journal = {Journal of the American Chemical Society}, volume = {136}, year = {2013}, month = {12/2013}, pages = {164-168}, doi = {10.1021/ja406760r}, author = {Garimella, Praveena and Meldrum, Tyler and Witus, Leah Suzanne and Smith, Monica and Bajaj, Vikram and Wemmer, David E. and Francis, Matthew B. and Pines, Alexander} } @article {244, title = {Molecular imaging of cancer cells using a bacteriophage-based (129) xe NMR biosensor.}, journal = {Angewandte Chemie-International Edition}, volume = {52}, year = {2013}, pages = {4849-4853}, edition = {2013 Mar 28}, doi = {10.1002/anie.201300170}, author = {Palaniappan, K. K. and Ramirez, R.M. and Bajaj, V.S. and Wemmer, D.E. and Pines, A. and Francis, M.B.} } @article {246, title = {Multiplets at zero magnetic field: The geometry of zero-field NMR}, journal = {The Journal of Chemical Physics}, volume = {138}, year = {2013}, month = {05/14/}, pages = {184202-15}, keywords = {Zeeman effect}, url = {http://dx.doi.org/10.1063/1.4803144}, author = {Butler, Mark C. and Ledbetter, Micah P. and Theis, Thomas and Blanchard, John W. and Budker, Dmitry and Pines, Alexander} } @article {1095, title = {Nanoemulsion contrast agents with sub-picomolar sensitivity for xenon NMR}, journal = {Journal of the American Chemical Society}, year = {2013}, month = {06/2013}, doi = {10.1021/ja402885q}, author = {Stevens, T. K. and Ramirez, R. M. and Pines, A.} } @article {1094, title = {Parahydrogen-induced polarization at zero magnetic field}, journal = {The Journal of Chemical Physics}, volume = {138}, year = {2013}, month = {06/2013}, pages = {234201}, abstract = {

We use symmetry arguments and simple model systems to describe the conversion of the singlet state of parahydrogen into an oscillating sample magnetization at zero magnetic field. During an initial period of free evolution governed by the scalar-coupling Hamiltonian HJ, the singlet state is converted into scalar spin order involving spins throughout the molecule. A short dc pulse along the z axis rotates the transverse spin components of nuclear species I and S through different angles, converting a portion of the scalar order into vector order. The development of vector order can be described analytically by means of single-transition operators, and it is found to be maximal when the transverse components of I are rotated by an angle of \±π/2 relative to those of S. A period of free evolution follows the pulse, during which the vector order evolves as a set of oscillating coherences. The imaginary parts of the coherences represent spin order that is not directly detectable, while the real parts can be identified with oscillations in the z component of the molecular spin dipole. The dipole oscillations are due to a periodic exchange between Iz and Sz, which have different gyromagnetic ratios. The frequency components of the resulting spectrum are imaginary, since the pulse cannot directly induce magnetization in the sample; it is only during the evolution under HJ that the vector order present at the end of the pulse evolves into detectable magnetization. \© 2013 AIP Publishing LLC. [http://dx.doi.org/10.1063/1.4805062]

}, doi = {doi: http://dx.doi.org/10.1063/1.4805062}, url = {http://link.aip.org/link/?JCP/138/234201\&aemail=author}, author = {Butler, Mark C. and Kervern, Gwendal and Theis, Thomas and Ledbetter, Micah P. and Ganssle, Paul J. and Blanchard, John W. and Budker, Dmitry and Pines, Alexander} } @article {1074, title = {Sensitive magnetic control of ensemble nuclear spin hyperpolarization in diamond}, journal = {Nature Communications}, volume = {4}, year = {2013}, note = {Nature communicationsWang, Hai-JingShin, Chang SAvalos, Claudia ESeltzer, Scott JBudker, DmitryPines, AlexanderBajaj, Vikram SengEngland2013/06/06 06:00Nat Commun. 2013 Jun 5;4:1940. doi: 10.1038/ncomms2930.}, month = {June 5, 2013}, pages = {1940}, chapter = {1940}, abstract = {

Dynamic nuclear polarization, which transfers the spin polarization of electrons to nuclei, is routinely applied to enhance the sensitivity of nuclear magnetic resonance. This method is particularly useful when spin hyperpolarization can be produced and controlled optically or electrically. Here we show complete polarization of nuclei located near optically polarized nitrogen-vacancy centres in diamond. Close to the ground-state level anti-crossing condition of the nitrogen-vacancy electron spins, (13)C nuclei in the first shell are polarized in a pattern that depends sensitively upon the magnetic field. Based on the anisotropy of the hyperfine coupling and of the optical polarization mechanism, we predict and observe a reversal of the nuclear spin polarization with only a few millitesla change in the magnetic field. This method of magnetic control of high nuclear polarization at room temperature can be applied in sensitivity enhanced nuclear magnetic resonance of bulk nuclei, nuclear-based spintronics, and quantum computation in diamond.

}, isbn = {2041-1723 (Linking)}, doi = {10.1038/ncomms2930}, url = {http://www.ncbi.nlm.nih.gov/pubmed/23736952}, author = {Wang, H. J. and Shin, C. S. and Avalos, C. E. and Seltzer, S. J. and Budker, D. and Pines, A. and Bajaj, V. S.} } @article {1318, title = {Suppression of electron spin decoherence of the diamond NV center by a transverse magnetic field}, journal = {Physical Review B}, volume = {88}, year = {2013}, month = {10/2013}, abstract = {

We demonstrate that the spin decoherence of nitrogen vacancy (NV) centers in diamond can be suppressed by a transverse magnetic field if the electron spin bath is the primary decoherence source. The NV spin coherence, created in \“a decoherence-free subspace,\” is protected by the transverse component of the zero-field splitting, increasing the spin-coherence time about twofold. The decoherence due to the electron spin bath is also suppressed at magnetic fields stronger than \∼25 G when applied parallel to the NV symmetry axis. Our method can be used to extend the spin-coherence time of similar spin systems for applications in quantum computing, field sensing, and other metrologies.

}, doi = {10.1103/PhysRevB.88.161412}, url = {http://prb.aps.org/abstract/PRB/v88/i16/e161412}, author = {Shin, Chang S. and Avalos, Claudia E. and Butler, Mark C. and Wang, Hai-Jing and Seltzer, Scott J. and Liu, Ren-Bao and Pines, Alexander and Bajaj, Vikram S.} } @article {251, title = {Liquid-State Nuclear Spin Comagnetometers}, journal = {Physical Review Letters}, volume = {108}, year = {2012}, note = {Phys Rev Lett973FATimes Cited:0Cited References Count:36}, month = {Jun 15}, abstract = {

We discuss nuclear spin comagnetometers based on ultralow-field nuclear magnetic resonance in mixtures of miscible solvents, each rich in a different nuclear spin. In one version thereof, Larmor precession of protons and F-19 nuclei in a mixture of thermally polarized pentane and hexafluorobenzene is monitored via a sensitive alkali-vapor magnetometer. We realize transverse relaxation times in excess of 20 s and suppression of magnetic field fluctuations by a factor of 3400. We estimate it should be possible to achieve single-shot sensitivity of about 5 x 10(-9) Hz, or about 5 x 10(-11) Hz in approximate to 1 day of integration. In a second version, spin precession of protons and Xe-129 nuclei in a mixture of pentane and hyperpolarized liquid xenon is monitored using superconducting quantum interference devices. Application to spin-gravity experiments, electric dipole moment experiments, and sensitive gyroscopes is discussed.

}, keywords = {nmr}, isbn = {0031-9007}, doi = {Doi 10.1103/Physrevlett.108.243001}, url = {://WOS:000306342000010}, author = {Ledbetter, M. P. and Pustelny, S. and Budker, D. and Romalis, M. V. and Blanchard, J. W. and Pines, A.} } @article {250, title = {Measurement of Arterial Input Function in Hyperpolarized C-13 Studies}, journal = {Applied Magnetic Resonance}, volume = {43}, year = {2012}, note = {Appl Magn Reson974GTTimes Cited:0Cited References Count:16}, month = {Jul}, pages = {289-297}, abstract = {

Recently, hyperpolarized substrates generated through dynamic nuclear polarization have been introduced to study in vivo metabolism. Injection of hyperpolarized [1-C-13] pyruvate, the most widely used substrate, allows detection of time courses of [1-C-13] pyruvate and its metabolic products, such as [1-C-13] lactate and C-13-bicarbonate, in various organs. However, quantitative metabolic modeling of in vivo data to measure specific metabolic rates remains challenging without measuring the input function. In this study, we demonstrate that the input function of [1-C-13] pyruvate can be measured in vivo in the rat carotid artery using an implantable coil.

}, keywords = {kinetics}, isbn = {0937-9347}, doi = {Doi 10.1007/S00723-012-0348-3}, url = {://WOS:000306421200024}, author = {Marjanska, M. and Teisseyre, T. Z. and Halpern-Manners, N. W. and Zhang, Y. and Iltis, I. and Bajaj, V. and Ugurbil, K. and Pines, A. and Henry, P. G.} } @article {249, title = {Room-temperature operation of a radiofrequency diamond magnetometer near the shot-noise limit}, journal = {Journal of Applied Physics}, volume = {112}, year = {2012}, note = {J Appl Phys061ECTimes Cited:1Cited References Count:15}, month = {Dec 15, 2012}, pages = {124519}, chapter = {124519}, abstract = {

We operate a nitrogen-vacancy (NV-) diamond magnetometer at ambient temperatures and study the dependence of its bandwidth on experimental parameters including optical and microwave excitation powers. A model based on the Bloch equations is used to analyze the NV center\&$\#$39;s response time, tau, during continuous optical and microwave irradiation, and tau(-1) is shown to be a weighted average of T-1(-1) and T-2(-1), where T-1 and T-2 are the longitudinal and transverse relaxation times of the electron spin during optical irradiation. We measured a maximum detection bandwidth of similar to 1.6 MHz with optical excitation intensity of similar to 2.3MW/cm(2), limited by the available optical power. The sensitivity of the NV ensemble for continuous-wave magnetometry in the presence of photon shot noise is analyzed. Two detection schemes are compared, one involving modulation of the fluorescence by an oscillating magnetic field while the microwave frequency is held constant, and the other involving double modulation of the fluorescence when the microwave frequency is modulated during the detection. For the first of these methods, we measure a sensitivity of 4.6 +/- 0.3 nT/root Hz, unprecedented in a detector with this active volume of similar to 10 mu m(3) and close to the photon-shot-noise limit of our experiment. The measured bandwidth and sensitivity of our device should allow detection of micro-scale NMR signals with microfluidic devices. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4771924]

}, keywords = {spin}, isbn = {0021-8979}, doi = {Doi 10.1063/1.4771924}, url = {http://link.aip.org/link/doi/10.1063/1.4771924}, author = {Shin, C. S. and Avalos, C. E. and Butler, M. C. and Trease, D. R. and Seltzer, S. J. and Mustonen, J. P. and Kennedy, D. J. and Acosta, V. M. and Budker, D. and Pines, A. and Bajaj, V. S.} } @article {248, title = {Zero-Field NMR Enhanced by Parahydrogen in Reversible Exchange}, journal = {Journal of the American Chemical Society}, volume = {134}, year = {2012}, note = {J Am Chem Soc909GLTimes Cited:2Cited References Count:40}, month = {02/2012}, pages = {3987-3990}, abstract = {

We have recently demonstrated that sensitive and chemically specific NMR spectra can be recorded in the absence of a magnetic field using hydrogenative parahydrogen induced polarization (PHIP)(1-3) and detection with an optical atomic magnetometer. Here, we show that non-hydrogenative para-hydrogen-induced polarization(4-6) (NH-PHIP) can also dramatically enhance the sensitivity of zero-field NMR. We demonstrate the detection of pyridine, at concentrations as low as 6 mM in a sample volume of 250 mu L, with sufficient sensitivity to resolve all identifying spectral features, as supported by numerical simulations. Because the NH-PHIP mechanism is nonreactive, operates in situ, and eliminates the need for a prepolarizing magnet, its combination with optical atomic magnetometry will greatly broaden the analytical capabilities of zero-field and low-field NMR.

}, keywords = {gas}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja2112405}, url = {://WOS:000301550800015}, author = {Theis, T. and Ledbetter, M. P. and Kervern, G. and Blanchard, J. W. and Ganssle, P. J. and Butler, M. C. and Shin, H. D. and Budker, D. and Pines, A.} } @article {257, title = {Band-selective chemical exchange saturation transfer imaging with hyperpolarized xenon-based molecular sensors}, journal = {Journal of Magnetic Resonance}, volume = {213}, year = {2011}, note = {J Magn Reson847UKTimes Cited:3Cited References Count:29}, month = {Dec}, pages = {14-21}, abstract = {

Molecular imaging based on saturation transfer in exchanging systems is a tool for amplified and chemically specific magnetic resonance imaging. Xenon-based molecular sensors are a promising category of molecular imaging agents in which chemical exchange of dissolved xenon between its bulk and agent-bound phases has been use to achieve sub-picomolar detection sensitivity. Control over the saturation transfer dynamics, particularly when multiple exchanging resonances are present in the spectra, requires saturation fields of limited bandwidth and is generally accomplished by continuous wave irradiation. We demonstrate instead how band-selective saturation sequences based on multiple pulse inversion elements can yield saturation bandwidth tuneable over a wide range, while depositing less RF power in the sample. We show how these sequences can be used in imaging experiments that require spatial-spectral and multispectral saturation. The results should be applicable to all CEST experiments and, in particular, will provide the spectroscopic control required for applications of arrays of xenon chemical sensors in microfluidic chemical analysis devices. (C) 2011 Elsevier Inc. All rights reserved.

}, keywords = {xe-129}, isbn = {1090-7807}, doi = {Doi 10.1016/J.Jmr.2011.06.027}, url = {://WOS:000296997800002}, author = {Meldrum, T. and Bajaj, V. S. and Wemmer, D. E. and Pines, A.} } @article {255, title = {Comrehensive sampling with prior information in remotely detected MRI of microfluidic devices}, journal = {Journal of Magnetic Resonance}, year = {2011}, pages = {13-20}, author = {Teisseyre, T. and Paulsen, J.L. and Bajaj, V.S. and Halpern-Manners, N. and Pines, A.} } @article {258, title = {Near-Zero-Field Nuclear Magnetic Resonance}, journal = {Physical Review Letters}, volume = {107}, year = {2011}, note = {Phys Rev Lett813YOTimes Cited:5Cited References Count:26}, month = {Sep 1}, abstract = {

We investigate nuclear magnetic resonance (NMR) in near zero field, where the Zeeman interaction can be treated as a perturbation to the electron mediated scalar interaction (J coupling). This is in stark contrast to the high-field case, where heteronuclear J couplings are normally treated as a small perturbation. We show that the presence of very small magnetic fields results in splitting of the zero-field NMR lines, imparting considerable additional information to the pure zero-field spectra. Experimental results are in good agreement with first-order perturbation theory and with full numerical simulation when perturbation theory breaks down. We present simple rules for understanding the splitting patterns in near-zero-field NMR, which can be applied to molecules with nontrivial spectra.

}, keywords = {mri}, isbn = {0031-9007}, doi = {Doi 10.1103/Physrevlett.107.107601}, url = {://WOS:000294406600017}, author = {Ledbetter, M. P. and Theis, T. and Blanchard, J. W. and Ring, H. and Ganssle, P. and Appelt, S. and Blumich, B. and Pines, A. and Budker, D.} } @article {253, title = {Parahydrogen-enhanced zero-field nuclear magnetic resonance}, journal = {Nature Physics}, volume = {7}, year = {2011}, note = {Nat Phys786FYTimes Cited:9Cited References Count:31}, month = {Jul}, pages = {571-575}, abstract = {

Nuclear magnetic resonance, conventionally detected in magnetic fields of several tesla, is a powerful analytical tool for the determination of molecular identity, structure and function. With the advent of prepolarization methods and detection schemes using atomic magnetometers or superconducting quantum interference devices, interest in NMR in fields comparable to the Earth\&$\#$39;s magnetic field and below (down to zero field) has been revived. Despite the use of superconducting quantum interference devices or atomic magnetometers, low-field NMR typically suffers from low sensitivity compared with conventional high-field NMR. Here we demonstrate direct detection of zero-field NMR signals generated through parahydrogen-induced polarization, enabling high-resolution NMR without the use of any magnets. The sensitivity is sufficient to observe spectra exhibiting (13)C-(1)H scalar nuclear spin-spin couplings (known as J couplings) in compounds with (13)C in natural abundance, without the need for signal averaging. The resulting spectra show distinct features that aid chemical fingerprinting.

}, keywords = {order}, isbn = {1745-2473}, doi = {Doi 10.1038/Nphys1986}, url = {://WOS:000292290000017}, author = {Theis, T. and Ganssle, P. and Kervern, G. and Knappe, S. and Kitching, J. and Ledbetter, M. P. and Budker, D. and Pines, A.} } @article {256, title = {Relaxivity of Gadolinium Complexes Detected by Atomic Magnetometry}, journal = {Magnetic Resonance in Medicine}, volume = {66}, year = {2011}, note = {Magn Reson Med799AVTimes Cited:1Cited References Count:23}, month = {Aug}, pages = {605-608}, abstract = {

Laser atomic magnetomeby is a portable and low-cost yet highly sensitive method for low magnetic field detection. In this work, the atomic magnetometer was used in a remote-detection geometry to measure the relaxivity of aqueous gadolinium-diethylenetriamine pentaacetic acid Gd(DTPA) at the Earth\&$\#$39;s magnetic field (40 mu T). The measured relaxivity of 9.7 +/- 2.0 s(-1) mM(-1) is consistent with field-cycling experiments measured at slightly higher magnetic fields, but no cryogens or strong and homogeneous magnetic field were required for this experiment. The field-independent sensitivity of 80 fT Hz(-1/2) allowed an in vitro detection limit of similar to 10 mu M Gd(DTPA) to be measured in aqueous buffer solution. The low detection limit and enhanced relaxivity of Gd-containing complexes at Earth\&$\#$39;s field motivate continued development of atomic magnetometry toward medical applications. Magn Reson Med 66:605-608, 2011. (C) 2011 Wiley-Liss, Inc.

}, keywords = {nmr}, isbn = {0740-3194}, doi = {Doi 10.1002/Mrm.22811}, url = {://WOS:000293256800033}, author = {Michalak, D. J. and Xu, S. J. and Lowery, T. J. and Crawford, C. W. and Ledbetter, M. and Bouchard, L. S. and Wemmer, D. E. and Budker, D. and Pines, A.} } @article {259, title = {Remotely Detected MRI Velocimetry in Microporous Bead Packs}, journal = {Journal of Physical Chemistry A}, volume = {115}, year = {2011}, note = {J Phys Chem A752NBTimes Cited:1Cited References Count:52}, month = {Apr 28}, pages = {4023-4030}, abstract = {

Many NAIR and MRI methods probe fluid dynamics within macro- and mesoporous materials, but with few exceptions, they report on its macroscopically averaged properties. MRI methods are generally unable to localize microscopic features of flow within macroscopic samples because the fraction of the enclosing detector volume occupied by these features is so small. We have recently overcome this problem using remotely detected MRI velocimetry, a technique in which spatial, chemical, and velocity information about elements of the flow is encoded with a conventional NMR coil and detected sensitively at the sample outflow by a volume-matched microdetector. Here, we apply this method to microporous model systems, recording MRI images that correlate local velocity, spin relaxation, and time-of-flight in microscopic resolution and three spatial dimensions. Our results illustrate that remotely detected MRI is an effective approach to elucidate flow dynamics in porous materials including bead pack microreactors and chromatography columns.

}, keywords = {gradients}, isbn = {1089-5639}, doi = {Doi 10.1021/Jp109728j}, url = {://WOS:000289697500039}, author = {Halpern-Manners, N. W. and Paulsen, J. L. and Bajaj, V. S. and Pines, A.} } @article {254, title = {Remotely Detected NMR for the Characterization of Flow and Fast Chromatographic Separations Using Organic Polymer Monoliths}, journal = {Analytical Chemistry}, volume = {83}, year = {2011}, note = {Anal Chem798ZVTimes Cited:4Cited References Count:35}, month = {Aug 1}, pages = {6004-6010}, abstract = {

An application of remotely detected magnetic resonance imaging is demonstrated for the characterization of flow and the detection of fast, small molecule separations within hypercrosslinked polymer monoliths. The hyper-cross-linked monoliths exhibited excellent ruggedness, with a transit time relative standard deviation of less than 2.1\%, even after more than 300 column volumes were pumped through at high pressure and flow. Magnetic resonance imaging enabled high. resolution intensity and velocity-encoded images of mobile phase flow through the monolith. The images confirm that the presence of a polymer monolith within the capillary disrupts the parabolic laminar flow profile that is characteristic of mobile phase flow within an open tube. As a result, the mobile phase and analytes are equally distributed in the radial direction throughout the monolith. Also, in-line monitoring of chromatographic separations of small molecules at high flow rates is shown. The coupling of monolithic chromatography columns and NMR provides both real-time peak detection and chemical shift information for small aromatic molecules. These experiments demonstrate the unique power of magnetic resonance, both direct and remote, in studying chromatographic processes.

}, keywords = {visualization}, isbn = {0003-2700}, doi = {Doi 10.1021/Ac2010108}, url = {://WOS:000293252500029}, author = {Teisseyre, T. Z. and Urban, J. and Halpern-Manners, N. W. and Chambers, S. D. and Bajaj, V. S. and Svec, F. and Pines, A.} } @article {252, title = {Ultrafast optical encoding of magnetic resonance}, journal = {Chemical Physics Letters}, volume = {503}, year = {2011}, note = {Chem Phys Lett719FWTimes Cited:0Cited References Count:19}, month = {Feb 17}, pages = {187-190}, abstract = {

Temporal resolution in magnetic resonance imaging (MRI) is limited by the time required to encode the position of spins using time-varying (10-100 ms) magnetic field gradients. Here, we demonstrate spatial encoding of MRI images in a time that is three orders of magnitude shorter than what is possible by conventional gradient encoding techniques. Our method exploits the chemically induced dynamic nuclear polarization (CIDNP) effect and is an initial example of a set of approaches that seek to combine the favorable properties of optical spectroscopy with those of NMR for polarization, encoding, and detection. (C) 2010 Elsevier B.V. All rights reserved.

}, keywords = {state}, isbn = {0009-2614}, doi = {Doi 10.1016/J.Cplett.2010.12.063}, url = {://WOS:000287187800001}, author = {Trease, D. and Bajaj, V. S. and Paulsen, J. and Pines, A.} } @article {262, title = {Compressed sensing of remotely detected MRI velocimetry in microfluidics}, journal = {Journal of Magnetic Resonance}, volume = {205}, year = {2010}, month = {8//}, pages = {196-201}, keywords = {Flow imaging}, isbn = {1090-7807}, doi = {http://dx.doi.org/10.1016/j.jmr.2010.04.016}, url = {http://www.sciencedirect.com/science/article/pii/S1090780710001187}, author = {Paulsen, Jeffrey and Bajaj, Vikram S. and Pines, Alexander} } @article {260, title = {Investigation of antirelaxation coatings for alkali-metal vapor cells using surface science techniques}, journal = {Journal of Chemical Physics}, volume = {133}, year = {2010}, note = {J. Chem. Phys.ISI Document Delivery No.: 667NNTimes Cited: 6Cited Reference Count: 81Seltzer, S. J. Michalak, D. J. Donaldson, M. H. Balabas, M. V. Barber, S. K. Bernasek, S. L. Bouchiat, M. -A. Hexemer, A. Hibberd, A. M. Kimball, D. F. Jackson Jaye, C. Karaulanov, T. Narducci, F. A. Rangwala, S. A. Robinson, H. G. Shmakov, A. K. Voronov, D. L. Yashchuk, V. V. Pines, A. Budker, D.Office of Science, Office of Basic Energy Sciences, Materials Sciences Division and Nuclear Science Division, of the U. S. Department of Energy [DE-AC02-05CH11231]; NSF/DST [PHY-0425916]; Office of Naval Research (ONR) [N0001409WX21049]The authors thank Daniel Fischer, Kristin Schmidt, and Ed Kramer for assistance with the NEXAFS measurements, and Joel Ager, Joshua Wnuk, David Trease, and Gwendal Kervern for helpful discussions and other assistance. S.J.S., D.J.M., M. H. D., A. P., and D. B., the Advanced Light Source, and the DSC, FTIR, and AFM studies were supported by the Director, Office of Science, Office of Basic Energy Sciences, Materials Sciences Division and Nuclear Science Division, of the U. S. Department of Energy under Contract No. DE-AC02-05CH11231 at Lawrence Berkeley National Laboratory. Other parts of this work were funded by the NSF/DST under Grant No. PHY-0425916 for U.S.-India cooperative research, by an Office of Naval Research (ONR) MURI grant, and by ONR under Grant No. N0001409WX21049.AMER INST PHYSICSMELVILLE}, month = {October 11, 2010}, pages = {144703}, type = {Article}, chapter = {144703}, abstract = {

Many technologies based on cells containing alkali-metal atomic vapor benefit from the use of antirelaxation surface coatings in order to preserve atomic spin polarization. In particular, paraffin has been used for this purpose for several decades and has been demonstrated to allow an atom to experience up to 10 000 collisions with the walls of its container without depolarizing, but the details of its operation remain poorly understood. We apply modern surface and bulk techniques to the study of paraffin coatings in order to characterize the properties that enable the effective preservation of alkali spin polarization. These methods include Fourier transform infrared spectroscopy, differential scanning calorimetry, atomic force microscopy, near-edge x-ray absorption fine structure spectroscopy, and x-ray photoelectron spectroscopy. We also compare the light-induced atomic desorption yields of several different paraffin materials. Experimental results include the determination that crystallinity of the coating material is unnecessary, and the detection of CvC double bonds present within a particular class of effective paraffin coatings. Further study should lead to the development of more robust paraffin antirelaxation coatings, as well as the design and synthesis of new classes of coating materials. (C) 2010 American Institute of Physics. [doi:10.1063/1.3489922]

}, keywords = {SPECTROSCOPY}, isbn = {0021-9606}, doi = {10.1063/1.3489922}, url = {http://link.aip.org/link/doi/10.1063/1.3489922}, author = {Seltzer, S. J. and Michalak, D. J. and Donaldson, M. H. and Balabas, M. V. and Barber, S. K. and Bernasek, S. L. and Bouchiat, M. A. and Hexemer, A. and Hibberd, A. M. and Kimball, D. F. J. and Jaye, C. and Karaulanov, T. and Narducci, F. A. and Rangwala, S. A. and Robinson, H. G. and Shmakov, A. K. and Voronov, D. L. and Yashchuk, V. V. and Pines, A. and Budker, D.} } @article {265, title = {Magnetic resonance imaging of oscillating electrical currents}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {107}, year = {2010}, note = {P Natl Acad Sci USA595DPTimes Cited:1Cited References Count:47}, month = {May 11}, pages = {8519-8524}, abstract = {

Functional MRI has become an important tool of researchers and clinicians who seek to understand patterns of neuronal activation that accompany sensory and cognitive processes. However, the interpretation of fMRI images rests on assumptions about the relationship between neuronal firing and hemodynamic response that are not firmly grounded in rigorous theory or experimental evidence. Further, the blood-oxygen-level-dependent effect, which correlates an MRI observable to neuronal firing, evolves over a period that is 2 orders of magnitude longer than the underlying processes that are thought to cause it. Here, we instead demonstrate experiments to directly image oscillating currents by MRI. The approach rests on a resonant interaction between an applied rf field and an oscillating magnetic field in the sample and, as such, permits quantitative, frequency-selective measurements of current density without spatial or temporal cancellation. We apply this method in a current loop phantom, mapping its magnetic field and achieving a detection sensitivity near the threshold required for the detection of neuronal currents. Because the contrast mechanism is under spectroscopic control, we are able to demonstrate how ramped and phase-modulated spin-lock radiation can enhance the sensitivity and robustness of the experiment. We further demonstrate the combination of these methods with remote detection, a technique in which the encoding and detection of an MRI experiment are separated by sample flow or translation. We illustrate that remotely detected MRI permits the measurement of currents in small volumes of flowing water with high sensitivity and spatial resolution.

}, keywords = {nerve}, isbn = {0027-8424}, doi = {Doi 10.1073/Pnas.1003146107}, url = {://WOS:000277591200008}, author = {Halpern-Manners, N. W. and Bajaj, V. S. and Teisseyre, T. Z. and Pines, A.} } @article {261, title = {MRI Thermometry Based on Encapsulated Hyperpolarized Xenon}, journal = {Chemphyschem}, volume = {11}, year = {2010}, note = {Chemphyschem691LFTimes Cited:2Cited References Count:25}, month = {Nov 15}, pages = {3529-3533}, abstract = {

A new approach to MRI thermometry using encapsulated hyperpolarized xenon is demonstrated The method is based on the temperature dependent chemical shift of hyperpolarized xenon in a cryptophane-A cage This shift is linear with a slope of 029 ppm degrees C(-1) which is perceptibly higher than the shift of the proton resonance frequency of water (ca 0 01 ppm degrees C(-1)) that is currently used for MRI thermometry Using spectroscopic imaging techniques, we collected temperature maps of a phantom sample that could discriminate by direct NMR detection between temperature differences of 0 1 degrees C at a sensor concentration of 150 mu M Alternatively, the xenon-in-cage chemical shift was determined by indirect detection using saturation transfer techniques (Hyper-CEST) that allow detection of nanomolar agent concentrations Thermometry based on hyperpolarized xenon sensors improves the accuracy of currently available MRI thermometry methods, potentially giving rise to biomedical applications of biosensors functionalized for binding to specific target molecules

}, keywords = {xe-129}, isbn = {1439-4235}, doi = {Doi 10.1002/Cphc.201000507}, url = {://WOS:000285080600023}, author = {Schilling, F. and Schroder, L. and Palaniappan, K. K. and Zapf, S. and Wemmer, D. E. and Pines, A.} } @article {263, title = {A Xenon-Based Molecular Sensor Assembled on an MS2 Viral Capsid Scaffold}, journal = {Journal of the American Chemical Society}, volume = {132}, year = {2010}, note = {J Am Chem Soc589OATimes Cited:20Cited References Count:23}, month = {May 5}, pages = {5936-+}, abstract = {

In MRI, anatomical structures are most often differentiated by variations in their bulk magnetic properties. Alternatively, exogenous contrast agents can be attached to chemical moieties that confer affinity to molecular targets; the distribution of such contrast agents can be imaged by magnetic resonance. Xenon-based molecular sensors are molecular imaging agents that rely on the reversible exchange of hyperpolarized xenon between the bulk and a specifically targeted host-guest complex. We have incorporated similar to 125 xenon sensor molecules in the interior of an MS2 viral capsid, conferring multivalency and other properties of the viral capsid to the sensor molecule. The resulting signal amplification facilitates the detection of sensor at 0.7 pM, the lowest to date for any molecular imaging agent used in magnetic resonance. This amplification promises the detection of chemical targets at much lower concentrations than would be possible without the capsid scaffold.

}, keywords = {nmr}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja100319f}, url = {://WOS:000277158500007}, author = {Meldrum, T. and Seim, K. L. and Bajaj, V. S. and Palaniappan, K. K. and Wu, W. and Francis, M. B. and Wemmer, D. E. and Pines, A.} } @article {264, title = {Xenon-based molecular sensors in lipid suspensions}, journal = {Journal of Magnetic Resonance}, volume = {205}, year = {2010}, note = {J Magn Reson627SZTimes Cited:8Cited References Count:23}, month = {Aug}, pages = {242-246}, abstract = {

There have been many proposals to use xenon-based molecular sensors in biological settings. Fundamental to understanding the properties of these sensors in vivo is characterizing their behavior in lipid environments. We report the investigation of xenon-based molecular sensors in suspensions of lipid vesicles with a size comparable to cells. We detail spectroscopic properties of sensors associated with lipid vesicles as well as those in equilibrium in the surrounding solution. We characterize the dependence of the spectral parameters on temperature, relevant for studies at physiological temperatures. We also demonstrate the ability to perform selective saturation transfer (Hyper-CEST) between sensor, both lipid bound and unbound, and the bulk solution. Lastly, we demonstrate the applicability of saturation transfer in the heterogeneous medium as an imaging modality. (C) 2010 Elsevier Inc. All rights reserved.

}, keywords = {binding}, isbn = {1090-7807}, doi = {Doi 10.1016/J.Jmr.2010.05.005}, url = {://WOS:000280064500008}, author = {Meldrum, T. and Schroder, L. and Denger, P. and Wemmer, D. E. and Pines, A.} } @article {266, title = {Zooming In on Microscopic Flow by Remotely Detected MRI}, journal = {Science}, volume = {330}, year = {2010}, note = {Science682BUTimes Cited:12Cited References Count:27}, month = {Nov 19}, pages = {1078-1081}, abstract = {

Magnetic resonance imaging (MRI) can elucidate the interior structure of an optically opaque object in unparalleled detail but is ultimately limited by the need to enclose the object within a detection coil; acquiring the image with increasingly smaller pixels reduces the sensitivity, because each pixel occupies a proportionately smaller fraction of the detector\&$\#$39;s volume. We developed a technique that overcomes this limitation by means of remotely detected MRI. Images of fluids flowing in channel assemblies are encoded into the phase and intensity of the constituent molecules\&$\#$39; nuclear magnetic resonance signals and then decoded by a volume-matched detector after the fluids flow out of the sample. In combination with compressive sampling, we thus obtain microscopic images of flow and velocity distributions similar to 10(6) times faster than is possible with conventional MRI on this hardware. Our results illustrate the facile integration of MRI with microfluidic assays and suggest generalizations to other systems involving microscopic flow.

}, keywords = {biosensor}, isbn = {0036-8075}, doi = {Doi 10.1126/Science.1192313}, url = {://WOS:000284374700036}, author = {Bajaj, V. S. and Paulsen, J. and Harel, E. and Pines, A.} } @article {269, title = {Distortion-free magnetic resonance imaging in the zero-field limit}, journal = {Journal of Magnetic Resonance}, volume = {200}, year = {2009}, note = {J Magn Reson526AWTimes Cited:6Cited References Count:29}, month = {Oct}, pages = {285-290}, abstract = {

MRI is a powerful technique for clinical diagnosis and materials characterization. Images are acquired in a homogeneous static magnetic field much higher than the fields generated across the field of view by the spatially encoding field gradients. Without such a high field, the concomitant components of the field gradient dictated by Maxwell\&$\#$39;s equations lead to severe distortions that make imaging impossible with conventional MRI encoding. In this paper, we present a distortion-free image of a phantom acquired with a fundamentally different methodology in which the applied static field approaches zero. Our technique involves encoding with pulses of uniform and gradient field, and acquiring the magnetic field signals with a SQUID. The method can be extended to weak ambient fields, potentially enabling imaging in the Earth\&$\#$39;s field without cancellation coils or shielding. Other potential applications include quantum information processing and fundamental studies of long-range ferromagnetic interactions. (C) 2009 Elsevier Inc. All rights reserved.

}, keywords = {gradients}, isbn = {1090-7807}, doi = {Doi 10.1016/J.Jmr.2009.07.016}, url = {://WOS:000272260900015}, author = {Kelso, N. and Lee, S. K. and Bouchard, L. S. and Demas, V. and M{\"u}ck, M. and Pines, A. and Clarke, J.} } @article {271, title = {{\textquoteright}Ex situ{\textquoteright} magnetic resonance volume imaging}, journal = {Chemical Physics Letters}, volume = {467}, year = {2009}, note = {Chem Phys Lett386VCTimes Cited:2Cited References Count:25}, month = {Jan 5}, pages = {398-401}, abstract = {

The portable NMR community has introduced advances that have allowed for a variety of studies. Imaging of static and moving objects has almost become standardized. The inherent static field gradients of portable systems have, however, limited such studies to imaging of slices perpendicular to the main gradient; full volume imaging in transportable, open systems has not been actively pursued. We present a true three-dimensional image of a phantom in an ex situ, electromagnet-based system. The basic concepts and designs put forth here extend in a straightforward fashion to higher fields and imaging of larger samples by ex situ methodologies. (C) 2008 Elsevier B.V. All rights reserved.

}, keywords = {array}, isbn = {0009-2614}, doi = {Doi 10.1016/J.Cplett.2008.11.069}, url = {://WOS:000261909700037}, author = {Demas, V. and Franck, J. M. and Bouchard, L. S. and Sakellariou, D. and Meriles, C. A. and Martin, R. and Prado, P. J. and Bussandri, A. and Reimer, J. A. and Pines, A.} } @article {267, title = {Hyperpolarized xenon NMR and MRI signal amplification by gas extraction}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {106}, year = {2009}, note = {P Natl Acad Sci USA503MDTimes Cited:12Cited References Count:33}, month = {Oct 6}, pages = {16903-16906}, abstract = {

A method is reported for enhancing the sensitivity of NMR of dissolved xenon by detecting the signal after extraction to the gas phase. We demonstrate hyperpolarized xenon signal amplification by gas extraction (Hyper-SAGE) in both NMR spectra and magnetic resonance images with time-of-flight information. Hyper-SAGE takes advantage of a change in physical phase to increase the density of polarized gas in the detection coil. At equilibrium, the concentration of gas-phase xenon is approximate to 10 times higher than that of the dissolved-phase gas. After extraction the xenon density can be further increased by several orders of magnitude by compression and/or liquefaction. Additionally, being a remote detection technique, the Hyper-SAGE effect is further enhanced in situations where the sample of interest would occupy only a small proportion of the traditional NMR receiver. Coupled with targeted xenon biosensors, Hyper-SAGE offers another path to highly sensitive molecular imaging of specific cell markers by detection of exhaled xenon gas.

}, keywords = {field}, isbn = {0027-8424}, doi = {Doi 10.1073/Pnas.0909147106}, url = {://WOS:000270537500005}, author = {Zhou, X. and Graziani, D. and Pines, A.} } @article {268, title = {Optical detection of NMR J-spectra at zero magnetic field}, journal = {Journal of Magnetic Resonance}, volume = {199}, year = {2009}, note = {J Magn Reson456YJTimes Cited:19Cited References Count:26}, month = {Jul}, pages = {25-29}, abstract = {

Scalar couplings of the form JI(1) . I(2) between nuclei impart valuable information about molecular structure to nuclear magnetic-resonance spectra. Here we demonstrate direct detection of J-spectra due to both heteronuclear and homonuclear J-coupling in a zero-field environment where the Zeeman interaction is completely absent. We show that characteristic functional groups exhibit distinct spectra with straightforward interpretation for chemical identification. Detection is performed with a microfabricated optical atomic magnetometer, providing high sensitivity to samples of microliter volumes. We obtain 0.1 Hz linewidths and measure scalar-coupling parameters with 4-mHz statistical uncertainty. We anticipate that the technique described here will provide a new modality for high-precision\" J spectroscopy\" using small samples oil microchip devices for multiplexed Screening, assaying, and sample identification in chemistry and biomedicine. (C) 2009 Elsevier Inc. All rights reserved.

}, keywords = {cells}, isbn = {1090-7807}, doi = {Doi 10.1016/J.Jmr.2009.03.008}, url = {://WOS:000266890300004}, author = {Ledbetter, M. P. and Crawford, C. W. and Pines, A. and Wemmer, D. E. and Knappe, S. and Kitching, J. and Budker, D.} } @article {272, title = {Picomolar sensitivity MRI and photoacoustic imaging of cobalt nanoparticles}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {106}, year = {2009}, note = {P Natl Acad Sci USA420HDTimes Cited:43Cited References Count:41}, month = {Mar 17}, pages = {4085-4089}, abstract = {

Multimodality imaging based on complementary detection principles has broad clinical applications and promises to improve the accuracy of medical diagnosis. This means that a tracer particle advantageously incorporates multiple functionalities into a single delivery vehicle. In the present work, we explore a unique combination of MRI and photoacoustic tomography (PAT) to detect picomolar concentrations of nanoparticles. The nanoconstruct consists of ferromagnetic (Co) particles coated with gold (Au) for biocompatibility and a unique shape that enables optical absorption over a broad range of frequencies. The end result is a dual-modality probe useful for the detection of trace amounts of nanoparticles in biological tissues, in which MRI provides volume detection, whereas PAT performs edge detection.

}, keywords = {cancer}, isbn = {0027-8424}, doi = {Doi 10.1073/Pnas.0813019106}, url = {://WOS:000264278800008}, author = {Bouchard, L. S. and Anwar, M. S. and Liu, G. L. and Hann, B. and Xie, Z. H. and Gray, J. W. and Wang, X. D. and Pines, A. and Chen, F. F.} } @article {270, title = {Shimmed matching pulses: Simultaneous control of rf and static gradients for inhomogeneity correction}, journal = {Journal of Chemical Physics}, volume = {131}, year = {2009}, note = {J Chem Phys536HUTimes Cited:4Cited References Count:30}, month = {Dec 21}, abstract = {

Portable NMR systems generally suffer from poor field homogeneity and are therefore used more commonly for imaging and relaxation measurements rather than for spectroscopy. In recent years, various approaches have been proposed to increase the sample volume that is usable for spectroscopy. These include approaches based on manual shimming and those based on clever combinations of modulated radio frequency and gradient fields. However, this volume remains small and, therefore, of limited utility. We present improved pulses designed to correct for inhomogeneous dispersion across wide ranges of frequency offsets without eliminating chemical shift or spatial encoding. This method, based on the adiabatic double passage, combines the relatively larger corrections available from spatially matched rf gradients [C. Meriles , J. Magn. Reson. 164, 177 (2003)]. with the adjustable corrections available from time-modulated static field gradients [D. Topgaard , Proc. Natl. Acad. Sci. U.S.A. 101, 17576 (2004)]. We explain the origins of these corrections with a theoretical model that simplifies and expedites the design of the pulse waveforms. We also present a generalized method for evaluating and comparing pulses designed for inhomogeneity correction. Experiments validate this method and support simulations that offer new possibilities for significantly enhanced performance in portable environments.

}, keywords = {design}, isbn = {0021-9606}, doi = {Doi 10.1063/1.3243850}, url = {://WOS:000273036300030}, author = {Franck, J. M. and Demas, V. and Martin, R. W. and Bouchard, L. S. and Pines, A.} } @article {273, title = {Flow in Porous Metallic Materials: A Magnetic Resonance Imaging Study}, journal = {Journal of Magnetic Resonance Imaging}, volume = {28}, year = {2008}, note = {J Magn Reson Imaging367QCTimes Cited:5Cited References Count:22}, month = {Nov}, pages = {1299-1302}, abstract = {

Purpose: To visualize flow dynamics of analytes inside porous metallic materials with laser-detected magnetic resonance imaging (MRI).Materials and Methods: We examine the flow of nuclear-polarized water in a porous stainless steel cylinder. Laser-detected MRI utilizes a sensitive optical atomic magnetometer as the detector. Imaging was performed in a remote-detection mode: the encoding was conducted in the Earth\&$\#$39;s magnetic field, and detection is conducted downstream of the encoding location. Conventional MRI (7T) was also performed for comparison.Results: Laser-detected MRI clearly showed MR images of water flowing through the sample, whereas conventional MRI provided no image.Conclusion: We demonstrated the viability of laser-detected MRI at low-field for studying porous metallic materials, extending MRI techniques to a new group of systems that is normally not accessible to conventional MRI.

}, keywords = {mri}, isbn = {1053-1807}, doi = {Doi 10.1002/Jmri.21532}, url = {://WOS:000260566100033}, author = {Xu, S. J. and Harel, E. and Michalak, D. J. and Crawford, C. W. and Budker, D. and Pines, A.} } @article {281, title = {Fluid-flow characterization with nuclear spins without magnetic resonance}, journal = {Applied Physics Letters}, volume = {93}, year = {2008}, note = {Appl Phys Lett345DHTimes Cited:2Cited References Count:20}, month = {Sep 1}, abstract = {

A technique for noninvasive monitoring of flow inside metallic enclosures using laser-based atomic magnetometry is introduced. The analyte is labeled via nuclear magnetization by magnets, thereby combining the polarization and encoding steps. No radiofrequency or audiofrequency pulses are involved. We demonstrate detection of flow inside an aluminum pipe with an inner diameter of 4.9 mm that has a constriction with a diameter of 1.6 mm and a length of 6.4 mm. The results agree with a model of spin density and relaxation indicating that our technique allows for fast, quantitative, and noninvasive diagnostics of flow with potential applications discussed below. (c) 2008 American Institute of Physics.

}, keywords = {mri}, isbn = {0003-6951}, doi = {Doi 10.1063/1.2977773}, url = {://WOS:000258975800042}, author = {Crawford, C. W. and Xu, S. J. and Siegel, E. J. and Budker, D. and Pines, A.} } @article {282, title = {NMR imaging of catalytic hydrogenation in microreactors with the use of para-hydrogen}, journal = {Science}, volume = {319}, year = {2008}, note = {Science254HBTimes Cited:55Cited References Count:33}, month = {Jan 25}, pages = {442-445}, abstract = {

Catalysis is vital to industrial chemistry, and the optimization of catalytic reactors attracts considerable resources. It has proven challenging to correlate the active regions in heterogeneous catalyst beds with morphology and to monitor multistep reactions within the bed. We demonstrate techniques, using magnetic resonance imaging and para- hydrogen ( p-H(2)) polarization, that allow direct visualization of gas- phase flow and the density of active catalyst in a packed- bed microreactor, as well as control over the dynamics of the polarized state in space and time to facilitate the study of subsequent reactions. These procedures are suitable for characterizing reactors and reactions in microfluidic devices where low sensitivity of conventional magnetic resonance would otherwise be the limiting factor.

}, keywords = {chip}, isbn = {0036-8075}, doi = {Doi 10.1126/Science.1151787}, url = {://WOS:000252576600031}, author = {Bouchard, L. S. and Burt, S. R. and Anwar, M. S. and Kovtunov, K. V. and Koptyug, I. V. and Pines, A.} } @article {275, title = {Remote detection of nuclear magnetic resonance with an anisotropic magnetoresistive sensor}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {105}, year = {2008}, note = {P Natl Acad Sci USA266XBTimes Cited:8Cited References Count:17}, month = {Feb 19}, pages = {2271-2273}, abstract = {

We report the detection of nuclear magnetic resonance (NMR) using an anisotropic magnetoresistive (AMR) sensor. A \"remote-detection\" arrangement was used in which protons in flowing water were prepolarized in the field of a superconducting NMR magnet, adiabatically inverted, and subsequently detected with an AMR sensor situated downstream from the magnet and the adiabatic inverter. AMR sensing is well suited for NMR detection in microfluidic \"lab-on-a-chip\" applications because the sensors are small, typically on the order of 10 mu m. An estimate of the sensitivity for an optimized system indicates that approximate to 6 x 10(13) protons in a volume of 1,000 mu m(3), prepolarized in a 10-kG magnetic field, can be detected with a signal-to-noise ratio of 3 in a 1-Hz bandwidth. This level of sensitivity is competitive with that demonstrated by microcoils in superconducting magnets and with the projected sensitivity of microfabricated atomic magnetometers.

}, keywords = {mri}, isbn = {0027-8424}, doi = {Doi 10.1073/Pnas.0712129105}, url = {://WOS:000253469900006}, author = {Verpillat, F. and Ledbetter, M. P. and Xu, S. and Michalak, D. J. and Hilty, C. and Bouchard, L. S. and Antonijevic, S. and Budker, D. and Pines, A.} } @article {280, title = {Spectrally resolved flow imaging of fluids inside a microfluidic chip with ultrahigh time resolution}, journal = {Journal of Magnetic Resonance}, volume = {193}, year = {2008}, note = {J Magn Reson336INTimes Cited:14Cited References Count:19}, month = {Aug}, pages = {199-206}, abstract = {

Microfluidics has advanced to become a complete lab-on-a-chip platform with applications across Many disciplines of scientific research. While optical techniques are primarily used as modes of detection, magnetic resonance (MR) is emerging as a potentially powerful and complementary tool because of its non-invasive operation and analytical fidelity. Two prevailing limitations Currently inhibit MR techniques on microfluidic devices: poor sensitivity and the relatively slow time scale of dynamics that can be probed. it is commonly assumed that the time scale of observation of one variable limits the certainty with which one can measure the complementary variable. For example, short observation times imply poor spectral resolution. In this article, we demonstrate a new methodology that overcomes this fundamental limit, allowing in principle for arbitrarily high temporal resolution with a sensitivity across the entire microfluidic device several Orders of magnitude greater than is possible by direct MR measurement. The enhancement is evidenced by recording chemically resolved fluid mixing through a complex 3D microfluidic device at 500 frames per second, the highest recorded in a magnetic resonance imaging experiment. The key to this development is combining remote detection with a time \&$\#$39;slicing\&$\#$39; of its spatially encoded counterpart. Remote detection circumvents the problem of insensitive direct MR detection on a microfluidic device where the direct sensitivity is less than 10(-5) relative to traditional NMR, while the time slicing eliminates the constraints of the limited observation time by converting the time variable into a spatial variable through the use of magnetic field gradients. This method has implications for observing fast processes, Such as fluid mixing, rapid binding, and certain classes of chemical reactions with sub millisecond time resolution and as a new modality for on-chip chromatography. Published by Elsevier Inc.

}, keywords = {probes}, isbn = {1090-7807}, doi = {Doi 10.1016/J.Jmr.2008.04.037}, url = {://WOS:000258357600005}, author = {Harel, E. and Pines, A.} } @article {274, title = {Submillimeter-resolution magnetic resonance imaging at the Earth{\textquoteright}s magnetic field with an atomic magnetometer}, journal = {Physical Review A}, volume = {78}, year = {2008}, note = {Phys Rev A333VGTimes Cited:18Cited References Count:24}, month = {Jul}, abstract = {

Magnetic resonance imaging in the Earth\&$\#$39;s magnetic field is achieved using a sensitive atomic magnetometer for detection. We demonstrate images with a submillimeter resolution by recording the flow of two water paths meeting at a T-shaped mixer. The high homogeneity of the Earth\&$\#$39;s field allows the use of weak gradient fields which circumvent the concomitant-field effect. To distinguish the two input channels, we employed selective polarization, which is a unique and noninvasive labeling method for low-field magnetic resonance imaging. Our technique imposes minimal physical constraints on the object under study, in contrast to conventional high-field magnetic resonance imaging. This technique is applicable for microfluidic imaging in laboratory-on-a-chip devices.

}, keywords = {nmr}, isbn = {1050-2947}, doi = {Doi 10.1103/Physreva.78.013404}, url = {://WOS:000258180300141}, author = {Xu, S. and Crawford, C. W. and Rochester, S. and Yashchuk, V. and Budker, D. and Pines, A.} } @article {276, title = {Temperature response of (129)Xe depolarization transfer and its application for ultrasensitive NMR detection}, journal = {Physical Review Letters}, volume = {100}, year = {2008}, note = {Phys Rev Lett320JWTimes Cited:12Cited References Count:8}, month = {Jun 27}, abstract = {

Trapping xenon in functionalized cryptophane cages makes the sensitivity of hyperpolarized (HP) (129)Xe available for specific NMR detection of biomolecules. Here, we study the signal transfer onto a reservoir of unbound HP xenon by gating the residence time of the nuclei in the cage through the temperature-dependant exchange rate. Temperature changes larger than similar to 0.6 K are detectable as an altered reservoir signal. The temperature response is adjustable with lower concentrations of caged xenon providing more sensitivity at higher temperatures. Ultrasensitive detection of functionalized cryptophane at 310 K is demonstrated with a concentration of 10 nM, corresponding to a similar to 4000-fold sensitivity enhancement compared to conventional detection. This makes HPNMR capable of detecting such constructs in concentrations far below the detection limit of benchtop uv-visible light absorbance.

}, keywords = {biosensors}, isbn = {0031-9007}, doi = {Doi 10.1103/Physrevlett.100.257603}, url = {://WOS:000257230500066}, author = {Schroeder, L. and Meldrum, T. and Smith, M. and Lowery, T. J. and Wemmer, D. E. and Pines, A.} } @article {277, title = {Temperature-controlled molecular depolarization gates in nuclear magnetic resonance}, journal = {Angewandte Chemie-International Edition}, volume = {47}, year = {2008}, note = {Angew Chem Int Edit308BXTimes Cited:13Cited References Count:19}, pages = {4316-4320}, keywords = {mri}, isbn = {1433-7851}, doi = {Doi 10.1002/Anie.200800382}, url = {://WOS:000256364400007}, author = {Schroder, L. and Chavez, L. and Meldrum, T. and Smith, M. and Lowery, T. J. and Wemmer, D. E. and Pines, A.} } @article {278, title = {Volume-selective magnetic resonance imaging using an adjustable, single-sided, portable sensor}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {105}, year = {2008}, note = {P Natl Acad Sci USA389LBTimes Cited:11Cited References Count:29}, month = {Dec 30}, pages = {20601-20604}, abstract = {

Portable, single-sided NMR sensors can operate under conditions inaccessible to conventional NMR while featuring lower cost, portability, and the ability to analyze arbitrary-sized objects. Such sensors can nondestructively probe the interior of samples by collecting images and measuring relaxation and diffusion constants, and, given careful shimming schemes, even perform chemical analysis. The inherently strong magnetic-field gradients of single-sided sensors developed so far has prevented imaging of materials with high water content, such as biological tissues, over large volumes whereas designs with more homogeneous fields suffer from low field strength and typically cannot probe volumes larger than approximate to 10 cm(3). We present a design with a continuously adjustable sensitive volume, enabling the effective volume to be enlarged several fold. This capability allows for imaging in reasonable times of much bigger objects and opens the door to the possibility of clinical imaging with portable sensors. We demonstrate MRI in axial and sagittal planes, at different depths of the sensitive volume and T(1)-weighted contrast in a tissue sample.

}, keywords = {xenon}, isbn = {0027-8424}, doi = {Doi 10.1073/Pnas.0811222106}, url = {://WOS:000262092800008}, author = {Paulsen, J. L. and Bouchard, L. S. and Graziani, D. and Blumich, B. and Pines, A.} } @article {279, title = {Zero-field remote detection of NMR with a microfabricated atomic magnetometer}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {105}, year = {2008}, note = {P Natl Acad Sci USA266XBTimes Cited:37Cited References Count:26}, month = {Feb 19}, pages = {2286-2290}, abstract = {

We demonstrate remote detection of nuclear magnetic resonance (NMR) with a microchip sensor consisting of a microfluidic channel and a microfabricated vapor cell (the heart of an atomic magnetometer). Detection occurs at zero magnetic field, which allows operation of the magnetometer in the spin-exchange relaxation-free (SERF) regime and increases the proximity of sensor and sample by eliminating the need for a solenoid to create a leading field. We achieve pulsed NMR linewidths of 26 Hz, limited, we believe, by the residence time and flow dispersion in the encoding region. In a fully optimized system, we estimate that for 1 s of integration, 7 x 10(13) protons in a volume of 1 mm(3), prepolarized in a 10-kG field, can be detected with a signal-to-noise ratio of approximate to 3. This level of sensitivity is competitive with that demonstrated by microcoils in 100-kG magnetic fields, without requiring superconducting magnets.

}, keywords = {mri}, isbn = {0027-8424}, doi = {Doi 10.1073/Pnas.0711505105}, url = {://WOS:000253469900009}, author = {Ledbetter, M. P. and Savukov, I. M. and Budker, D. and Shah, V. and Knappe, S. and Kitching, J. and Michalak, D. J. and Xu, S. and Pines, A.} } @article {284, title = {Design and construction of a contactless mobile RF coil for double resonance variable angle spinning NMR}, journal = {Journal of Magnetic Resonance}, volume = {188}, year = {2007}, note = {J Magn Reson214POTimes Cited:7Cited References Count:16}, month = {Sep}, pages = {183-189}, abstract = {

Variable angle spinning (VAS) experiments can be used to measure long-range dipolar couplings and provide structural information about molecules in oriented media. We present a probe design for this type of experiment using a contactless resonator. In this circuit, RF power is transmitted wirelessly via coaxial capacitive coupling where the coupling efficiency is improved by replacing the ordinary sample coil with a double frequency resonator. Our probe constructed out of this design principle has shown favorable properties at variable angle conditions. Moreover, a switched angle spinning correlation experiment is performed to demonstrate the probe\&$\#$39;s capability to resolve dipolar couplings in strongly aligned molecules. (c) 2007 Elsevier Inc. All rights reserved.

}, keywords = {magnetism}, isbn = {1090-7807}, doi = {Doi 10.1016/J.Jmr.2007.06.006}, url = {://WOS:000249750800020}, author = {Qian, C. Q. and Pines, A. and Martin, R. W.} } @article {288, title = {Dispersion measurements using time-of-flight remote detection MRI}, journal = {Magnetic Resonance Imaging}, volume = {25}, year = {2007}, note = {Magn Reson Imaging167BHTimes Cited:5Cited References Count:10}, month = {May}, pages = {449-452}, abstract = {

Remote detection nuclear magnetic resonance and magnetic resonance imaging can be used to study fluid flow and dispersion in a porous medium from a purely Eulerian point of view (i.e., in a laboratory frame of reference). Information about fluid displacement is obtained on a macroscopic scale in a long-time regime, while local velocity distributions are averaged out. It is shown how these experiments can be described using the common flow propagator formalism and how experimental data can be analyzed to obtain effective porosity, flow velocity inside the porous medium, fluid dispersion and flow tracing of fluid. (C) 2007 Elsevier Inc. All rights reserved.

}, keywords = {flow}, isbn = {0730-725X}, doi = {Doi 10.1016/J.Mri.2006.11.011}, url = {://WOS:000246425100004}, author = {Granwehr, J. and Harel, E. and Hilty, C. and Garcia, S. and Chavez, L. and Pines, A. and Sen, P. N. and Song, Y. Q.} } @article {286, title = {Multipole shimming of permanent magnets using harmonic corrector rings}, journal = {Review of Scientific Instruments}, volume = {78}, year = {2007}, note = {Rev Sci Instrum151WETimes Cited:8Cited References Count:8}, month = {Mar}, abstract = {

Shimming systems are required to provide sufficient field homogeneity for high resolution nuclear magnetic resonance (NMR). In certain specialized applications, such as rotating-field NMR and mobile ex situ NMR, permanent magnet-based shimming systems can provide considerable advantages. We present a simple two-dimensional shimming method based on harmonic corrector rings which can provide arbitrary multipole order shimming corrections. Results demonstrate, for example, that quadrupolar order shimming improves the linewidth by up to an order of magnitude. An additional order of magnitude reduction is in principle achievable by utilizing this shimming method for z-gradient correction and higher order xy gradients. (c) 2007 American Institute of Physics.

}, keywords = {field}, isbn = {0034-6748}, doi = {Doi 10.1063/1.2713438}, url = {://WOS:000245320800056}, author = {Jachmann, R. C. and Trease, D. R. and Bouchard, L. S. and Sakellariou, D. and Martin, R. W. and Schlueter, R. D. and Budinger, T. F. and Pines, A.} } @article {290, title = {Para-hydrogen-enhanced hyperpolarized gas-phase magnetic resonance imaging}, journal = {Angewandte Chemie-International Edition}, volume = {46}, year = {2007}, note = {Angew Chem Int Edit174ZPTimes Cited:28Cited References Count:37}, pages = {4064-4068}, keywords = {he-3}, isbn = {1433-7851}, doi = {Doi 10.1002/Anie.200700830}, url = {://WOS:000246981900008}, author = {Bouchard, L. S. and Kovtunov, K. V. and Burt, S. R. and Anwar, M. S. and Koptyug, I. V. and Sagdeev, R. Z. and Pines, A.} } @article {285, title = {Para-hydrogen-induced polarization in heterogeneous hydrogenation reactions}, journal = {Journal of the American Chemical Society}, volume = {129}, year = {2007}, note = {J Am Chem Soc160MRTimes Cited:36Cited References Count:45}, month = {May 2}, pages = {5580-5586}, abstract = {

We demonstrate the creation and observation of para-hydrogen-induced polarization in heterogeneous hydrogenation reactions. Wilkinson\&$\#$39;s catalyst, RhCl(PPh3)(3), supported on either modified silica gel or a polymer, is shown to hydrogenate styrene into ethylbenzene and to produce enhanced spin polarizations, observed through NMR, when the reaction was performed with H-2 gas enriched in the para spin isomer. Furthermore, gaseous phase para-hydrogenation of propylene to propane with two catalysts, the Wilkinson\&$\#$39;s catalyst supported on modified silica gel and Rh(cod)(sulfos) (cod = cycloocta-1,5-diene; sulfos = -O3S(C6H4)CH2C(CH2PPh2)(3)) supported on silica gel, demonstrates heterogeneous catalytic conversion resulting in large spin polarizations. These experiments serve as a direct verification of the mechanism of heterogeneous hydrogenation reactions involving immobilized metal complexes and can be potentially developed into a practical tool for producing catalyst-free fluids with highly polarized nuclear spins for a broad range of hyperpolarized NMR and MRI applications.

}, keywords = {alignment}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja068653o}, url = {://WOS:000245946400064}, author = {Koptyug, I. V. and Kovtunov, K. V. and Burt, S. R. and Anwar, M. S. and Hilty, C. and Han, S. I. and Pines, A. and Sagdeev, R. Z.} } @article {283, title = {Quantifying the diffusion of a fluid through membranes by double phase encoded remote detection magnetic resonance imaging}, journal = {Journal of Physical Chemistry B}, volume = {111}, year = {2007}, note = {J Phys Chem B240VDTimes Cited:11Cited References Count:31}, month = {Dec 20}, pages = {13929-13936}, abstract = {

We demonstrate that a position correlation magnetic resonance imaging (MRI) experiment based on two phase encoding steps separated by a delay can be used for quantifying diffusion across a membrane. This method is noninvasive, and no tracer substance or concentration gradient across the membrane is required. Because, in typical membranes, the T-1 relaxation time of the fluid spins is usually much longer than the T-2 time, we developed and implemented a new position correlation experiment based on a stimulated spin-echo, in which the relaxation attenuation of the signal is dominated by T-1 instead of T-2. This enables using relatively long delays needed in the diffusion measurements. The sensitivity of the double encoded experiment detected in a conventional way is still low because of the low filling factor of the fluid inside the NMR coil around the sample. We circumvent this problem by using the remote detection technique, which significantly increases the sensitivity, making it possible to do the measurements with gaseous fluids that have a low spin-density compared to liquids. We derive a model that enables us to extract a diffusion constant characterizing the diffusion rate through the membrane from the obtained correlation images. The double phase encoded MRI method is advantageous in any kind of diffusion studies, because the propagator of fluid molecules can directly be seen from the correlation image.

}, keywords = {mri}, isbn = {1520-6106}, doi = {Doi 10.1021/Jp076760e}, url = {://WOS:000251615400011}, author = {Telkki, V. V. and Hilty, C. and Garcia, S. and Harel, E. and Pines, A.} } @article {289, title = {Sensitivity enhancement by exchange mediated magnetization transfer of the xenon biosensor signal}, journal = {Journal of Magnetic Resonance}, volume = {184}, year = {2007}, note = {J Magn Reson127EUTimes Cited:7Cited References Count:18}, month = {Jan}, pages = {72-77}, abstract = {

Hyperpolarized xenon associated with ligand derivatized cryptophane-A cages has been developed as a NMR based biosensor. To optimize the detection sensitivity we describe use of xenon exchange between the caged and bulk dissolved xenon as an effective signal amplifier. This approach, somewhat analogous to \&$\#$39;remote detection\&$\#$39; described recently, uses the chemical exchange to repeatedly transfer spectroscopic information from caged to bulk xenon, effectively integrating the caged signal. After an optimized integration period, the signal is read out by observation of the bulk magnetization. The spectrum of the caged xenon is reconstructed through use of a variable evolution period before transfer and Fourier analysis of the bulk signal as a function of the evolution time. (c) 2006 Elsevier Inc. All rights reserved.

}, keywords = {resonance}, isbn = {1090-7807}, doi = {Doi 10.1016/J.Jmr.2006.09.010}, url = {://WOS:000243568900009}, author = {Garcia, S. and Chavez, L. and Lowery, T. J. and Han, S. I. and Wemmer, D. E. and Pines, A.} } @article {291, title = {Spin coherence transfer in chemical transformations monitored by remote detection NMR}, journal = {Analytical Chemistry}, volume = {79}, year = {2007}, note = {Anal Chem151QATimes Cited:7Cited References Count:39}, month = {Apr 1}, pages = {2806-2811}, abstract = {

We demonstrate a nuclear magnetic resonance (NMR) experiment using continuous flow in a microfluidic channel for studying the transfer of spin coherence in nonequilibrium chemical processes. We use the principle of remote detection, which involves spatially separated NMR encoding and detection coils. As an example, we provide the map of chemical shift correlations for the amino acid alanine as it transitions from the zwitterionic to the anionic form. The presented method uniquely allows for tracking the migration of encoded spins during the course of any chemical transformation and can provide useful information about reaction mechanisms.

}, keywords = {lab}, isbn = {0003-2700}, doi = {Doi 10.1021/Ac062327+}, url = {://WOS:000245304300022}, author = {Anwar, M. S. and Hilty, C. and Chu, C. and Bouchard, L. S. and Pierce, K. L. and Pines, A.} } @article {287, title = {Time-of-flight flow imaging of two-component flow inside a microfluidic chip}, journal = {Physical Review Letters}, volume = {98}, year = {2007}, note = {Phys Rev Lett124OYTimes Cited:21Cited References Count:16}, month = {Jan 5}, abstract = {

Here we report on using NMR imaging and spectroscopy in conjunction with time-of-flight tracking to noninvasively tag and monitor nuclear spins as they flow through the channels of a microfluidic chip. Any species with resolvable chemical-shift signatures can be separately monitored in a single experiment, irrespective of the optical properties of the fluids, thereby eliminating the need for foreign tracers. This is demonstrated on a chip with a mixing geometry in which two fluids converge from separate channels, and is generally applicable to any microfluidic device through which fluid flows within the nuclear spin-lattice relaxation time.

}, keywords = {microchannels}, isbn = {0031-9007}, doi = {Doi 10.1103/Physrevlett.98.017601}, url = {://WOS:000243379700050}, author = {Harel, E. and Hilty, C. and Koen, K. and McDonnell, E. E. and Pines, A.} } @article {293, title = {Application of atomic magnetometry in magnetic particle detection}, journal = {Applied Physics Letters}, volume = {89}, year = {2006}, note = {Appl Phys Lett112PJTimes Cited:9Cited References Count:18}, month = {Nov 27}, abstract = {

The authors demonstrate the detection of magnetic particles carried by water in a continuous flow using an atomic magnetic gradiometer. Studies on three types of magnetic particles are presented: a single cobalt particle (diameter similar to 150 mu m, multidomain), a suspension of superparamagnetic magnetite particles (diameter similar to 1 mu m), and ferromagnetic cobalt nanoparticles (diameter similar to 10 nm). Estimated detection limits are 20 mu m diameter for a single cobalt particle at a water flow rate of 30 ml/min, 5x10(3) magnetite particles at 160 ml/min, and 50 pl for the ferromagnetic fluid of cobalt nanoparticles at 130 ml/min. Possible applications of their method are discussed.

}, keywords = {system}, isbn = {0003-6951}, doi = {Doi 10.1063/1.2400077}, url = {://WOS:000242538500151}, author = {Xu, S. and Donaldson, M. H. and Pines, A. and Rochester, S. M. and Budker, D. and Yashchuk, V. V.} } @article {304, title = {Auxiliary probe design adaptable to existing probes for remote detection NMR, MRI, and time-of-flight tracing}, journal = {Journal of Magnetic Resonance}, volume = {182}, year = {2006}, note = {J Magn Reson093XPTimes Cited:7Cited References Count:21}, month = {Oct}, pages = {260-272}, abstract = {

A versatile, detection-only probe design is presented that can be adapted to any existing NMR or MRI probe with the purpose of making the remote detection concept generally applicable. Remote detection suggests freeing the NMR experiment from the confinement of using the same radio frequency (RF) coil and magnetic field for both information encoding and signal detection. Information is stored during the encoding step onto a fluid sensor medium whose magnetization is later measured in a different location. The choice of an RF probe and magnetic field for encoding can be made based solely on the size and characteristics of the sample and the desired information quality without considering detection sensitivity, as this aspect is dealt with by a separate detector. While early experiments required building probes that included two resonant circuits, one for encoding and one for detection, a modular approach with a detection-only probe as presented here can be used along with any existing NMR probe of choice for encoding. The design of two different detection-only probes is presented, one with a saddle coil for milliliter-sized detection volumes, and the other one with a microsolenoid coil for sub-microliter fluid quantities. As example applications, we present time-of-flight (TOF) tracing of hyperpolarized Xe-129 spins in a gas mixture through coiled tubing using the microsolenoid coil detector and TOF flow imaging through a nested glass container where the gas flow changes its direction twice between inlet and outlet using the saddle coil detector. (c) 2006 Elsevier Inc. All rights reserved.

}, keywords = {flow}, isbn = {1090-7807}, doi = {Doi 10.1016/J.Jmr.2006.06.024}, url = {://WOS:000241203900010}, author = {Han, S. I. and Granwehr, J. and Garcia, S. and McDonnell, E. E. and Pines, A.} } @article {295, title = {Diastereomeric Xe chemical shifts in tethered cryptophane cages}, journal = {Journal of the American Chemical Society}, volume = {128}, year = {2006}, note = {J Am Chem Soc118KQTimes Cited:14Cited References Count:42}, month = {Dec 27}, pages = {16980-16988}, abstract = {

Cryptophane cages serve as host molecules to a Xe atom. Functionalization of cryptophane-A has permitted the development of Xe as a biosensor. Synthetic routes used to prepare cryptophanes result in racemic mixtures of the chiral cages. In the preparation of a tethered cryptophane-A cage for biosensor applications, some achiral and chiral substituents such as left-handed amino acids have been used. When the substituent is achiral, the NMR signal of the Xe atom in the functionalized cage in solution is a single isotropic peak, since the Xe shielding tensor components in the R and L cages differ by no more than the signs of the off-diagonal elements. Chiral substituents can split the cage-encapsulated Xe NMR signal into one or more sets of doublets, depending on the number of asymmetric centers in the substituent. We carry out quantum mechanical calculations of Xe nuclear magnetic shielding for the Xe atom at the same strategic position within an L cryptophane-A cage, under the influence of chiral potentials that represent for r or I substituents outside the cage. Calculations of the Xe shielding response in the Lr and LI diastereomeric pairs permit the prediction of the relative order of the Xe chemical shifts in solutions containing the RI and LI diastereomers. Where the substituent itself possesses two chiral centers, comparison of the calculated isotropic shielding responses in the Llr, Lrl, RIl, and Lrr systems, respectively, permits the prediction of the Xe spectrum of diastereomeric systems in solutions containing Llr, RIr, LIl, and RIl systems. Assignment of the peaks observed in the experimental Xe NMR spectra is therefore possible, without having to undertake the difficult synthetic route that produces a single optically pure enantiomer.

}, keywords = {chirality}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja066661z}, url = {://WOS:000242941600104}, author = {Ruiz, E. J. and Sears, D. N. and Pines, A. and Jameson, C. J.} } @article {296, title = {Erwin L Hahn - Scientist, Mentor, Friend}, journal = {Journal of Magnetic Resonance}, volume = {179}, year = {2006}, note = {J Magn Reson035CMTimes Cited:1Cited References Count:1}, month = {Mar}, pages = {5-7}, isbn = {1090-7807}, doi = {Doi 10.1016/J.Jmr.2006.01.012}, url = {://WOS:000236977600002}, author = {Pines, A.} } @article {292, title = {Magnetic resonance imaging with an optical atomic magnetometer}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {103}, year = {2006}, note = {P Natl Acad Sci USA077NITimes Cited:58Cited References Count:18}, month = {Aug 22}, pages = {12668-12671}, abstract = {

We report an approach for the detection of magnetic resonance imaging without superconducting magnets and cryogenics: optical atomic magnetometry. This technique possesses a high sensitivity independent of the strength of the static magnetic field, extending the applicability of magnetic resonance imaging to low magnetic fields and eliminating imaging artifacts associated with high fields. By coupling with a remote-detection scheme, thereby improving the filling factor of the sample, we obtained time-resolved flow images of water with a temporal resolution of 0.1 s and spatial resolutions of 1.6 mm perpendicular to the flow and 4.5 mm along the flow. Potentially inexpensive, compact, and mobile, our technique provides a viable alternative for MRI detection with substantially enhanced sensitivity and time resolution for various situations where traditional MRI is not optimal.

}, keywords = {gas}, isbn = {0027-8424}, doi = {Doi 10.1073/Pnas.0605396103}, url = {://WOS:000240035900006}, author = {Xu, S. J. and Yashchuk, V. V. and Donaldson, M. H. and Rochester, S. M. and Budker, D. and Pines, A.} } @article {294, title = {Molecular imaging using a targeted magnetic resonance hyperpolarized biosensor}, journal = {Science}, volume = {314}, year = {2006}, note = {Science096MWTimes Cited:109Cited References Count:20}, month = {Oct 20}, pages = {446-449}, abstract = {

A magnetic resonance approach is presented that enables high-sensitivity, high-contrast molecular imaging by exploiting xenon biosensors. These sensors link xenon atoms to specific biomolecular targets, coupling the high sensitivity of hyperpolarized nuclei with the specificity of biochemical interactions. We demonstrated spatial resolution of a specific target protein in vitro at micromolar concentration, with a readout scheme that reduces the required acquisition time by \>3300-fold relative to direct detection. This technique uses the signal of free hyperpolarized xenon to dramatically amplify the sensor signal via chemical exchange saturation transfer (CEST). Because it is similar to 10,000 times more sensitive than previous CEST methods and other molecular magnetic resonance imaging techniques, it marks a critical step toward the application of xenon biosensors as selective contrast agents in biomedical applications.

}, keywords = {agents}, isbn = {0036-8075}, doi = {Doi 10.1126/Science.1131847}, url = {://WOS:000241382500036}, author = {Schroder, L. and Lowery, T. J. and Hilty, C. and Wemmer, D. E. and Pines, A.} } @article {302, title = {Multiphase imaging of gas flow in a nanoporous material using remote-detection NMR}, journal = {Nature Materials}, volume = {5}, year = {2006}, note = {Nat Mater029AOTimes Cited:25Cited References Count:40}, month = {Apr}, pages = {321-327}, abstract = {

Pore structure and connectivity determine how microstructured materials perform in applications such as catalysis, fluid storage and transport, filtering or as reactors. We report a model study on silica aerogel using a time-of-flight magnetic resonance imaging technique to characterize the flow field and explain the effects of heterogeneities in the pore structure on gas flow and dispersion with Xe-129 as the gas-phase sensor. The observed chemical shift allows the separate visualization of unrestricted xenon and xenon confined in the pores of the aerogel. The asymmetrical nature of the dispersion pattern alludes to the existence of a stationary and a flow regime in the aerogel. An exchange time constant is determined to characterize the gas transfer between them. As a general methodology, this technique provides insights into the dynamics of flow in porous media where several phases or chemical species may be present.

}, keywords = {visualization}, isbn = {1476-1122}, doi = {Doi 10.1038/Nmat1598}, url = {://WOS:000236530400024}, author = {Harel, E. and Granwehr, J. and Seeley, J. A. and Pines, A.} } @article {303, title = {NMR velocity mapping of gas flow around solid objects}, journal = {Physical Review E}, volume = {74}, year = {2006}, note = {Phys Rev EPart 2069DJTimes Cited:4Cited References Count:31}, month = {Jul}, abstract = {

We present experimental visualizations of gas flow around solid blunt bodies by NMR imaging. NMR velocimetry is a model-free and tracer-free experimental means for quantitative and multi-dimensional flow visualization. Hyperpolarization of Xe-129 provided sufficient NMR signal to overcome the low density of the dilute gas phase, and its long coherence time allows for true velocity vector mapping. In this study, the diverging gas flow around and wake patterns immediately behind a sphere could be vectorally visualized and quantified. In a similar experiment, the flow over an aerodynamic model airplane body revealed a less disrupted flow pattern.

}, keywords = {wake}, isbn = {1539-3755}, doi = {Doi 10.1103/Physreve.74.016302}, url = {://WOS:000239425700044}, author = {Han, S. I. and Pierce, K. L. and Pines, A.} } @article {299, title = {Optimization of xenon biosensors for detection of protein interactions}, journal = {Chembiochem}, volume = {7}, year = {2006}, note = {Chembiochem003SDTimes Cited:39Cited References Count:25}, month = {Jan}, pages = {65-73}, abstract = {

Hyperpolarized Xe-129 NMR spectroscopy can detect the presence of specific low-concentration biomolecular analytes by means of a xenon biosensor that consists of a water-soluble, targeted cryptophane-A cage that encapsulates the xenon. In this work, we use the prototypical biotinylated xenon biosensor to determine the relationship between the molecular composition of the xenon biosensor and the characteristics of protein-bound resonances. The effects of diastereomer overlap, dipole-dipole coupling, chemical-shift anisotropy, xenon exchange, and biosensor conformotional exchange on the protein-bound biosensor signal were assessed. It was found that an optimal protein-bound biosensor signal can be obtained by minimizing the number of biosensor diastereomers and using a flexible linker of appropriate length. Both the line width and sensitivity of chemical shift to protein binding of the xenon biosensor were found to be inversely proportional to linker length.

}, keywords = {complexes}, isbn = {1439-4227}, doi = {Doi 10.1002/Cbic.200500327}, url = {://WOS:000234701000012}, author = {Lowery, T. J. and Garcia, S. and Chavez, L. and Ruiz, E. J. and Wu, T. and Brotin, T. and Dutasta, J. P. and King, D. S. and Schultz, P. G. and Pines, A. and Wemmer, D. E.} } @article {300, title = {Solid-state NMR structural studies of the fibril form of a mutant mouse prion peptide PrP89-143(P101L)}, journal = {Solid State Nuclear Magnetic Resonance}, volume = {29}, year = {2006}, note = {Solid State Nucl Mag999VATimes Cited:22Cited References Count:34}, month = {Feb}, pages = {183-190}, abstract = {

The peptide fragment 89-143 of the prion protein (carrying a P101L mutation) is biologically active in transgenic mice when in a fibrillar form. Injection of these fibrils into transgenic mice (expressing full length PrP with the P101L mutation) induces a neurodegenerative prion disease (Kaneko et al., J. Mol. Biol. 295 (2000) 997). Here we present solid-state NMR studies of PrP89-143(P101L) fibrils, probing the conformation of residues in the hydrophobic segment 112-124 with chemical shifts. The conformations of glycine residues were analyzed using doubly C-13 = 0 labeled peptides by two-dimensional (2D) double-quantum correlation, and double-quantum filtered dephasing distance measurements. MQ-NMR experiments were carried out to probe the relative alignment of the individual peptides fibrils. These NMR studies indicate that the 112-124 segment adopts an extended beta-sheet conformation, though not in a parallel, in register alignment. There is evidence for conformational variability at Gly 113. DQ correlation experiments provide useful information in regions with conformational heterogeneity. (c) 2005 Elsevier Inc. All rights reserved.

}, keywords = {identification}, isbn = {0926-2040}, doi = {Doi 10.1016/J.Ssnmr.2005.09.017}, url = {://WOS:000234417500020}, author = {Lim, K. H. and Nguyen, T. N. and Damo, S. M. and Mazur, T. and Ball, H. L. and Prusiner, S. B. and Pines, A. and Wemmer, D. E.} } @article {301, title = {Spectrally resolved magnetic resonance imaging of a xenon biosensor}, journal = {Angewandte Chemie-International Edition}, volume = {45}, year = {2006}, note = {Angew Chem Int Edit997CZTimes Cited:48Cited References Count:14}, pages = {70-73}, keywords = {delivery}, isbn = {1433-7851}, doi = {Doi 10.1002/Anie.200502693}, url = {://WOS:000234223900007}, author = {Hilty, C. and Lowery, T. J. and Wemmer, D. E. and Pines, A.} } @article {298, title = {SQUID-detected microtesla MRI in the presence of metal}, journal = {Journal of Magnetic Resonance}, volume = {179}, year = {2006}, note = {J Magn Reson035CMTimes Cited:36Cited References Count:23}, month = {Mar}, pages = {146-151}, abstract = {

In magnetic resonance imaging performed at fields of I T and above, the presence of a metal insert can distort the image because of susceptibility differences within the sample and modification of the radiofrequency fields by screening currents. Furthermore, it is not feasible to perform nuclear magnetic resonance (NMR) spectroscopy or acquire a magnetic resonance image if the sample is enclosed in a metal container. Both problems can be overcome by substantially lowering the NMR frequency. Using a microtesla imaging system operating at 2.8 kHz, with a superconducting quantum interference device as the signal detector, we have obtained distortion-free images of a phantom containing a titanium bar and three-dimensional images of an object enclosed in an aluminum can; in both cases high-field images are inaccessible. (c) 2005 Elsevier Inc. All rights reserved.

}, keywords = {nmr}, isbn = {1090-7807}, doi = {Doi 10.1016/J.Jmr.2005.11.005}, url = {://WOS:000236977600019}, author = {Mossle, M. and Han, S. I. and Myers, W. R. and Lee, S. K. and Kelso, N. and Hatridge, M. and Pines, A. and Clarke, J.} } @article {305, title = {Toward ex situ phase-encoded spectroscopic imaging}, journal = {Concepts in Magnetic Resonance Part B-Magnetic Resonance Engineering}, volume = {29B}, year = {2006}, note = {Concept Magn Reson B067JNTimes Cited:7Cited References Count:20}, month = {Aug}, pages = {137-144}, abstract = {

Spectroscopic imaging of a sample placed outside of both the radio frequency and the imaging gradient coils is presented. The sample is placed in a field with a permanent one-dimensional inhomogeneity. The imaging gradients used for phase encoding are designed to produce a static field that depends only on the transverse direction, uncoupling the effects associated with the single-sided nature of these coils. Two-dimensional imaging coupled with chemical shift information is obtained via the ex situ matching technique. Open-saddle geometry is used to match the static field profile for chemical shift information recovery. (C) 2006 Wiley Periodicals, Inc.

}, keywords = {probe}, isbn = {1552-5031}, doi = {Doi 10.1002/Cmr.B.20069}, url = {://WOS:000239298100004}, author = {Demas, V. and Meriles, C. and Sakellariou, D. and Han, S. I. and Reimer, J. and Pines, A.} } @article {297, title = {Xenon biosensor amplification via dendrimer-cage supramolecular constructs}, journal = {Journal of the American Chemical Society}, volume = {128}, year = {2006}, note = {J Am Chem Soc043HFTimes Cited:37Cited References Count:21}, month = {May 17}, pages = {6334-6335}, keywords = {chemistry}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja061735s}, url = {://WOS:000237590400033}, author = {Mynar, J. L. and Lowery, T. J. and Wemmer, D. E. and Pines, A. and Frechet, J. M. J.} } @article {313, title = {Distinguishing multiple chemotaxis Y protein conformations with laser-polarized Xe-129 NMR}, journal = {Protein Science}, volume = {14}, year = {2005}, note = {Protein Sci907SSTimes Cited:23Cited References Count:27}, month = {Apr}, pages = {848-855}, abstract = {

The chemical shift of the Xe-129 NMR signal has been shown to be extremely sensitive to the local environment around the atom and has been used to follow processes such as ligand binding by bacterial periplasmic binding proteins. Here we show that the Xe-129 shift can sense more subtle changes: magnesium binding, BeF3- activation, and peptide binding by the Escherichia coli chemotaxis Y protein. H-1-N-15 correlation spectroscopy and X-ray crystallography were used to identify two xenon-binding cavities in CheY that are primarily responsible for the shift changes. One site is near the active site, and the other is near the peptide binding site.

}, keywords = {cavity}, isbn = {0961-8368}, doi = {Doi 10.1110/Ps.041231005}, url = {://WOS:000227738900002}, author = {Lowery, T. J. and Doucleff, M. and Ruiz, E. J. and Rubin, S. M. and Pines, A. and Wemmer, D. E.} } @article {308, title = {High-resolution NMR spectroscopy with a portable single-sided sensor}, journal = {Science}, volume = {308}, year = {2005}, note = {Science931JTTimes Cited:89Cited References Count:7}, month = {May 27}, pages = {1279-1279}, keywords = {fields}, isbn = {0036-8075}, doi = {Doi 10.1126/Science.1108944}, url = {://WOS:000229482300037}, author = {Perlo, J. and Demas, V. and Casanova, F. and Meriles, C. A. and Reimer, J. and Pines, A. and Blumich, B.} } @article {312, title = {High-resolution nuclear magnetic resonance spectroscopy of biological tissues using projected magic angle spinning}, journal = {Magnetic Resonance in Medicine}, volume = {54}, year = {2005}, note = {Magnet Reson Med949DSTimes Cited:2Cited References Count:28}, month = {Aug}, pages = {253-257}, abstract = {

High-resolution NMR spectra of materials subject to anisotropic broadening are usually obtained by rotating the sample about the magic angle, which is 54.7 degrees to the static magnetic field. In projected magic angle spinning (p-MAS), the sample is spun about two angles, neither of which is the magic angle. This provides a method of obtaining isotropic spectra while spinning at shallow angles. The p-MAS experiment may be used in situations where spinning the sample at the magic angle is not possible due to geometric or other constraints, allowing the choice of spinning angle to be determined by factors such as the shape of the sample, rather than by the spin physics. The application of this technique to bovine tissue samples is demonstrated as a proof of principle for future biological or medical applications.

}, keywords = {field}, isbn = {0740-3194}, doi = {Doi 10.1002/Mrm.20585}, url = {://WOS:000230765700001}, author = {Martin, R. W. and Jachmann, R. C. and Sakellariou, D. and Nielsen, U. G. and Pines, A.} } @article {316, title = {Isotropic proton-detected local-field nuclear magnetic resonance in solids}, journal = {Journal of Chemical Physics}, volume = {122}, year = {2005}, note = {J Chem Phys899JFTimes Cited:1Cited References Count:31}, month = {Feb 15}, abstract = {

A nuclear magnetic resonance method is presented which produces linear, isotropic proton-detected local-field spectra for INS spin systems in powdered samples. The method, heteronuclear isotropic evolution (HETIE), refocuses the anisotropic portion of the heteronuclear dipolar coupling frequencies by evolving the system under a series of specially designed Hamiltonians and evolution pathways. The theory behind HETIE is presented along with experimental studies conducted on a powdered sample of ferrocene, demonstrating the methodology outlined in this paper. Applications of HETIE for use in structure determination in the solid state are discussed. (C) 2005 American Institute of Physics.

}, keywords = {spectra}, isbn = {0021-9606}, doi = {Doi 10.1063/1.1844296}, url = {://WOS:000227140000043}, author = {Havlin, R. H. and Walls, J. D. and Pines, A.} } @article {315, title = {Microfluidic gas-flow profiling using remote-detection NMR}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {102}, year = {2005}, note = {P Natl Acad Sci USA977NZTimes Cited:41Cited References Count:26}, month = {Oct 18}, pages = {14960-14963}, abstract = {

We have used nuclear magnetic resonance (NMR) to obtain spatially and temporally resolved profiles of gas flow in microfluidic devices. Remote detection of the NMR signal both overcomes the sensitivity limitation of NMR and enables time-of-flight measurement in addition to spatially resolved imaging. Thus, detailed insight is gained into the effects of flow, diffusion, and mixing in specific geometries. The ability for noninvasive measurement of microfluidic flow, without the introduction of foreign tracer particles, is unique to this approach and is important for the design and operation of microfluidic devices. Although here we demonstrate an application to gas flow, extension to liquids, which have higher density, is implicit.

}, keywords = {mri}, isbn = {0027-8424}, doi = {Doi 10.1073/Pnas.0507566102}, url = {://WOS:000232811800006}, author = {Hilty, C. and McDonnell, E. E. and Granwehr, J. and Pierce, K. L. and Han, S. I. and Pines, A.} } @article {311, title = {NMR analysis on microfluidic devices by remote detection}, journal = {Analytical Chemistry}, volume = {77}, year = {2005}, note = {Anal Chem995DDTimes Cited:25Cited References Count:36}, month = {Dec 15}, pages = {8109-8114}, abstract = {

We present a novel approach to perform high-sensitivity NMR imaging and spectroscopic analysis on microfluidic devices. The application of NMR, the most information-rich spectroscopic technique, to microfluidic devices remains a challenge because the inherently low sensitivity of NMR is aggravated by small fluid volumes leading to low NMR signal and geometric constraints resulting in poor efficiency for inductive detection. We address the latter by physically separating signal detection from encoding of information with remote detection. Thereby, we use a commercial imaging probe with sufficiently large diameter to encompass the entire device, enabling encoding of NMR information at any location on the chip. Because large-diameter coils are too insensitive for detection, we store the encoded information as longitudinal magnetization and flow it into the outlet capillary. There, we detect the signal with optimal sensitivity, using a solenoidal microcoil, and reconstruct the information encoded in the fluid. We present a generally applicable design for a detection-only microcoil probe that can be inserted into the bore of a commercial imaging probe. Using hyperpolarized Xe-129 gas, we show that this probe enables sensitive reconstruction of NMR spectroscopic information encoded by the large imaging probe while keeping the flexibility of a large coil.

}, keywords = {probes}, isbn = {0003-2700}, doi = {Doi 10.1021/Ac051320+}, url = {://WOS:000234079200034}, author = {McDonnell, E. E. and Han, S. L. and Hilty, C. and Pierce, K. L. and Pines, A.} } @article {318, title = {NMR detection using laser-polarized xenon as a dipolar sensor}, journal = {Journal of Magnetic Resonance}, volume = {176}, year = {2005}, note = {J Magn Reson972AITimes Cited:14Cited References Count:46}, month = {Oct}, pages = {125-139}, abstract = {

Hyperpolarized Xe-129 can be used as a sensor to indirectly detect NMR spectra of heteronuclei that are neither covalently bound nor necessarily in direct contact with the Xe atoms, but coupled through long-range intermolecular dipole-dipole interactions. To reintroduce long-range dipolar couplings the sample symmetry has to be broken. This can be done either by using an asymmetric sample arrangement, or by breaking the symmetry of the spin magnetization with field gradient pulses. Experiments are performed where only a small fraction of the available Xe-129 magnetization is used for each point, so that a single batch of xenon suffices for the point-by-point acquisition of a heteronuclear NMR spectrum. Examples with H-1 as the analyte nucleus show that these methods have the potential to obtain spectra with a resolution that is high enough to determine homonuclear J couplings. The applicability of this technique with remote detection is discussed. Published by Elsevier Inc.

}, keywords = {dynamics}, isbn = {1090-7807}, doi = {Doi 10.1016/J.Jmr.2005.05.013}, url = {://WOS:000232425800001}, author = {Granwehr, J. and Urban, J. T. and Trabesinger, A. H. and Pines, A.} } @article {307, title = {NMR in rotating magnetic fields: magic-angle field spinning}, journal = {Magnetic Resonance Imaging}, volume = {23}, year = {2005}, note = {Magn Reson ImagingSp. Iss. SI920ADTimes Cited:10Cited References Count:16}, month = {Feb}, pages = {295-299}, abstract = {

Magic-angle sample spinning is one of the cornerstones in high-resolution NMR of solid and semisolid materials. The technique enhances spectral resolution by averaging away rank 2 anisotropic spin interactions, thereby producing isotropic-like spectra with resolved chemical shifts and scalar couplings. In principle, it should be possible to induce similar effects in a static sample if the direction of the magnetic field is varied (e.g., magic-angle rotation of the B-0 field). Here we will review some recent experimental results that show progress toward this goal. Also, we will explore some alternative approaches that may enable the recovery of spectral resolution in cases where the field is rotating off the magic angle. Such a possibility could help mitigate the technical problems that render difficult the practical implementation of this method at moderately strong magnetic fields. (c) 2005 Elsevier Inc. All rights reserved.

}, keywords = {samples}, isbn = {0730-725X}, doi = {Doi 10.1016/J.Mri.2004.11.067}, url = {://WOS:000228658400030}, author = {Sakellariou, D. and Meriles, C. A. and Martin, R. W. and Pines, A.} } @article {306, title = {NMR spectroscopy in inhomogeneous B-0 and B-1 fields with non-linear correlation}, journal = {Journal of Magnetic Resonance}, volume = {175}, year = {2005}, note = {J Magn Reson939CPTimes Cited:8Cited References Count:38}, month = {Jul}, pages = {1-10}, abstract = {

Resolved NMR spectra from samples in inhomogeneous B-0 and B-1 fields can be obtained with the so-called \"ex situ\" methodology, employing a train of composite or adiabatic z-rotation RF pulses to periodically refocus the inhomogeneous broadening during the detection of the time-domain signal. Earlier schemes relied on a linear correlation between the inhomogeneous B0 and B, fields. Here the pulse length, bandwidth, and amplitude of the adiabatic pulses of the hyperbolic secant type are adjusted to improve the refocusing for a setup with non-linear correlation. The field correlation is measured using a two-dimensional nutation experiment augmented with a third dimension with varying RF carrier frequency accounting for off-resonance effects. The pulse optimization is performed with a computer algorithm using the experimentally determined field correlation and a standard adiabatic z-rotation pulse as a starting point for the iterative optimization procedure. The shape of the z-rotation RF pulse is manipulated to provide refocusing for the conditions given by the sample-, magnet-, and RF-coil geometry. (c) 2005 Elsevier Inc. All rights reserved.

}, keywords = {spectra}, isbn = {1090-7807}, doi = {Doi 10.1016/J.Jmr.2005.03.006}, url = {://WOS:000230050200001}, author = {Topgaard, D. and Sakellariou, D. and Pines, A.} } @article {317, title = {NMR-based biosensing with optimized delivery of polarized Xe-129 to solutions}, journal = {Analytical Chemistry}, volume = {77}, year = {2005}, note = {Anal Chem942GLTimes Cited:30Cited References Count:37}, month = {Jul 1}, pages = {4008-4012}, abstract = {

Laser-enhanced (LE) Xe-129 nuclear magnetic resonance (NMR) is an exceptional tool for sensing extremely small physical and chemical changes; however, the difficult mechanics of bringing polarized xenon and samples of interest together have limited applications, particularly to biological molecules. Here we present a method for accomplishing solution Xe-129 biosensing based on flow (bubbling) of LE Xe-129 gas through a solution in situ in the NMR probe, with pauses for data acquisition. This overcomes fundamental limitations of conventional solution-state LE Xe-129 NMR, e.g., the difficulty in transferring hydrophobic xenon into aqueous environments, and the need to handle the sample to refresh LE Xe-129 after an observation pulse depletes polarization. With this new method, we gained a factor of \> 100 in sensitivity due to improved xenon transfer to the solution and the ability to signal average by renewing the polarized xenon. Polarized xenon in biosensors was detected at very low concentrations, \<= 250 nanomolar, while retaining all the usual information from NMR. This approach can be used to simultaneously detect multiple sensors with different chemical shifts and is also capable of detecting signals from opaque, heterogeneous samples, which is a unique advantage over optical methods. This general approach is adaptable for sensing minute quantities of xenon in heterogeneous in vitro samples, in miniaturized devices and should be applicable to certain in-vivo environments.

}, keywords = {blood}, isbn = {0003-2700}, doi = {Doi 10.1021/Ac0500479}, url = {://WOS:000230270800035}, author = {Han, S. I. and Garcia, S. and Lowery, T. J. and Ruiz, E. J. and Seeley, J. A. and Chavez, L. and King, D. S. and Wemmer, D. E. and Pines, A.} } @article {309, title = {SQUID-detected in vivo MRI at microtesla magnetic fields}, journal = {Ieee Transactions on Applied Superconductivity}, volume = {15}, year = {2005}, note = {Ieee T Appl SuperconPart 1935FOTimes Cited:24Cited References Count:15}, month = {Jun}, pages = {757-760}, abstract = {

We use a low transition temperature (T(c)) Super-conducting Quantum Interference Device (SQUID) to perform in vivo magnetic resonance imaging (MRI) at magnetic fields around 100 microtesla, corresponding to proton Larmor frequencies of about 5 kHz. In such low fields, broadening of the nuclear magnetic resonance lines due to inhomogeneous magnetic fields and susceptibility variations of the sample are minimized, enabling us to obtain high quality images. To reduce environmental noise the signal is detected by a second-order gradiometer, coupled to the SQUID, and the experiment is surrounded by a 3-mm thick Al shield. To increase the signal-to-noise ratio (SNR), we prepolarize the samples in a field up to 100 mT. Three-dimensional images are acquired in less than 6 minutes with a standard spin-echo phase-encoding sequence. Using encoding gradients of similar to 100 mu T/m we obtain three-dimensional images of bell peppers with a resolution of 2 x 2 x 8 mm(3). Our system is ideally suited to acquiring images of small, peripheral parts of the human body such as hands and arms. In vivo images of an arm, acquired at 132 mu T, show 24-mm sections of the forearm with a resolution of 3 x 3 mm(2). and a SNR of 10. We discuss possible applications of MRI at these low magnetic fields.

}, keywords = {nmr}, isbn = {1051-8223}, doi = {Doi 10.1109/Tasc.2005.850043}, url = {://WOS:000229765300170}, author = {Mossle, M. and Myers, W. R. and Lee, S. K. and Kelso, N. and Hatridge, M. and Pines, A. and Clarke, J.} } @article {314, title = {SQUID-detected MRI at 132 mu T with T(1)-weighted contrast established at 10 mu T-300 mT}, journal = {Magnetic Resonance in Medicine}, volume = {53}, year = {2005}, note = {Magn Reson Med888NETimes Cited:73Cited References Count:20}, month = {Jan}, pages = {9-14}, abstract = {

T(1)-weighted contrast MRI with prepolarization was detected with a superconducting quantum interference device (SQUID). A spin evolution period in a variable field between prepolarization and detection enabled the measurement of T(1) in fields between 1.7 muT and 300 mT; T, dispersion curves of agarose gel samples over five decades in frequency were obtained. SQUID detection at 5.6 kHz drastically reduces the field homogeneity requirements compared to conventional field-cycling methods using Faraday coil detection. This allows T(1) dispersion measurements to be easily combined with MRI, so that T(1) in a wide range of fields can be used for tissue contrast. Images of gel phantoms with T(1)-weighted contrast at four different fields between 10 muT and 300 mT demonstrated dramatic contrast enhancement in low fields. A modified inversion recovery technique further enhanced the contrast by selectively suppressing the signal contribution for a specific value of the low-field T(1). Published 2004 Wiley-Liss, Inc.

}, keywords = {dispersion}, isbn = {0740-3194}, doi = {Doi 10.1002/Mrm.20316}, url = {://WOS:000226380700003}, author = {Lee, S. K. and Mossle, M. and Myers, W. and Kelso, N. and Trabesinger, A. H. and Pines, A. and Clarke, J.} } @article {319, title = {Time-of-flight flow imaging using NMR remote detection}, journal = {Physical Review Letters}, volume = {95}, year = {2005}, note = {Phys Rev Lett955SGTimes Cited:35Cited References Count:29}, month = {Aug 12}, abstract = {

A time-of-flight imaging technique is introduced to visualize fluid flow and dispersion through porous media using NMR. As the fluid flows through a sample, the nuclear spin magnetization is modulated by rf pulses and magnetic field gradients to encode the spatial coordinates of the fluid. When the fluid leaves the sample, its magnetization is recorded by a second rf coil. This scheme not only facilitates a time-dependent imaging of fluid flow, it also allows a separate optimization of encoding and detection subsystems to enhance overall sensitivity. The technique is demonstrated by imaging gas flow through a porous rock.

}, keywords = {mri}, isbn = {0031-9007}, doi = {Doi 10.1103/Physrevlett.95.075503}, url = {://WOS:000231247300028}, author = {Granwehr, J. and Harel, E. and Han, S. and Garcia, S. and Pines, A. and Sen, P. N. and Song, Y. Q.} } @article {320, title = {Xenon NMR as a probe for microporous and mesoporous solids, polymers, liquid crystals, solutions, flames, proteins, imaging}, journal = {Actualite Chimique}, year = {2005}, note = {Actual ChimiqueSuppl. 287952GHTimes Cited:3Cited References Count:89}, month = {Jun}, pages = {16-34}, abstract = {

We present in this paper some examples of the applications of the Nuclear Magnetic Resonance (NMR) of xenon used as a probe in the study of different chemical environments: determination of the porosity of micro-and mesoporous solids, evaluation of the concentrations and sizes of amorphous domains in solid polymers, characterization of liquid crystals, study of combustion processes at high temperature, determination of the structure and dynamics of organic systems and proteins in solution, assessment of cerebral blood flow.

}, keywords = {silica-gels}, isbn = {0151-9093}, url = {://WOS:000230991500005}, author = {Bartik, K. and Choquet, P. and Constantinesco, A. and Duhamel, G. and Fraissard, J. and Hyacinthe, J. N. and Jokisaari, J. and Locci, E. and Lowery, T. J. and Luhmer, M. and Meersmann, T. and Moudrakovski, I. L. and Pavlovskaya, G. E. and Pierce, K. L. and Pines, A. and Ripmeester, J. A. and Telkki, V. V. and Veeman, W. S.} } @article {310, title = {Zero- to low-field MRI with averaging of concomitant gradient fields}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {102}, year = {2005}, note = {P Natl Acad Sci USA898JKTimes Cited:18Cited References Count:22}, month = {Feb 8}, pages = {1840-1842}, abstract = {

Magnetic resonance imaging (MRI) encounters fundamental limits in circumstances in which the static magnetic field is not sufficiently strong to truncate unwanted, so-called concomitant components of the gradient field. This limitation affects the attainable optimal image fidelity and resolution most prominently in low-field imaging. in this article, we introduce the use of pulsed magnetic-field averaging toward relaxing these constraints. It is found that the image of an object can be retrieved by pulsed low fields in the presence of the full spatial variation of the imaging encoding gradient field even in the absence of the typical uniform high-field time-independent contribution. In addition, error-compensation schemes can be introduced through the application of symmetrized pulse sequences. Such schemes substantially mitigate artifacts related to evolution in strong magnetic-field gradients, magnetic fields that vary in direction and orientation, and imperfections of the applied field pulses.

}, keywords = {selection}, isbn = {0027-8424}, doi = {Doi 10.1073/Pnas.0409115102}, url = {://WOS:000227072900009}, author = {Meriles, C. A. and Sakellariou, D. and Trabesinger, A. H. and Demas, V. and Pines, A.} } @article {328, title = {Advances in ex-situ Nuclear Magnetic Resonance}, journal = {Comptes Rendus Physique}, volume = {5}, year = {2004}, note = {Cr Phys843JCTimes Cited:13Cited References Count:47}, month = {Apr}, pages = {337-347}, abstract = {

Nuclear Magnetic Resonance has revolutionized modern science by its precision, selectivity and non-envasiveness. From complicated biomolecules to materials, from living organisms to nanometric particles, Magnetic Resonance Imaging and Spectroscopy have provided a wealth of invaluable information. Those studies take place in the laboratory, since they require strong and extremely homogeneous superconducting magnets and this represents a major limitation for the technique. Furthermore, the size of the object or subject to study is limited since it has to fit inside the bore of the magnet. Efforts to alleviate those problems lead to the recent development of portable magnetic resonance systems. Their use remained, however, mainly qualitative, since spectroscopic information could not be recovered. We have introduced recently an approach to regain this lost spectral information even in the presence of inhomogeneous magnetic fields. Our approach is based on the matching between the effect of the radio-frequency field and the effect of the static magnetic field. Several practical implementations will be reviewed and put in perspective for their applicability and efficiency in ex-situ NMR. (C) 2004 Academie des sciences. Published by Elsevier SAS. All rights reserved.

}, keywords = {in-vivo}, isbn = {1631-0705}, doi = {Doi 10.1016/J.Crhy.2004.03.016}, url = {://WOS:000223073800006}, author = {Sakellariou, D. and Meriles, C. A. and Pines, A.} } @article {333, title = {Design of a conformation-sensitive xenon-binding cavity in the ribose-binding protein}, journal = {Angewandte Chemie-International Edition}, volume = {43}, year = {2004}, note = {Angew Chem Int Edit877MVTimes Cited:10Cited References Count:20}, pages = {6320-6322}, keywords = {probe}, isbn = {1433-7851}, doi = {Doi 10.1002/Anie.200460629}, url = {://WOS:000225575600015}, author = {Lowery, T. J. and Rubin, S. M. and Ruiz, E. J. and Pines, A. and Wemmer, D. E.} } @article {325, title = {Development of a functionalized xenon biosensor}, journal = {Journal of the American Chemical Society}, volume = {126}, year = {2004}, note = {J Am Chem Soc872UHTimes Cited:60Cited References Count:76}, month = {Nov 24}, pages = {15287-15294}, abstract = {

NMR-based biosensors that utilize laser-polarized xenon offer potential advantages beyond current sensing technologies. These advantages include the capacity to simultaneously detect multiple analytes, the applicability to in vivo spectroscopy and imaging, and the possibility of \"remote\" amplified detection. Here, we present a detailed NMR characterization of the binding of a biotin-derivatized caged-xenon sensor to avidin. Binding of \"functionalized\" xenon to avidin leads to a change in the chemical shift of the encapsulated xenon in addition to a broadening of the resonance, both of which serve as NMR markers of ligand-target interaction. A control experiment in which the biotin-binding site of avidin was blocked with native biotin showed no such spectral changes, confirming that only specific binding, rather than nonspecific contact, between avidin and functionalized xenon leads to the effects on the xenon NMR spectrum. The exchange rate of xenon (between solution and cage) and the xenon spin-lattice relaxation rate were not changed significantly upon binding. We describe two methods for enhancing the signal from functionalized xenon by exploiting the laser-polarized xenon magnetization reservoir. We also show that the xenon chemical shifts are distinct for xenon encapsulated in different diastereomeric cage molecules. This demonstrates the potential for tuning the encapsulated xenon chemical shift, which is a key requirement for being able to multiplex the biosensor.

}, keywords = {drug discovery}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja0483037}, url = {://WOS:000225233600051}, author = {Spence, M. M. and Ruiz, E. J. and Rubin, S. M. and Lowery, T. J. and Winssinger, N. and Schultz, P. G. and Wemmer, D. E. and Pines, A.} } @article {335, title = {Diamagnetic clusters of paramagnetic endometallofullerenes: A solid-state MAS NMR study}, journal = {Journal of Physical Chemistry B}, volume = {108}, year = {2004}, note = {J Phys Chem B846BKTimes Cited:10Cited References Count:39}, month = {Aug 19}, pages = {12450-12455}, abstract = {

Solid powder samples of complexes of the endometallofullerenes (EMF) La@C-82 and Y@C-82 with hexamethylphosphoramide (HMPA) were studied by magic-angle spinning (MAS) NMR. We have obtained well-resolved P-31 NMR spectra and C-13 NMR spectra for both La-EMF/HMPA and Y-EMF/HMPA and La-139 spectra for the La-EMF/HMPA. The (31)p measurements on La-EMF/HMPA and Y-EMF/HMPA have revealed considerable chemical shifts of (31)p signals relative to pure HMPA. Two-dimensional exchange P-31 experiments revealed that HMPA molecules at different sites in the EMF/HMPA complex do not change positions at a time scale of up to 1 s. Both EMF samples demonstrate a vast chemical shift range for 31p of the bound HMPA molecules. In addition, the La-EMF/HMPA exhibits the enormous spreading of the chemical shifts for La-139. The experimental results suggest that paramagnetic La@C-82 and Y@C-92 in the solid state form clusters (nanoparticles) in which the exchange coupling of the EMF takes place with quenching of the most electron spins.

}, keywords = {complexes}, isbn = {1520-6106}, doi = {Doi 10.1021/Jp048610z}, url = {://WOS:000223289500027}, author = {Koltover, V. K. and Logan, J. W. and Heise, H. and Bubnov, V. P. and Estrin, Y. I. and Kareev, I. E. and Lodygina, V. P. and Pines, A.} } @article {330, title = {High-resolution NMR of static samples by rotation of the magnetic field}, journal = {Journal of Magnetic Resonance}, volume = {169}, year = {2004}, note = {J Magn Reson830ZETimes Cited:13Cited References Count:24}, month = {Jul}, pages = {13-18}, abstract = {

Mechanical rotation of a sample at 54.7degrees with respect to the static magnetic field, so-called magic-angle spinning (MAS), is currently a routine procedure in nuclear magnetic resonance (NMR). The technique enhances the spectral resolution by averaging away anisotropic spin interactions thereby producing isotropic-like spectra with resolved chemical shifts and scalar Couplings. It should be possible to induce similar effects in a static sample if the direction of the magnetic field is varied, e.g., magic-angle rotation of the B-0 field (B-0-MAS). Here, this principle is experimentally demonstrated in a static sample of solid hyperpolarized xenon at similar to3.4mT. By extension to moderately high fields, it is possible to foresee interesting applications in situations where physical manipulation of the sample is inconvenient or impossible. Such situations are expected to arise in many cases from materials to biomedicine and are particularly relevant to the novel approach of ex situ NMR spectroscopy and imaging. (C) 2004 Elsevier Inc. All rights reserved.

}, keywords = {hz}, isbn = {1090-7807}, doi = {Doi 10.1016/J.Jmr.2004.03.023}, url = {://WOS:000222161900002}, author = {Meriles, C. A. and Sakellariou, D. and Moule, A. and Goldman, M. and Budinger, T. F. and Pines, A.} } @article {321, title = {Hyperpolarized xenon nuclear spins detected by optical atomic magnetometry}, journal = {Physical Review Letters}, volume = {93}, year = {2004}, note = {Phys Rev Lett863ATTimes Cited:32Cited References Count:22}, month = {Oct 15}, abstract = {

We report the use of an atomic magnetometer based on nonlinear magneto-optical rotation with frequency-modulated light to detect nuclear magnetization of xenon gas. The magnetization of a spin-exchange-polarized xenon sample (1.7 cm(3) at a pressure of 5 bars, natural isotopic abundance, polarization 1\%), prepared remotely to the detection apparatus, is measured with an atomic sensor. An average magnetic field of similar to10 nG induced by the xenon sample on the 10 cm diameter atomic sensor is detected with signal-to-noise ratio similar to10, limited by residual noise in the magnetic environment. The possibility of using modern atomic magnetometers as detectors of nuclear magnetic resonance and in magnetic resonance imaging is discussed. Atomic magnetometers appear to be ideally suited for emerging low-field and remote-detection magnetic resonance applications.

}, keywords = {mri}, isbn = {0031-9007}, doi = {Doi 10.1103/Physrevlett.93.160801}, url = {://WOS:000224533300012}, author = {Yashchuk, V. V. and Granwehr, J. and Kimball, D. F. and Rochester, S. M. and Trabesinger, A. H. and Urban, J. T. and Budker, D. and Pines, A.} } @article {334, title = {Isotropic-liquid crystalline phase diagram of a CdSe nanorod solution}, journal = {Journal of Chemical Physics}, volume = {120}, year = {2004}, note = {J Chem Phys763JETimes Cited:27Cited References Count:29}, month = {Jan 15}, pages = {1149-1152}, abstract = {

We report the isotropic-liquid crystalline phase diagram of 3.0 nm x 60 nm CdSe nanorods dispersed in anhydrous cyclohexane. The coexistence concentrations of both phases are found to be lower and the biphasic region wider than the results predicted by the hard rod model, indicating that the attractive interaction between the nanorods may be important in the formation of the liquid crystalline phase in this system. (C) 2004 American Institute of Physics.

}, keywords = {model}, isbn = {0021-9606}, doi = {Doi 10.1063/1.1640331}, url = {://WOS:000188081000002}, author = {Li, L. S. and Marjanska, M. and Park, G. H. J. and Pines, A. and Alivisatos, A. P.} } @article {331, title = {Microtesla MRI with a superconducting quantum interference device}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {101}, year = {2004}, note = {P Natl Acad Sci USA823ZCTimes Cited:76Cited References Count:29}, month = {May 25}, pages = {7857-7861}, abstract = {

MRI scanners enable fast, noninvasive, and high-resolution imaging of organs and soft tissue. The images are reconstructed from NMR signals generated by nuclear spins that precess in a static magnetic field B(0) in the presence of magnetic field gradients. Most clinical MRI scanners operate at a magnetic field B(0) = 1.5 T, corresponding to a proton resonance frequency of 64 MHz. Because these systems rely on large superconducting magnets, they are costly and demanding of infrastructure. On the other hand, low-field imagers have the potential to be less expensive, less confining, and more mobile. The major obstacle is the intrinsically low sensitivity of the low-field NMR experiment. Here, we show that prepolarization of the nuclear spins and detection with a superconducting quantum interference device (SQUID) yield a signal that is independent of B(0), allowing acquisition of high-resolution MRIs in microtesla fields. Reduction of the strength of the measurement field eliminates inhomogeneous broadening of the NMR lines, resulting in enhanced signal-to-noise ratio and spatial resolution for a fixed strength of the magnetic field gradients used to encode the image. We present high-resolution images of phantoms and other samples and T(1)-weighted contrast images acquired in highly inhomogeneous magnetic fields of 132 muT; here, T, is the spin-lattice relaxation time. These techniques could readily be adapted to existing multichannel SQUID systems used for magnetic source imaging of brain signals. Further potential applications include low-cost systems for tumor screening and imaging peripheral regions of the body.

}, keywords = {system}, isbn = {0027-8424}, doi = {Doi 10.1073/Pnas.0402382101}, url = {://WOS:000221652000005}, author = {McDermott, R. and Lee, S. K. and ten Haken, B. and Trabesinger, A. H. and Pines, A. and Clarke, J.} } @article {326, title = {NMR studies of C-13-iodomethane: Different behavior in thermotropic and lyotropic liquid crystals}, journal = {Journal of Physical Chemistry A}, volume = {108}, year = {2004}, note = {J Phys Chem A846BMTimes Cited:9Cited References Count:38}, month = {Aug 19}, pages = {6809-6813}, abstract = {

High-resolution NMR spectra of C-13-iodomethane dissolved in thermotropic and lyotropic liquid crystalline solvents have been used to measure H-1-H-1 and C-13-H-1 dipolar couplings. The ratio of these two couplings, which is a function of the H-C-H bond angle in C-13-iodomethane, is, in general, different from that expected from the known molecular structure; solvent-solute interactions in liquid crystalline solutions are responsible for this difference. In thermotropic liquid crystalline solutions, the apparent bond angle deviation (Deltatheta(a)) increases with decreasing molecular ordering. In contrast, in lyotropic liquid crystals, no significant spectral aberration has been observed. These results indicate a fundamental physicochemical difference between the intermolecular interactions that prevail in thermotropic and lyotropic liquid crystals.

}, keywords = {biomolecules}, isbn = {1089-5639}, doi = {Doi 10.1021/Jp047330g}, url = {://WOS:000223289700001}, author = {Shahkhatuni, A. G. and Shahkhatuni, A. A. and Panosyan, H. A. and Park, G. H. J. and Martin, R. W. and Pines, A.} } @article {337, title = {Rational reduction of periodic propagators for off-period observations}, journal = {Journal of Magnetic Resonance}, volume = {166}, year = {2004}, note = {J Magn Reson767TUTimes Cited:2Cited References Count:19}, month = {Feb}, pages = {174-181}, abstract = {

Many common solid-state nuclear magnetic resonance problems take advantage of the periodicity of the underlying Hamiltonian to simplify the computation of an observation. Most of the time-domain methods used, however, require the time step between observations to be some integer or reciprocal-integer multiple of the period, thereby restricting the observation bandwidth. Calculations of off-period observations are usually reduced to brute force direct methods resulting in many demanding matrix multiplications. For large spin systems, the matrix multiplication becomes the limiting step. A simple method that can dramatically reduce the number of matrix multiplications required to calculate the time evolution when the observation time step is some rational fraction of the period of the Hamiltonian is presented. The algorithm implements two different optimization routines. One uses pattern matching and additional memory storage, while the other recursively generates the propagators via time shifting. The net result is a significant speed improvement for some types of time-domain calculations. (C) 2003 Published by Elsevier Inc.

}, keywords = {simulation}, isbn = {1090-7807}, doi = {Doi 10.1016/J.Jmr.2003.10.002}, url = {://WOS:000188469400005}, author = {Blanton, W. B. and Logan, J. W. and Pines, A.} } @article {327, title = {Remotely detected high-field MRI of porous samples}, journal = {Journal of Magnetic Resonance}, volume = {167}, year = {2004}, note = {J Magn Reson809KKTimes Cited:26Cited References Count:28}, month = {Apr}, pages = {282-290}, abstract = {

Remote detection of NMR is a novel technique in which an NMR-active sensor surveys an environment of interest and retains memory of that environment to be recovered at a later time in a different location. The NMR or MRI information about the sensor nucleus is encoded and stored as spin polarization at the first location and subsequently moved to a different physical location for optimized detection. A dedicated probe incorporating two separate radio frequency (RF)-circuits was built for this purpose. The encoding solenoid coil was large enough to fit around the bulky sample matrix, while the smaller detection solenoid coil had not only a higher quality factor, but also an enhanced filling factor since the coil volume comprised purely the sensor nuclei. We obtained two-dimensional (2D) void space images of two model porous samples with resolution less than 1.4 mm(2). The remotely reconstructed images demonstrate the ability to determine fine structure with image quality superior to their directly detected counterparts and show the great potential of NMR remote detection for imaging applications that suffer from low sensitivity due to low concentrations and filling factor. Published by Elsevier Inc.

}, keywords = {gas}, isbn = {1090-7807}, doi = {Doi 10.1016/J.Jmr.2003.12.018}, url = {://WOS:000220635400012}, author = {Seeley, J. A. and Han, S. I. and Pines, A.} } @article {323, title = {Self-diffusion measurements with chemical shift resolution in inhomogeneous magnetic fields}, journal = {Journal of Magnetic Resonance}, volume = {168}, year = {2004}, note = {J Magn Reson814XETimes Cited:5Cited References Count:27}, month = {May}, pages = {31-35}, abstract = {

A methodology for chemical shift resolved molecular self-diffusion measurements in time-independent static and radiofrequency field gradients is demonstrated. Diffusion encoding is provided by a stimulated echo Sequence with additional z-storage that allows for a change of diffusion time Without affecting the relaxation weighting. The signal is acquired stroboscopically between the pulses of a train of adiabatic double passages that induces a z-rotation Counteracting the phase spread resulting from precession in the inhomogeneous static field. as demonstrated in recent approaches to the goal of high-resolution \"ex situ\" NMR. Simulations of the pulse sequence show that the acquired signal results from the desired coherence pathway. Successful demonstrations of the experiment were performed on a Mixture of water and isopropanol. Published by Elsevier Inc.

}, keywords = {excitation}, isbn = {1090-7807}, doi = {Doi 10.1016/J.Jmr.2004.01.018}, url = {://WOS:000221006600004}, author = {Topgaard, D. and Pines, A.} } @article {324, title = {"Shim pulses" for NMR spectroscopy and imaging}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {101}, year = {2004}, note = {P Natl Acad Sci USA882PTTimes Cited:38Cited References Count:16}, month = {Dec 21}, pages = {17576-17581}, abstract = {

A way to use adiabatic radiofrequency pulses and modulated magnetic-field gradient pulses, together constituting a \"shim pulse,\" for NMR spectroscopy and imaging is demonstrated. These pulses capitalize on phase shifts derived from probe gradient coils to compensate for nonlinear intrinsic main magnetic field homogeneity for spectroscopy, as well as for deviations from linear gradients for imaging. This approach opens up the possibility of exploiting cheaper, less-than-perfect magnets and gradient coils for NMR applications.

}, keywords = {acquisition}, isbn = {0027-8424}, doi = {Doi 10.1073/Pnas.0408296102}, url = {://WOS:000225951500004}, author = {Topgaard, D. and Martin, R. W. and Sakellariou, D. and Meriles, C. A. and Pines, A.} } @article {322, title = {SQUID-detected liquid state NMR in microtesla fields}, journal = {Journal of Physical Chemistry A}, volume = {108}, year = {2004}, note = {J Phys Chem A772FTTimes Cited:32Cited References Count:36}, month = {Feb 12}, pages = {957-963}, abstract = {

Nuclear magnetic resonance (NMR) experiments performed in magnetic fields on the order of microtesla yield line widths comparable to the lifetime limit even in grossly inhomogeneous magnets. The potential loss in sensitivity is overcome by combining prepolarization in fields on the order of millitesla and signal detection with a Superconducting Quantum Interference Device (SQUID). The enhanced spectral resolution attainable in microtesla fields enables NMR studies of pure liquids and solutions without the need for strong magnets. We have investigated a variety of heteronuclear systems in both the weak and strong J-coupling regimes. Six different nuclear species have been detected with the same experimental apparatus. NMR signals of thermally polarized protons were obtained in fields as low as 554 nT.

}, keywords = {water}, isbn = {1089-5639}, doi = {Doi 10.1021/Jp035181g}, url = {://WOS:000188831500005}, author = {Trabesinger, A. H. and McDermott, R. and Lee, S. K. and M{\"u}ck, M. and Clarke, J. and Pines, A.} } @article {332, title = {SQUID-detected magnetic resonance imaging in microtesla magnetic fields}, journal = {Journal of Low Temperature Physics}, volume = {135}, year = {2004}, note = {J Low Temp Phys824TWTimes Cited:37Cited References Count:34}, month = {Jun}, pages = {793-821}, abstract = {

We describe studies of nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI) of liquid samples at room temperature in microtesla magnetic fields. The nuclear spins are prepolarized in a strong transient field. The magnetic signals generated by the precessing spins, which range in frequency from tens of Hz to several kHz, are detected by a low-transition temperature dc SQUID (Superconducting QUantum Interference Device) coupled to an untuned, superconducting flux transformer configured as an axial gradiometer. The combination of prepolarization and frequency-independent detector sensitivity results in a high signal-to-noise ratio and high spectral resolution (similar to 1 Hz) even in grossly inhomogeneous magnetic fields. In the NMR experiments, the high spectral resolution enables us to detect the 10-Hz splitting of the spectrum of protons due to their scalar coupling to a P-31 nucleus. Furthermore, the broadband detection scheme combined with a non-resonant field-reversal spin echo allows the simultaneous observation of signals from protons and P-31 nuclei, even though their NMR resonance frequencies differ by a factor of 2.5. We extend our methodology to MRI in microtesla fields, where the high spectral resolution translates into high spatial resolution. We demonstrate two-dimensional images of a mineral oil phantom and slices of peppers, with a spatial resolution of about 1 mm. We also image an intact pepper using slice selection, again with 1-mm, resolution. A further experiments we demonstrate T-1-contrast imaging of a water phantom, some parts of which were doped with a paramagnetic salt to reduce the longitudinal relaxation time T-1. Possible applications of this MRI technique include screening for tumors and integration with existing multichannel SQUID systems for brain imaging.

}, keywords = {mri}, isbn = {0022-2291}, doi = {Doi 10.1023/B:Jolt.0000029519.09286.C5}, url = {://WOS:000221710600023}, author = {McDermott, R. and Kelso, N. and Lee, S. K. and Mossle, M. and M{\"u}ck, M. and Myers, W. and ten Haken, B. and Seton, H. C. and Trabesinger, A. H. and Pines, A. and Clarke, J.} } @article {336, title = {Three-dimensional phase-encoded chemical shift MRI in the presence of inhomogeneous fields}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {101}, year = {2004}, note = {P Natl Acad Sci USA830EQTimes Cited:18Cited References Count:12}, month = {Jun 15}, pages = {8845-8847}, abstract = {

A pulse sequence consisting of an excitation pulse and two adiabatic full-passage pulses with scaled relative peak amplitudes is combined with phase encoding to recover chemical shift information within 3D images in a 1D inhomogeneous static magnetic field with a matched rf field gradient. The results are discussed in the context of ex situ magnetic resonance and imaging. The future directions of our research in implementing the ex situ technique in a real one-sided system are also discussed.

}, keywords = {pulses}, isbn = {0027-8424}, doi = {Doi 10.1073/Pnas.0403016101}, url = {://WOS:000222104900004}, author = {Demas, V. and Sakellariou, D. and Meriles, C. A. and Han, S. and Reimer, J. and Pines, A.} } @article {329, title = {Variable angle spinning (VAS) NMR study of solvent effects in liquid crystalline solutions of C-13-iodomethane}, journal = {Chemical Physics Letters}, volume = {399}, year = {2004}, note = {Chem Phys Lett874AXTimes Cited:5Cited References Count:28}, month = {Nov 21}, pages = {196-199}, abstract = {

NMR spectra of C-13-iodomethane oriented in three different liquid crystalline solvents have been collected and analyzed under spinning at various angles with respect to the static magnetic field. For each sample the ratio of homonuclear (H-1-H-1) to heteronuclear (C-13-H-1) dipolar couplings, which is a function of the geometry of the solute molecule, does not change significantly with the scaling of the dipolar couplings due to spinning at different angles. This result implies that the \&$\#$39;apparent bond angle deviations\&$\#$39; (Deltatheta(a)), previously calculated from thermotropic liquid crystals, arise from a solvent effect and are not an artifact from scaling the anisotropic interactions. (C) 2004 Elsevier B.V. All rights reserved.

}, keywords = {phases}, isbn = {0009-2614}, doi = {Doi 10.1016/J.Cplett.2004.10.009}, url = {://WOS:000225324400036}, author = {Park, G. H. J. and Martin, R. W. and Sakellariou, D. and Pines, A. and Shahkhatuni, A. G. and Shahkhatuni, A. A. and Panosyan, H. A.} } @article {340, title = {Amplification of xenon NMR and MRI by remote detection}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {100}, year = {2003}, note = {P Natl Acad Sci USA709HPTimes Cited:65Cited References Count:28}, month = {Aug 5}, pages = {9122-9127}, abstract = {

A technique is proposed in which an NMR spectrum or MRI is encoded and stored as spin polarization and is then moved to a different physical location to be detected. Remote detection allows the separate optimization of the encoding and detection steps, permitting the independent choice of experimental conditions and excitation and detection methodologies. In the initial experimental demonstration of this technique, we show that taking dilute Xe-129 from a porous sample placed inside a large encoding coil and concentrating it into a smaller detection coil can amplify NMR signal. In general, the study of NMR active molecules at low concentration that have low physical filling factor is facilitated by remote detection. In the second experimental demonstration, MRI information encoded in a very low-field magnet (4-7 mT) is transferred to a high-field magnet (4.2 T) to be detected under optimized conditions. Furthermore, remote detection allows the utilization of ultrasensitive optical or superconducting quantum interference device detection techniques, which broadens the horizon of NMR experimentation.

}, keywords = {field}, isbn = {0027-8424}, doi = {Doi 10.1073/Pnas.1133497100}, url = {://WOS:000184620000007}, author = {Moule, A. J. and Spence, M. M. and Han, S. I. and Seeley, J. A. and Pierce, K. L. and Saxena, S. and Pines, A.} } @article {343, title = {Applications of Laser-Polarized 129 XE NMR to Biomolecular Assays}, journal = {Magnetic Resonance Imaging}, year = {2003}, pages = {1235-1239}, doi = {10.1016/J.Mri.2003.08.025}, author = {Lowery, T.J. and Rubin, S.M. and Ruiz, E.J. and Spence, M.M. and Winssinger, N. and Schultz, P.G. and Pines, A. and Wemmer, D.E.} } @article {341, title = {Broadband phase modulation by adiabatic pulses}, journal = {Journal of Magnetic Resonance}, volume = {164}, year = {2003}, note = {J Magn Reson717NCTimes Cited:14Cited References Count:14}, month = {Sep}, pages = {177-181}, abstract = {

The use of inhomogeneous but spatially correlated static and radiofrequency (RF) magnetic fields offers a potential methodology for performing magnetic resonance spectroscopy of samples placed outside the bore of the magnet. However, its practical implementation still presents challenging problems, among them the control of nuclear spins over broad frequency offset intervals. The present study introduces an efficient method of encoding the phase of the magnetization when the variation of the static field along the sample is much larger than the RF amplitude. The procedure is based on the use of consecutively applied full-passage adiabatic pulses. The induced phase modulation is broadband and selective because it does not depend on the offset relative to the central frequency and the limits can be sharply defined. Finally, the encoded phase depends almost linearly on the local RF amplitude. All these features enable the recovery of an inhomogeneity-free spectrum with amplitudes close to the theoretically attainable maximum. Published by Elsevier Science (USA).

}, keywords = {fields}, isbn = {1090-7807}, doi = {Doi 10.1016/S1090-7807(03)00157-5}, url = {://WOS:000185095200023}, author = {Meriles, C. A. and Sakellariou, D. and Pines, A.} } @article {339, title = {High-resolution NMR correlation spectra of disordered solids}, journal = {Journal of the American Chemical Society}, volume = {125}, year = {2003}, note = {J Am Chem Soc663JYTimes Cited:70Cited References Count:46}, month = {Apr 9}, pages = {4376-4380}, abstract = {

We show how high-resolution NMR spectra can be obtained for solids for which the spectra are normally broadened due to structural disorder. The method relies on correlations in the chemical shifts between pairs of coupled spins. It is found experimentally that there are strong correlations in the chemical shifts between neighboring spins in both phosphorus-31 and carbon-13 spectra. These correlations can be exploited not only to provide resolution in two-dimensional spectra, but also to yield \"chains\" of correlated chemical shifts, constituting a valuable new source of structural information for disordered materials.

}, keywords = {SPECTROSCOPY}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja0292389}, url = {://WOS:000182003500067}, author = {Sakellariou, D. and Brown, S. P. and Lesage, A. and Hediger, S. and Bardet, M. and Meriles, C. A. and Pines, A. and Emsley, L.} } @article {338, title = {High-resolution NMR of anisotropic samples with spinning away from the magic angle}, journal = {Chemical Physics Letters}, volume = {377}, year = {2003}, note = {Chem Phys Lett714CRTimes Cited:6Cited References Count:27}, month = {Aug 15}, pages = {333-339}, abstract = {

High-resolution NMR of anisotropic samples is typically performed by spinning the sample around an axis at the magic angle of 54.7degrees with the static magnetic field. Geometric and engineering constraints often prevent spinning at this specific angle. Implementations of magic angle field rotation are extremely demanding due to power requirements or an inaccessible geometry. We present a methodology for taking the magic out of MAS while still obtaining both isotropic and anisotropic spectral information during sample spinning or field rotation at arbitrary angles. Using projected-MAS, we obtained resolved scaled isotropic chemical shifts in inhomogeneously broadened spinning samples. Published by Elsevier B.V.

}, keywords = {axis}, isbn = {0009-2614}, doi = {Doi 10.1016/S0009-2614(03)01149-7}, url = {://WOS:000184895200012}, author = {Sakellariou, D. and Meriles, C. A. and Martin, R. W. and Pines, A.} } @article {342, title = {Inclusion complexes oriented in thermotropic liquid-crystalline solvents studied with carbon-13 NMR}, journal = {Journal of Physical Chemistry B}, volume = {107}, year = {2003}, note = {J Phys Chem B743MATimes Cited:11Cited References Count:19}, month = {Nov 20}, pages = {12558-12561}, abstract = {

The inclusion complex of cryptophane-A and chloroform dissolved in two nonchiral liquid-crystalline environments was investigated via C-13 NMR. Stable solutions of oriented complexes were prepared using aromatic (ZLI 1132) and aliphatic (ZLI 1695) thermotropic nematic liquid crystals as solvents; ordering of the complexes was manifested by the H-1-C-13 dipolar splitting of the C-13 resonance of labeled chloroform. In both solutions, the dipolar splitting for the bound ligands was substantially larger than that obtained for the free ligands, indicating a significant increase in ligand ordering upon complexation despite the absence of direct contact with the oriented solvent molecules. A similar enhancement in ordering was observed for complexed ligands compared to that for free ligands in both liquid-crystalline solvents. Also, the application of heteronuclear decoupling to the ZLI 1695 solution resulted in a reduced line width for the bound C-13 chloroform resonance, suggesting that a significant component of the observed line broadening may originate from intermolecular couplings between host and guest molecules. These results demonstrate the potential for using restored dipolar couplings to investigate structural and dynamical aspects of inclusion complexes in solution.

}, keywords = {xe-129}, isbn = {1520-6106}, doi = {Doi 10.1021/Jp030431e}, url = {://WOS:000186574500003}, author = {Marjanska, M. and Goodson, B. M. and Castiglione, F. and Pines, A.} } @article {345, title = {Using switched angle spinning to simplify NMR spectra of strongly oriented samples}, journal = {Journal of the American Chemical Society}, volume = {125}, year = {2003}, note = {J Am Chem Soc695CXTimes Cited:13Cited References Count:38}, month = {Jul 2}, pages = {7998-8006}, abstract = {

This contribution describes a method that manipulates the alignment director of a liquid crystalline sample to obtain anisotropic magnetic interaction parameters, such as dipolar coupling, in an oriented liquid crystalline sample. By changing the axis of rotation with respect to the applied magnetic field in a spinning liquid crystalline sample, the dipolar couplings present in a normally complex strong coupling spectrum are scaled to a simple weak coupling spectrum. This simplified weak coupling spectrum is then correlated with the isotropic chemical shift in a switched angle spinning (SAS) two-dimensional (2D) experiment. This dipolar-isotropic 2D correlation was also observed for the case where the couplings are scaled to a degree where the spectrum approaches strong coupling. The SAS 2D correlation of C6F5Cl in the nematic liquid crystal I52 was obtained by first evolving at an angle close to the magic angle (54.7degrees) and then directly detecting at the magic angle. The SAS method provides a 2D correlation where the weak coupling pairs are revealed as cross-peaks in the indirect dimension separated by the isotropic chemical shifts in the direct dimension. Additionally, by using a more complex SAS method which involves three changes of the spinning axis, the solidlike spinning sideband patterns were correlated with the isotropic chemical shifts in a 2D experiment. These techniques are expected to enhance the interpretation and assignment of an isotropic. magnetic interactions including dipolar couplings for molecules dissolved in oriented liquid crystalline phases.

}, keywords = {solids}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja0342244}, url = {://WOS:000183814500059}, author = {Havlin, R. H. and Park, G. H. J. and Mazur, T. and Pines, A.} } @article {352, title = {Creating isotropic dipolar spectra for a pair of dipole coupled spins in high-field}, journal = {Chemical Physics Letters}, volume = {363}, year = {2002}, note = {Chem Phys Lett595CVTimes Cited:3Cited References Count:20}, month = {Sep 9}, pages = {372-380}, abstract = {

In the absence of a strong magnetic field, the dipolar interaction between two nuclear spins is independent of orientation leading to sharp lines. However, in high magnetic fields the Zeeman interaction breaks the symmetry of space and spin producing an anisotropic dipolar spectra. In the following Letter, a method that yields isotropic dipolar spectra for a pair of dipole-coupled spins is presented. This is accomplished through a suitable choice of coherence pathways and average Hamiltonians. We present a theoretical explanation as well as an experimental verification for this novel methodology. (C) 2002 Elsevier Science B.V. All rights reserved.

}, keywords = {angle}, isbn = {0009-2614}, doi = {Doi 10.1016/S0009-2614(02)01188-0}, url = {://WOS:000178090000027}, author = {Walls, J. D. and Blanton, W. B. and Havlin, R. H. and Pines, A.} } @article {354, title = {Detection and characterization of xenon-binding sites in proteins by Xe-129 NMR spectroscopy}, journal = {Journal of Molecular Biology}, volume = {322}, year = {2002}, note = {J Mol Biol597PTTimes Cited:53Cited References Count:54}, month = {Sep 13}, pages = {425-440}, abstract = {

Xenon-binding sites in proteins have led to a number of applications of xenon in biochemical and structural studies. Here we further develop the utility of Xe-129 NMR in characterizing specific xenon-protein interactions. The sensitivity of the Xe-129 chemical shift to its local environment and the intense signals attainable by optical pumping make xenon a useful NMR reporter of its own interactions with proteins. A method for detecting specific xenon-binding interactions by analysis of Xe-129 chemical shift data is illustrated using the maltose binding protein (MBP) from Escherichia coli as an example. The crystal structure of MBP in the presence of 8 atm of xenon confirms the binding site determined from NMR data. Changes in the structure of the xenon-binding cavity upon the binding of maltose by the protein can account for the sensitivity of the Xe-129 chemical shift to MBP conformation. Xe-129 NMR data for xenon in solution with a number of cavity containing phage T4 lysozyme mutants show that xenon can report on cavity structure. In particular, a correlation exists between cavity size and the binding-induced Xe-129 chemical shift. Further applications of Xe-129 NMR to biochemical assays, including the screening of proteins for xenon binding for crystallography are considered. (C) 2002 Elsevier Science Ltd. All rights reserved

}, keywords = {nonpolar cavity}, isbn = {0022-2836}, doi = {Doi 10.1016/S0022-2836(02)00739-8}, url = {://WOS:000178230500014}, author = {Rubin, S. M. and Lee, S. Y. and Ruiz, E. J. and Pines, A. and Wemmer, D. E.} } @article {361, title = {Efficient triple-quantum excitation in modified RIACT MQMAS NMR for I=3/2 nuclei}, journal = {Journal of Magnetic Resonance}, volume = {154}, year = {2002}, note = {J Magn Reson527MFTimes Cited:15Cited References Count:31}, month = {Feb}, pages = {196-204}, abstract = {

A new approach involving the creation of triple-quantum (TQ) coherences from both TQ and central transitions (CT) is investigated, in order to enhance the efficiency of triple-quantum excitation for I = 3/2 nuclei. The RIACT excitation scheme, a soft pi/2 and hard spin-locking pulse, is shown to induce both adiabatic coherence transfer between CT and TQ coherences and TQ nutation. By combining the RIACT scheme with the presaturation of the satellite transitions, a significant improvement in the TQ excitation can be achieved mainly through enhanced CT polarization via the RIACT mechanism, in particular for nuclei with moderate to large quadrupole coupling constants (greater than or equal to2.0 MHz). There also exists a nontrivial contribution from the TQ transition, which depends on the size of the quadrupole interaction. (C) 2002 Elsevier Science (USA).

}, keywords = {coherence}, isbn = {1090-7807}, doi = {Doi 10.1006/Jmre.2001.2471}, url = {://WOS:000174189300005}, author = {Lim, K. H. and Charpentier, T. and Pines, A.} } @article {359, title = {Investigations of low-amplitude radio frequency pulses at and away from rotary resonance conditions for I=5/2 Nuclei}, journal = {Solid State Nuclear Magnetic Resonance}, volume = {22}, year = {2002}, note = {Solid State Nucl Mag613WLTimes Cited:8Cited References Count:40}, month = {Sep-Nov}, pages = {97-109}, abstract = {

Additional experimental evidence of rotary resonance effects for multiple-quantum coherence conversion in a spin-5/2 system is presented. Two-dimensional plots of the relative efficiency of MQ excitation and conversion are given as a function of radio frequency (rf) amplitude and pulse width. Data are presented for the excitation of five-quantum coherence (5QC), as well as for 5QC to three-quantum coherence (3QC) conversion, 5QC to 1QC (the central transition coherence) conversion, and 3QC to 1 QC conversion. A two-fold increase in the signal-to-noise ratio is achieved by substituting low amplitude rf pulses in place of hard rf pulses for 5QC excitation and 5QC to 3QC conversion in a mixed multiple-quantum magic angle spinning (MAS) (MMQMAS) experiment. The anisotropic line shape for the low-amplitude rf pulse version of the MMQMAS experiment was observed to be distorted from the MAS line shape. The cause and implications of the distortion are discussed. (C) 2002 Elsevier Science (USA).

}, keywords = {solid-state}, isbn = {0926-2040}, doi = {Doi 10.1006/Snmr.2002.0084}, url = {://WOS:000179154400003}, author = {Logan, J. W. and Urban, J. T. and Walls, J. D. and Lim, K. H. and Jerschow, A. and Pines, A.} } @article {346, title = {Laser-polarized Xe-129 NMR and MRI at ultralow magnetic fields}, journal = {Journal of Magnetic Resonance}, volume = {157}, year = {2002}, note = {J Magn Reson600EJTimes Cited:23Cited References Count:25}, month = {Aug}, pages = {235-241}, abstract = {

Laser-polarized Xe-129 and a high-T-c superconducting quantum interference device (SQUID) are used to obtain magnetic resonance images in porous materials at a magnetic field of 2.3 mT, corresponding to a Larmor frequency of 27 kHz. Image resolution of 1 mm is obtained with gradients of only 1 mT/m. The resolution of xenon chemical shifts in different physicochemical environments at ultralow fields is also demonstrated. Details of the circulating flow optical pumping apparatus and the SQUID spectrometer are presented. (C) 2002 Elsevier Science (USA).

}, keywords = {atoms}, isbn = {1090-7807}, doi = {Doi 10.1006/Jmre.2002.2592}, url = {://WOS:000178377400009}, author = {Wong-Foy, A. and Saxena, S. and Moule, A. J. and Bitter, H. M. L. and Seeley, J. A. and McDermott, R. and Clarke, J. and Pines, A.} } @conference {355, title = {"Lighting Up" NMR and MRI in Colloidal and Interfacial Systems}, booktitle = {Magnetic Resonance in Colloid and Interface Sciences}, year = {2002}, month = {2002}, pages = {97-106}, publisher = {Kluwer Academic Publishers, Netherlands}, organization = {Kluwer Academic Publishers, Netherlands}, address = {St. Petersburg, Russia}, author = {Pines, A. and Logan, J.W. and Spence, M. M.}, editor = {J. Fraissard and O. Lapina, eds} } @article {357, title = {Liquid-state NMR and scalar couplings in microtesla magnetic fields}, journal = {Science}, volume = {295}, year = {2002}, note = {Science534ADTimes Cited:140Cited References Count:20}, month = {Mar 22}, pages = {2247-2249}, abstract = {

We obtained nuclear magnetic resonance (NMR) spectra of liquids in fields of a few microtesla, using prepolarization in fields of a few millitesta and detection with a dc superconducting quantum interference device (SQUID). Because the sensitivity of the SQUID is frequency independent, we enhanced both signal-to-noise ratio and spectral resolution by detecting the NMR signal in extremely tow magnetic fields, where the NMR tines become very narrow even for grossly inhomogeneous measurement fields. In the absence of chemical shifts, proton-phosphorous scalar (J) couplings have been detected, indicating the presence of specific covalent bonds. This observation opens the possibility for \"pure J spectroscopy\" as a diagnostic tool, for the detection of molecules in low magnetic fields.

}, keywords = {resonance}, isbn = {0036-8075}, doi = {Doi 10.1126/Science.1069280}, url = {://WOS:000174561700039}, author = {McDermott, R. and Trabesinger, A. H. and M{\"u}ck, M. and Hahn, E. L. and Pines, A. and Clarke, J.} } @article {358, title = {Measurement of dipolar couplings in partially oriented molecules by local field NMR spectroscopy with low-power decoupling}, journal = {Journal of Magnetic Resonance}, volume = {158}, year = {2002}, note = {J Magn Reson619VETimes Cited:8Cited References Count:23}, month = {Sep-Oct}, pages = {52-59}, abstract = {

Low-power phase-modulated Lee-Goldburg homonuclear decoupling was used to record PDLF spectra of fluorine-substituted benzene derivatives dissolved in nematic thermotropic liquid crystalline solvents. The low-power decoupling minimizes sample heating during RE irradiation while still achieving highly resolved PDLF spectra. The method is illustrated by recording spectra for 1,3-dichloro-4-fluoro-5-nitrobenzene, 1,3-dichloro-4-fluorobenzene, and 1, 2-difluoro benzene dissolved in different nematic solvents. (C) 2002 Elsevier Science (USA). All rights reserved.

}, keywords = {resolution}, isbn = {1090-7807}, doi = {Doi 10.1016/S1090-7807(02)00059-9}, url = {://WOS:000179497500006}, author = {Marjanska, M. and Castiglione, F. and Walls, J. D. and Pines, A.} } @article {348, title = {Reintroducing anisotropic interactions in magic-angle-spinning NMR of half-integer quadrupolar nuclei: 3D MQMAS}, journal = {Journal of the American Chemical Society}, volume = {124}, year = {2002}, note = {J Am Chem Soc591GWTimes Cited:14Cited References Count:21}, month = {Sep 11}, pages = {10652-10653}, keywords = {redor}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja027043v}, url = {://WOS:000177872200011}, author = {Wi, S. and Heise, H. and Pines, A.} } @article {356, title = {Resolved magic-angle spinning of anisotropic samples in inhomogeneous fields}, journal = {Chemical Physics Letters}, volume = {358}, year = {2002}, note = {Chem Phys Lett565JGTimes Cited:10Cited References Count:14}, month = {Jun 7}, pages = {391-395}, abstract = {

The chemical shift spectrum of a liquid embedded in a porous sample spinning at the magic angle has been recovered in the presence of static field and rf gradients. Field inhomogeneity and susceptibility broadening are averaged by a procedure that combines magic-angle turning with a train of z-rotation pulses. The experiment emulates the situation encountered in \&$\#$39;ex situ\&$\#$39; NMR in which the sample is located away from the field sources. Given the equivalence of field and sample spinning, the results suggest that the use of a rotating magnetic field and refocusing pulses might enable the study of samples such as solids or fluids in porous materials external to the magnet. (C) 2002 Elsevier Science B.V. All rights reserved.

}, keywords = {pulses}, isbn = {0009-2614}, doi = {Doi 10.1016/S0009-2614(02)00642-5}, url = {://WOS:000176365900005}, author = {Meriles, C. A. and Sakellariou, D. and Pines, A.} } @article {347, title = {Rotary resonance recoupling for half-integer quadrupolar nuclei in solid-state nuclear magnetic resonance spectroscopy}, journal = {Journal of Chemical Physics}, volume = {117}, year = {2002}, note = {J Chem Phys599CVTimes Cited:22Cited References Count:53}, month = {Oct 15}, pages = {7024-7033}, abstract = {

Investigations were made of rotary resonance recouplings (R-3) of chemical shift anisotropy (CSA), heteronuclear dipolar (HTD), and homonuclear dipolar (HMD) couplings involving half-integer quadrupolar nuclei under magic-angle sample spinning condition. Under rotary resonance conditions provided by a low amplitude rf field and a high spinning speed, the spectrum of the central transition coherence of half-integer quadrupolar nuclei shows recouplings of CSA, HTD, and HMD interactions that depend on the ratio of the rf field to the spinning speed. These new properties can be used to extract electronic and structural information about the sample that are otherwise difficult to extract in the presence of a dominant quadrupolar interaction. An average Hamiltonian theory is used to explain the recoupling properties of various interactions. Experimental implementations of the R-3 are demonstrated on model compounds with spin-3/2 systems. (C) 2002 American Institute of Physics.

}, keywords = {polarization}, isbn = {0021-9606}, doi = {Doi 10.1063/1.1506907}, url = {://WOS:000178317300016}, author = {Wi, S. and Logan, J. W. and Sakellariou, D. and Walls, J. D. and Pines, A.} } @article {349, title = {Selective excitation in dipole coupled systems}, journal = {Chemical Physics Letters}, volume = {357}, year = {2002}, note = {Chem Phys Lett558GVTimes Cited:5Cited References Count:22}, month = {May 10}, pages = {241-248}, abstract = {

In this Letter the possibility of selective excitation in coupled multispin systems is studied theoretically. A general method of transforming any selective pulse developed for uncoupled systems into a form that is selective in coupled systems is presented. This is accomplished by adding a small perturbation to a decoupling radiofrequency (RF) field. When viewed in an interaction frame given by the decoupling RF field, this method generates, in an averaged sense, a propagator similar to the propagator of uncoupled spins under a shaped RF pulse. Preliminary experimental results are presented for the case of selective excitation in proton nuclear magnetic resonance in liquid crystals. (C) 2002 Elsevier Science B.V. All rights reserved.

}, keywords = {spin-diffusion}, isbn = {0009-2614}, doi = {Doi 10.1016/S0009-2614(02)00493-1}, url = {://WOS:000175958700012}, author = {Walls, J. D. and Marjanska, M. and Sakellariou, D. and Castiglione, F. and Pines, A.} } @article {360, title = {Sensitivity enhancement in multiple-quantum NMR experiments with CPMG detection}, journal = {Journal of Magnetic Resonance}, volume = {157}, year = {2002}, note = {J Magn Reson589DHTimes Cited:12Cited References Count:12}, month = {Jul}, pages = {160-162}, abstract = {

We present a modified multiple-quantum (MQ) experiment, which implements the Carr-Purcell-Meiboom-Gill (CPMG) detection scheme in the static MQ NMR experiment proposed by W. S. Warren et al. (1980, J. Chem. Phys. 73, 2084-2099) and exploited further by O. N. Antzutkin and R. Tycko (1999, J. Chem. Phys. 110, 2749-2752). It is demonstrated that a significant enhancement in the sensitivity can be achieved by acquiring echo trains in the MQ experiments for static powder samples. The modified scheme employing the CPMG detection was superior to the original MQ experiment, in particular for the carbonyl carbon with a very large chemical shift anisotropy. (C) 2002 Elsevier Science (USA).

}, keywords = {dynamics}, isbn = {1090-7807}, doi = {Doi 10.1006/Jmre.2002.2578}, url = {://WOS:000177742400019}, author = {Lim, K. H. and Nguyen, T. and Mazur, T. and Wemmer, D. E. and Pines, A.} } @article {351, title = {Theoretical investigations of I=5/2 quadrupolar spin dynamics in the sudden-passage regime}, journal = {Journal of Chemical Physics}, volume = {117}, year = {2002}, note = {J Chem Phys566JRTimes Cited:3Cited References Count:44}, month = {Jul 8}, pages = {518-532}, abstract = {

The theoretical approach utilizing bimodal Floquet theory in the quadrupolar/central-transition interaction frame, presented in an earlier article [J. D. Walls, K. H. Lim, and A. Pines, J. Chem. Phys. 116, 79 (2002)], is extended to describe the more complicated spin dynamics of I=5/2 spin systems. Rotary resonance effects occur when the strength of the radio-frequency irradiation, omega(1), matches the sample spinning speed, omega(r), at the conditions omega(1) = 2/3nomega(r) (n integral). At these conditions, conversions of both triple-quantum and five-quantum coherences to central-quantum coherence are observed. Between rotary resonance conditions [ 2n/3omega(r)\<ω(1)\<[2(n+1)]/3ω(r)], five-quantum as well as triple-quantum coherences can be created from equilibrium z-magnetization via a nutation mechanism. In addition, effective transfer between five-quantum and triple-quantum coherences also is observed in between rotary resonance conditions. These effects have been investigated theoretically and verified by both numerical calculations and experimental results. (C) 2002 American Institute of Physics.

}, keywords = {SPECTROSCOPY}, isbn = {0021-9606}, doi = {Doi 10.1063/1.1483256}, url = {://WOS:000176424800003}, author = {Walls, J. D. and Lim, K. H. and Logan, J. W. and Urban, J. T. and Jerschow, A. and Pines, A.} } @article {350, title = {Theoretical studies of the spin dynamics of quadrupolar nuclei at rotational resonance conditions}, journal = {Journal of Chemical Physics}, volume = {116}, year = {2002}, note = {J Chem Phys503ECTimes Cited:12Cited References Count:20}, month = {Jan 1}, pages = {79-90}, abstract = {

A theory of the spin dynamics of I=3/2 quadrupolar nuclei in the sudden-passage limit is discussed in relation to the recently observed rotational resonance (RR) effects on the excitation and conversion of triple-quantum coherence in the FASTER multiple-quantum magic-angle spinning (MQMAS) experiments [T. Vosegaard, P. Florian, D. Massiot, and P. J. Grandinetti, J. Chem. Phys. 114, 4618 (2001)]. A novel interaction frame, which combines the quadrupolar interaction with the central transition radio frequency irradiation, is shown to be useful in understanding the complex spin dynamics at and away from RR conditions. Analytical expressions for the Hamiltonian obtained from bimodal Floquet theory are included in order to provide insight into the spin dynamics observed in the FASTER MQMAS experiments. Numerical simulations have been performed and were found to support the theoretical formalism. (C) 2002 American Institute of Physics.

}, keywords = {solids}, isbn = {0021-9606}, doi = {Doi 10.1063/1.1421613}, url = {://WOS:000172784700010}, author = {Walls, J. D. and Lim, K. H. and Pines, A.} } @article {362, title = {Two-dimensional high-resolution NMR spectra in matched B-0 and B-1 field gradients}, journal = {Journal of Magnetic Resonance}, volume = {156}, year = {2002}, note = {J Magn Reson568UETimes Cited:15Cited References Count:26}, month = {May}, pages = {146-151}, abstract = {

In a recent publication we presented a method to obtain highly resolved NMR spectra in the presence of an inhomogeneous B-0 field with the help of a matched RF gradient. If RF gradient pulses are combined with \"ideal\" 90degrees pulses to form inhomogeneous z rotation pulses, the line broadening caused by the B-0 gradient can be refocused, while the full chemical shift information is maintained. This approach is of potential use for NMR spectroscopy in an inhomogeneous magnetic field produced by an \"ex-situ\" surface spectrometer. In this contribution, we extend this method toward two-dimensional spectroscopy with high resolution in one or both dimensions. Line narrowing in the indirect dimension can be achieved by two types of nutation echoes, thus leading to depth-sensitive NMR spectra with full chemical shift information. If the nutation echo in the indirect dimension is combined with a stroboscopic acquisition using inhomogeneous z-rotation pulses, highly resolved two-dimensional correlation spectra can be obtained in matched field gradients. Finally, we demonstrate that an INEPT coherence transfer from proton to carbon spins is possible in inhomogeneous B-0 fields. Thus, it is possible to obtain one-dimensional C-13 NMR spectra with increased sensitivity and two-dimensional HETCOR spectra in the presence of B-0 gradients of 0.4 mT/cm. These schemes may be of some value for ex-situ NMR analysis of materials and biological systems. (C) 2002 Elsevier Science (USA).

}, keywords = {echoes}, isbn = {1090-7807}, doi = {Doi 10.1006/Jmre.2002.2545}, url = {://WOS:000176562100016}, author = {Heise, H. and Sakellariou, D. and Meriles, C. A. and Moule, A. and Pines, A.} } @article {363, title = {Two-dimensional NMR correlations of liquid crystals using switched angle spinning}, journal = {Journal of Magnetic Resonance}, volume = {157}, year = {2002}, note = {J Magn Reson589DHTimes Cited:10Cited References Count:28}, month = {Jul}, pages = {163-169}, abstract = {

We present the first application of switched angle spinning (SAS) to correlate the first-order dipolar spectrum of a liquid crystalline sample with the isotropic magic angle spinning (MAS) spectrum in a two-dimensional experiment. In this experiment we are able to select the degree of dipolar couplings introduced via mechanical manipulations of the liquid crystal director in a single oriented sample. The F-19 SAS-COSY correlation of iodotrifluoroethylene, an AMX spin system, dissolved in the nematic liquid crystal 4-octylphenyl-2-chloro-4-(4-heptylbenzoyloxy)-benzoate provides assignment of both the J and dipolar couplings in a single experiment. This work demonstrates the use of oriented samples and sample spinning to resolve hornonuclear dipolar couplings using isotropic chemical shifts. (C) 2002 Elsevier Science (USA).

}, keywords = {dynamics}, isbn = {1090-7807}, doi = {Doi 10.1006/Jmre.2002.2571}, url = {://WOS:000177742400020}, author = {Havlin, R. H. and Park, G. H. J. and Pines, A.} } @article {353, title = {Variable rotation composite pulses for high resolution nuclear magnetic resonance using inhomogeneous magnetic and radiofrequency fields}, journal = {Chemical Physics Letters}, volume = {363}, year = {2002}, note = {Chem Phys Lett591TPTimes Cited:17Cited References Count:23}, month = {Sep 2}, pages = {25-33}, abstract = {

An approach toward high-resolution NMR spectroscopy on samples located outside the physical confines of a magnet (ex situ NMR), has recently been described [C.A. Meriles, D. Sakellariou, H. Heise, A.J. Moule, A. Pines, Science 293 (2001) 82]. Nutation echoes are generated by a train of z-rotation pulses in the presence of spatially matched static and rf field gradients. These pulses were based on a combination of \&$\#$39;perfect\&$\#$39; pi/2 constant rotation composite pulses and \&$\#$39;imperfect\&$\#$39; ordinary pulses of variable length. Here we introduce a new class of \&$\#$39;self-compensated\&$\#$39; z-rotation composite pulses based only on variable rotation inversion pulses that lead to an rf dependent phase shift. Experiments and simulations show that these new pulses perform well at high B-0 gradients and require less rf power than previous schemes. (C) 2002 Elsevier Science B.V. All rights reserved.

}, keywords = {echoes}, isbn = {0009-2614}, doi = {Doi 10.1016/S0009-2614(02)01116-8}, url = {://WOS:000177896600005}, author = {Sakellariou, D. and Meriles, C. A. and Moule, A. and Pines, A.} } @article {369, title = {Approach to high-resolution ex situ NMR spectroscopy}, journal = {Science}, volume = {293}, year = {2001}, note = {Science451BBTimes Cited:109Cited References Count:20}, month = {Jul 6}, pages = {82-85}, abstract = {

Nuclear magnetic resonance (NMR) experiments are typically performed with samples immersed in a magnet shimmed to high homogeneity. However, there are many circumstances in which it is impractical or undesirable to insert objects or subjects into the bore of a high-field magnet. Here we present a methodology based on an adaptation of nutation echoes that provides resolved spectra in the presence of matched inhomogeneous static and radiofrequency fields, thereby opening the way to high-resolution exsitu NMR, The observation of chemical shifts is regained through the use of multiple-pulse sequences of correlated, composite z-rotation pulses, producing resolved NMR spectra of liquid samples.

}, keywords = {echoes}, isbn = {0036-8075}, doi = {Doi 10.1126/Science.1061498}, url = {://WOS:000169780300032}, author = {Meriles, C. A. and Sakellariou, D. and Heise, H. and Moule, A. J. and Pines, A.} } @article {366, title = {Characterization of the effects of nonspecific xenon-protein interactions on Xe-129 chemical shifts in aqueous solution: Further development of xenon as a biomolecular probe}, journal = {Journal of Magnetic Resonance}, volume = {152}, year = {2001}, note = {J Magn Reson472QDTimes Cited:37Cited References Count:34}, month = {Sep}, pages = {79-86}, abstract = {

The sensitivity of Xe-129 chemical shifts to weak nonspecific xenon-protein interactions has suggested the use of xenon to probe biomolecular structure and interactions. The realization of this potential necessitates a further understanding of how different macromolecular properties influence the Xe-129 chemical shift in aqueous solution. Toward this goal, we have acquired Xe-129 NMR spectra of xenon dissolved in amino acid, peptide, and protein solutions under both native and denaturing conditions. In general, these cosolutes induce Xe-129 chemical shifts that are downfield relative to the shift in water, as they deshield the xenon nucleus through weak, diffusion-mediated interactions. Correlations between the extent of deshielding and molecular properties including chemical identity, structure, and charge are reported. Xenon deshielding was found to depend linearly on protein size under denaturing solution conditions; the denaturant itself has a characteristic effect on the Xe-129 chemical shift that likely results from a change in the xenon solvation shell structure. In native protein solutions, contributions to the overall Xe-129 chemical shift arise from the presence of weak xenon binding either in cavities or at the protein surface. Potential applications of xenon as a probe of biological systems including the detection of conformational changes and the possible quantification of buried surface area at protein-protein interfaces are discussed. (C) 2001 Academic Press.

}, keywords = {gas}, isbn = {1090-7807}, doi = {Doi 10.1006/Jmre.2001.2389}, url = {://WOS:000170995700009}, author = {Rubin, S. M. and Spence, M. M. and Pines, A. and Wemmer, D. E.} } @article {367, title = {Detection of a conformational change in maltose binding protein by Xe-129 NMR spectroscopy}, journal = {Journal of the American Chemical Society}, volume = {123}, year = {2001}, note = {J Am Chem Soc467XNTimes Cited:28Cited References Count:28}, month = {Sep 5}, pages = {8616-8617}, keywords = {blood}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja0110325}, url = {://WOS:000170729200029}, author = {Rubin, S. M. and Spence, M. M. and Dimitrov, I. E. and Ruiz, E. J. and Pines, A. and Wemmer, D. E.} } @article {371, title = {Dynamic NMR microscopy of gas phase Poiseuille flow}, journal = {Journal of Magnetic Resonance}, volume = {149}, year = {2001}, note = {J Magn Reson421TCTimes Cited:17Cited References Count:16}, month = {Mar}, pages = {144-148}, abstract = {

Dynamic NMR microscopy has been used to study xenon gas undergoing Poiseuille flow in the regime where deterministic and stochastic motions are the same order of magnitude. For short observation time, the flow profile images are largely influenced by the longitudinal diffusion, manifested by large displacements in both positive and negative directions. For longer observation time, the effect of the mixing between the fast and slow flow components due to transverse diffusion becomes apparent. A spin-echo version of the dynamic NMR experiment yields images exhibiting strong distortions for longer observation time due to fast diffusion under the \"natural\" gradient from magnetic field inhomogeneity (compared to results obtained with a stimulated echo version). This effect is used as an edge-enhancement filter by employing a longer time duration of the imaging gradient in a stimulated echo experiment. (C) 2001 Academic Press.

}, keywords = {transport}, isbn = {1090-7807}, doi = {Doi 10.1006/Jmre.2000.2283}, url = {://WOS:000168078800021}, author = {Kaiser, L. G. and Logan, J. W. and Meersmann, T. and Pines, A.} } @article {373, title = {An experimental and theoretical investigation of the chemical shielding tensors of C-13(alpha) of alanine, valine, and leucine residues in solid peptides and in proteins in solution}, journal = {Journal of the American Chemical Society}, volume = {123}, year = {2001}, note = {J Am Chem Soc486FTTimes Cited:47Cited References Count:31}, month = {Oct 24}, pages = {10362-10369}, abstract = {

We have carried out a solid-state magic-angle sample-spinning (MAS) nuclear magnetic resonance (NMR) spectroscopic investigation of the C-13(alpha), chemical shielding tensors of alanine, valine, and leucine residues in a series of crystalline peptides of known structure. For alanine and leucine, which are not branched at the beta -carbon, the experimental chemical shift anisotropy (CSA) spans (Omega) are large, about 30 ppm, independent of whether the residues adopt helical or sheet geometries, and are in generally good accord with Omega values calculated by using ab initio Hartree-Fock quantum chemical methods. The experimental Omegas for valine C-alpha in two peptides (in sheet geometries) are also large and in good agreement with theoretical predictions. In contrast, the \"CSAs\" (Delta sigma*) obtained from solution NMR data for alanine, valine, and leucine residues in proteins show major differences, with helical residues having Delta sigma* values of similar to6 ppm while sheet residues have Delta sigma* approximate to 27 ppm. The origins of these differences are shown to be due to the different definitions of the CSA, When defined in terms of the solution NMR CSA, the solid-state results also show small helical but large sheet CSA values. These results are of interest since they lead to the idea that only the beta -branched amino acids threonine, valine, and isoleucine can have small (static) tensor spans, Omega (in helical creometries), and that the small helical \"CSAs\" seen in solution NMR are overwhelmingly dominated by changes in tensor orientation, from sheet to helix. These results have important implications for solid-state NMR structural studies which utilize the CSA span, Omega, to differentiate between helical and sheet residues. Specifically, there will be only a small degree of spectral editing possible in solid proteins since the spans, Omega, for the dominant nonbranched amino acids are quite similar. Editing on the basis of Omega will, however, be very effective for many Thr, Val, and Hen residues, which frequently have small (similar to 15-20 ppm) helical CSA (Omega) spans.

}, keywords = {threonine}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja0115060}, url = {://WOS:000171808300025}, author = {Havlin, R. H. and Laws, D. D. and Bitter, H. M. L. and Sanders, L. K. and Sun, H. H. and Grimley, J. S. and Wemmer, D. E. and Pines, A. and Oldfield, E.} } @article {364, title = {Functionalized xenon as a biosensor}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {98}, year = {2001}, note = {P Natl Acad Sci USA472CZTimes Cited:112Cited References Count:29}, month = {Sep 11}, pages = {10654-10657}, abstract = {

The detection of biological molecules and their interactions is a significant component of modern biomedical research. In current biosensor technologies, simultaneous detection is limited to a small number of analytes by the spectral overlap of their signals. We have developed an NMR-based xenon biosensor that capitalizes on the enhanced signal-to-noise, spectral simplicity, and chemical-shift sensitivity of laser-polarized xenon to detect specific biomolecules at the level of tens of nanomoles. We present results using xenon \"functionalized\" by a biotin-modified supramolecular cage to detect biotin-avidin binding. This biosensor methodology can be extended to a multiplexing assay for multiple analytes.

}, keywords = {mri}, isbn = {0027-8424}, doi = {Doi 10.1073/Pnas.191368398}, url = {://WOS:000170966800030}, author = {Spence, M. M. and Rubin, S. M. and Dimitrov, I. E. and Ruiz, E. J. and Wemmer, D. E. and Pines, A. and Yao, S. Q. and Tian, F. and Schultz, P. G.} } @article {372, title = {High-resolution NMR of quadrupolar nuclei using mixed multiple-quantum coherences}, journal = {Journal of Magnetic Resonance}, volume = {149}, year = {2001}, note = {J Magn Reson431JNTimes Cited:17Cited References Count:16}, month = {Apr}, pages = {268-270}, abstract = {

A multiple-quantum magic angle spinning (MQMAS) NMR experiment of quadrupolar nuclei is demonstrated, which uses two different multiple quantum coherences in tl to refocus the quadrupolar broadening. This experiment has the potential of achieving improved resolution over current techniques. (C) 2001 Academic Press.

}, keywords = {pulses}, isbn = {1090-7807}, doi = {Doi 10.1006/Jmre.2001.2303}, url = {://WOS:000168628200013}, author = {Jerschow, A. and Logan, J. W. and Pines, A.} } @article {365, title = {Resolution of Xe-129 chemical shifts at ultralow magnetic field}, journal = {Journal of the American Chemical Society}, volume = {123}, year = {2001}, note = {J Am Chem Soc463TWTimes Cited:9Cited References Count:39}, month = {Aug 22}, pages = {8133-8134}, keywords = {adsorption}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja011064s}, url = {://WOS:000170494200027}, author = {Saxena, S. and Wong-Foy, A. and Moule, A. J. and Seeley, J. A. and McDermott, R. and Clarke, J. and Pines, A.} } @article {368, title = {"Shining Light" on NMR and MRI in porous materials}, journal = {Magnetic Resonance Imaging}, volume = {19}, year = {2001}, note = {Magn Reson Imaging455YUTimes Cited:1Cited References Count:0}, month = {Apr-May}, pages = {307-309}, isbn = {0730-725X}, doi = {Doi 10.1016/S0730-725x(01)00241-7}, url = {://WOS:000170056000005}, author = {Pines, A.} } @article {370, title = {Solid-state NMR studies of the secondary structure of a mutant prion protein fragment of 55 residues that induces neurodegeneration}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {98}, year = {2001}, note = {P Natl Acad Sci USA476PCTimes Cited:51Cited References Count:26}, month = {Sep 25}, pages = {11686-11690}, abstract = {

The secondary structure of a 55-residue fragment of the mouse prion protein, MoPrP(89-143), was studied in randomly aggregated (dried from water) and fibrillar (precipitated from water/ acetonitrile) forms by C-13 solid-state NMR. Recent studies have shown that the fibrillar form of the P101L mutant of MoPrP(89-143) is capable of inducing prion disease in transgenic mice, whereas unaggregated or randomly aggregated samples do not provoke disease. Through analysis of C-13 chemical shifts, we have determined that both wild-type and mutant sequence MoPrP(89-143) form a mixture of beta -sheet and alpha -helical conformations in the randomly aggregated state although the beta -sheet content in MoPrP(89-143, P101L) is significantly higher than in the wild-type peptide. In a fibrillar state, MoPrP(89-143, P101L) is completely converted into beta -sheet, suggesting that the formation of a specific beta -sheet structure may be required for the peptide to induce disease. Studies of an analogous peptide from Syrian hamster PrP verify that sequence alterations in residues 101-117 affect the conformation of aggregated forms of the peptides.

}, keywords = {diseases}, isbn = {0027-8424}, doi = {Doi 10.1073/Pnas.201404298}, url = {://WOS:000171237100125}, author = {Laws, D. D. and Bitter, H. M. L. and Liu, K. and Ball, H. L. and Kaneko, K. and Wille, H. and Cohen, F. E. and Prusiner, S. B. and Pines, A. and Wemmer, D. E.} } @article {377, title = {ChemQuizzes for Introductory Chemistry Instruction}, year = {2000}, publisher = {Norton Publishing}, type = {CD}, address = {New York}, author = {Laws, D. and Pines, A.} } @article {375, title = {Evidence of nonspecific surface interactions between laser-polarized xenon and myoglobin in solution}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {97}, year = {2000}, note = {P Natl Acad Sci USA345XMTimes Cited:40Cited References Count:35}, month = {Aug 15}, pages = {9472-9475}, abstract = {

The high sensitivity of the magnetic resonance properties of xenon to its local chemical environment and the large Xe-129 NMR signals attainable through optical pumping have motivated the use of xenon as a probe of macromolecular structure and dynamics. In the present work, we report evidence for nonspecific interactions between xenon and the exterior of myoglobin in aqueous solution, in addition to a previously reported internal binding interaction. Xe-129 chemical shift measurements in denatured myoglobin solutions and under native conditions with varying xenon concentrations confirm the presence of nonspecific interactions. Titration data are modeled quantitatively with treatment of the nonspecific interactions as weak binding sites. Using laser-polarized xenon to measure Xe-129 spin-lattice relaxation times (T-1), we observed a shorter T-1 in the presence of 1 mM denatured apomyoglobin in 6 M deuterated urea (T-1 = 59 +/- 1 s) compared with that in 6 M deuterated urea alone (T-1 = 291 +/- 2 s), suggesting that nonspecific xenon-protein interactions can enhance Xe-129 relaxation. An even shorter T1 was measured in ? mM apomyoglobin in D2O (T-1 = 15 +/- 0.3 s), compared with that in D2O alone (T-1 = 506 +/- 5 s). This difference in relaxation efficiency likely results from couplings between laser-polarized xenon and protons in the binding cavity of apomyoglobin that may permit the transfer of polarization between these nuclei via the nuclear Overhauser effect.

}, keywords = {binding}, isbn = {0027-8424}, doi = {Doi 10.1073/Pnas.170278897}, url = {://WOS:000088840500026}, author = {Rubin, S. M. and Spence, M. M. and Goodson, B. M. and Wemmer, D. E. and Pines, A.} } @article {376, title = {Exploring single-file diffusion in one-dimensional nanochannels by laser-polarized Xe-129 NMR spectroscopy (Cover Article)}, journal = {Journal of Physical Chemistry A}, volume = {104}, year = {2000}, note = {J Phys Chem A383EFTimes Cited:75Cited References Count:22}, month = {Dec 21}, pages = {11665-11670}, abstract = {

Single-file diffusion behavior is expected for atoms and molecules in one-dimensional gas phases of nanochannels with transverse dimensions that do not allow for the particles to bypass each other. Although single-file diffusion may play an important role in a wide range of industrial catalytic, geologic, and biological processes, experimental evidence is scarce despite the fact that the dynamics differ substantially from ordinary diffusion. We demonstrate the application of continuous-flow laser-polarized Xe-129 NMR spectroscopy for the study of gas transport into the effectively one-dimensional channels of a microporous material. The novel methodology makes it possible to monitor diffusion over a time scale of tens of seconds, often inaccessible by conventional NMR experiments. The technique can also be applied to systems with very small mobility factors or diffusion constants that are difficult to determine by currently available methods for diffusion measurement. Experiments using xenon in nanochannel systems can distinguish between unidirectional diffusion and single-file diffusion. The experimental observations indicate that single-file behavior for xenon in an organic nanochannel is persistent even at long diffusion times of over tens of seconds. Finally;using continuous flow laser-polarized Xe-129 NMR spectroscopy, we describe an intriguing correlation between the observed NMR line shape of xenon within the nanochannels and the gas transport into these channels.

}, keywords = {model}, isbn = {1089-5639}, doi = {Doi 10.1021/Jp002322v}, url = {://WOS:000165869600001}, author = {Meersmann, T. and Logan, J. W. and Simonutti, R. and Caldarelli, S. and Comotti, A. and Sozzani, P. and Kaiser, L. G. and Pines, A.} } @article {374, title = {A porous crystalline molecular solid explored by hyperpolarized xenon}, journal = {Angewandte Chemie-International Edition}, volume = {39}, year = {2000}, note = {Angew Chem Int Edit343KUTimes Cited:116Cited References Count:38}, pages = {2695-2698}, keywords = {c-13}, isbn = {1433-7851}, doi = {Doi 10.1002/1521-3773(20000804)39:15<2695::Aid-Anie2695>3.0.Co;2-M}, url = {://WOS:000088702200008}, author = {Sozzani, P. and Comotti, A. and Simonutti, R. and Meersmann, T. and Logan, J. W. and Pines, A.} } @article {378, title = {Visualization of gas flow and diffusion in porous media}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {97}, year = {2000}, note = {P Natl Acad Sci USA294ZRTimes Cited:29Cited References Count:18}, month = {Mar 14}, pages = {2414-2418}, abstract = {

The transport of gases in porous materials is a crucial component of many important processes in science and technology. In the present work, we demonstrate how magnetic resonance microscopy with continuous flow laser-polarized noble gases makes it possible to \"light up\" and thereby visualize, with unprecedented sensitivity and resolution, the dynamics of gases in samples of silica aerogels and zeolite molecular sieve particles. The \"polarization-weighted\" images of gas transport in aerogel fragments are correlated to the diffusion coefficient of xenon obtained from NMR pulsed-field gradient experiments. The technique provides a unique means of studying the combined effects of flow and diffusion in systems with macroscopic dimensions and microscopic internal pore structure.

}, keywords = {xenon}, isbn = {0027-8424}, doi = {Doi 10.1073/Pnas.050012497}, url = {://WOS:000085941400005}, author = {Kaiser, L. G. and Meersmann, T. and Logan, J. W. and Pines, A.} } @proceedings {389, title = {Enhanced Surface NMR of Zeolites and Related Material Using Laser-Polarized Xenon}, journal = {Proc. 12th Int. Zeolite Conf.}, year = {1999}, pages = {2943-2950}, author = {Brunner, E. and Haake, M. and Pines, A. and Reimer, J. and Seydoux, R.} } @article {390, title = {Gas flow MRI using circulating laser-polarized Xe-129}, journal = {Journal of Magnetic Resonance}, volume = {138}, year = {1999}, note = {J Magn Reson196HXTimes Cited:35Cited References Count:15}, month = {May}, pages = {155-159}, abstract = {

We describe an experimental approach that combines multidimensional NMR experiments with a steadily renewed source of laser-polarized Xe-129. Using a continuous flow system to circulate the gas mixture, gas phase NMR signals of laser-polarized Xe-129 can be observed with an enhancement of three to four orders of magnitude compared to the equilibrium Xe-129 NMR signal. Due to the fact that the gas flow recovers the nonequilibrium Xe-129 nuclear spin polarization in 0.2 to 4 s, signal accumulation on the time scale of seconds is feasible, allowing previously inaccessible phase cycling and signal manipulation. Several possible applications of MRI of laser-polarized Xe-129 under continuous flow conditions are presented here. The spin density images of capillary tubes demonstrate the feasibility of imaging under continuous how. Dynamic displacement profiles, measured by a pulsed gradient spin echo experiment, show entry flow properties of the gas passing through a constriction under laminar flow conditions. Further, dynamic displacement profiles of Xe-129, flowing through polyurethane foams with different densities and pore sizes, are presented. (C) 1999 Academic Press.

}, keywords = {xenon}, isbn = {1090-7807}, doi = {Doi 10.1006/Jmre.1998.1675}, url = {://WOS:000080303900021}, author = {Brunner, E. and Haake, M. and Kaiser, L. and Pines, A. and Reimer, J. A.} } @article {382, title = {High-T-c SQUIDs for low-field NMR and MRI of room temperature samples}, journal = {Ieee Transactions on Applied Superconductivity}, volume = {9}, year = {1999}, note = {Ieee T Appl SuperconPart 3225MCTimes Cited:5Cited References Count:18}, month = {Jun}, pages = {4424-4427}, abstract = {

We have constructed a high-T-c SQUID spectrometer to detect NMR signals from samples at room temperature in magnetic fields up to 3 mT. The multiloop SQUID magnetometer has a system noise of about 30 fT/Hz(1/2) at the relevant frequencies of 2 to 100 kHz, The magnetometer is operated in vacuum at 77 K, and is separated from the sample, which is less than 1.5 mm away, by a sapphire window, In a magnetic field of 2 mT we can detect the proton spin echo at 86 kHz without signal averaging. This sensitivity enables us to obtain one-dimensional images. In addition, we present data on hyperpolarized Xe-129, which has an optically pumped polarization of several percent.

}, keywords = {frequencies}, isbn = {1051-8223}, doi = {Doi 10.1109/77.784006}, url = {://WOS:000081964500386}, author = {Schlenga, K. and McDermott, R. F. and Clarke, J. and de Souza, R. E. and Wong-Foy, A. and Pines, A.} } @article {383, title = {Low-field magnetic resonance imaging with a high-T-c dc superconducting quantum interference device}, journal = {Applied Physics Letters}, volume = {75}, year = {1999}, note = {Appl Phys Lett259URTimes Cited:49Cited References Count:19}, month = {Dec 6}, pages = {3695-3697}, abstract = {

A spectrometer incorporating a high transition temperature dc superconducting quantum interference device (SQUID) is used to obtain nuclear magnetic resonance signals from protons in mineral oil at room temperature in fields up to 3 mT. The spatial separation between the SQUID magnetometer at 77 K and the sample at room temperature is less than 1 mm. At 2 mT, the signal is easily resolved in a single scan. Two-dimensional images of samples consisting of pieces of lucite or glass immersed in mineral oil are obtained at 2 mT. (C) 1999 American Institute of Physics. [S0003-6951(99)03649-9].

}, keywords = {mri}, isbn = {0003-6951}, doi = {Doi 10.1063/1.125432}, url = {://WOS:000083912800035}, author = {Schlenga, K. and McDermott, R. and Clarke, J. and de Souza, R. E. and Wong-Foy, A. and Pines, A.} } @article {387, title = {NMR and MRI obtained with high transition temperature DC SQUIDs}, journal = {Journal of the Brazilian Chemical Society}, volume = {10}, year = {1999}, note = {J Brazil Chem Soc259BETimes Cited:11Cited References Count:30}, month = {Jul-Aug}, pages = {307-312}, abstract = {

We have measured nuclear magnetic resonance (NMR) signals from several samples at room temperature in magnetic fields ranging from about 0.05 mT to 2 mT using a spectrometer based on a high-T-c de SQUID (high transition temperature de Superconducting QUantum Interference Device). We are able to observe proton signals from 1 mL of mineral oil in 2 mT in a single transient. The sensitivity of this system has also allowed the detection of proton NMR at magnetic fields as low as 0.059 mT, which is comparable to the Earth\&$\#$39;s field. Such results make possible a number of new experiments in magnetic resonance imaging (MRI). We present a two-dimensional image of a phantom filled with mineral oil obtained in a field of 2 mT.

}, keywords = {system}, isbn = {0103-5053}, url = {://WOS:000083873500009}, author = {de Souza, R. E. and Schlenga, K. and Wong-Foy, A. and McDermott, R. and Pines, A. and Clarke, J.} } @article {380, title = {NMR and MRI using laser-polarized xenon}, journal = {Spectroscopy}, volume = {14}, year = {1999}, note = {Spectroscopy216AZTimes Cited:19Cited References Count:65}, month = {Jul}, pages = {26-33}, abstract = {

The application of optical pumping methods increases the nuclear spin polarization of noble gases by four to five orders of magnitude. This enormous increase in polarization translates directly into greatly enhanced signals for nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI). Selected experiments devised to exploit this enhanced sensitivity are reviewed, including xenon NMR/MRI studies of biological systems and polarization transfer to molecules in solution and on surfaces.

}, keywords = {liquid xenon}, isbn = {0887-6703}, url = {://WOS:000081419500003}, author = {Song, Y. Q. and Goodson, B. M. and Pines, A.} } @article {379, title = {NMR study of InP quantum dots: Surface structure and size effects}, journal = {Journal of Chemical Physics}, volume = {110}, year = {1999}, note = {J Chem Phys192HUTimes Cited:30Cited References Count:28}, month = {May 8}, pages = {8861-8864}, abstract = {

We report the results of P-31 NMR measurements on trioctylphosphine oxide (TOPO) passivated InP quantum dots. The spectra show distinct surface-capping sites, implying a manifold of crystal-ligand bonding configurations. Two In P-31 surface components are resolved and related to different electronic surroundings. With decreasing particle size the In P-31 core resonance reveals an increasing upfield chemical shift related to the overall size dependence of the InP electronic structure. (C) 1999 American Institute of Physics. [S0021-9606(99)70718-X].

}, keywords = {clusters}, isbn = {0021-9606}, doi = {Doi 10.1063/1.478858}, url = {://WOS:000080073200002}, author = {Tomaselli, M. and Yarger, J. L. and Bruchez, M. and Havlin, R. H. and deGraw, D. and Pines, A. and Alivisatos, A. P.} } @article {381, title = {NMR with a continuously circulating flow of laser-polarized Xe-129}, journal = {Journal of Physical Chemistry B}, volume = {103}, year = {1999}, note = {J Phys Chem B203HNTimes Cited:45Cited References Count:35}, month = {Jun 3}, pages = {4629-4637}, abstract = {

In this paper we describe the construction of an apparatus for optical pumping of Xe-129 in a circulating gas system connected to a probe for static high-field NMR. The optimal working conditions for the optical pumping under flow are explored, yielding a continuous gas now with a steady-state spin-polarization of about 2\%. It is shown that on various types of high surface area materials a steady-state of adsorbed laser-polarized xenon can be;reached with polarizations of about 0.3\%. NMR spectroscopy of this layer is greatly facilitated due to the renewable magnetization under the continuous-flow conditions allowing unprecedented fast detection of two-dimensional NMR experiments with laser-polarized Xe. The steady-state spin-polarization of adsorbed Xe-129 gives rise to cross-relaxation to surface nuclei such as H-1 and Si-29. A direct spin-polarization-induced nuclear Overhauser effect (SPINOE) to heteronuclei is observed with an enhancement factor of about 20-30. A method is presented for simple modulation of the spin-polarization direction in the fringe field of the high-field magnet; this is exploited to obtain difference SPINOE spectra to highlight only the surface nuclei. Furthermore, a transfer via cross-polarization (CP) from adsorbed Xe to surface protons is demonstrated to select surface groups with reduced mobility compared to SPINOE detection.

}, keywords = {zeolites}, isbn = {1089-5647}, doi = {Doi 10.1021/Jp9821984}, url = {://WOS:000080702600011}, author = {Seydoux, R. and Pines, A. and Haake, M. and Reimer, J. A.} } @book {385, title = {Proc. of the Int. School of Physics, Enrico Fermi Course CXXXIX - Magnetic Resonance and Brain Funtion: Approaches from Physics}, series = {NMR and MRI of Laser-Polarized Noble Gases in Molecules}, year = {1999}, publisher = {IOS Press}, organization = {IOS Press}, chapter = {211-226}, author = {Goodson, B.M. and Kaiser, L. and Pines, A.} } @article {388, title = {Relaxation-selective magnetic resonance imaging}, journal = {Chemical Physics Letters}, volume = {311}, year = {1999}, note = {Chem Phys Lett244VRTimes Cited:1Cited References Count:15}, month = {Oct 1}, pages = {379-384}, abstract = {

The Bloch equations with T-2 relaxation can be inverted in closed form with respect to T-2, using inverse scattering theory. Hence, radio frequency pulses can be calculated that cause a final magnetization response that is any desired function of T-2, provided that function is physically realizable (however, there are strong constraints on what is physically realizable). A useful subclass of such pulses are \&$\#$39;dressing\&$\#$39; pulses, which store the magnetization on the z-axis, with magnitude a given function of T-2. This enables spins to be selectively nulled according to their T-2- this is demonstrated by obtaining a relaxation-selective image of a phantom. (C) 1999 Elsevier Science B.V. All rights reserved.

}, keywords = {optimization}, isbn = {0009-2614}, doi = {Doi 10.1016/S0009-2614(99)00890-8}, url = {://WOS:000083071900007}, author = {Bush, S. D. and Rourke, D. E. and Kaiser, L. G. and Pines, A.} } @article {384, title = {Study of xenon binding in cryptophane-A using laser-induced NMR polarization enhancement}, journal = {Journal of the American Chemical Society}, volume = {121}, year = {1999}, note = {J Am Chem Soc189BTTimes Cited:73Cited References Count:64}, month = {Apr 14}, pages = {3502-3512}, abstract = {

In solution, spin-polarization transfer between laser-polarized xenon and the hydrogen nuclei of nearby molecules leads to signal enhancements in the resolved H-1 NMR spectrum, offering new opportunities for probing the chemical environment of xenon atoms. Following binding of laser-polarized xenon to molecules of cryptophane-A, selective enhancements of the H-1 NMR signals were observed. A theoretical framework for the interpretation of such experimental results is provided, and the spin polarization-induced nuclear Overhauser effects are shown to yield information about the molecular environment of xenon. The observed selective H-1 enhancements allowed xenon-proton internuclear distances to be estimated. These distances reveal structural characteristics of the complex, including the preferred molecular conformations adopted by cryptophane-A upon binding of xenon.

}, keywords = {SPECTROSCOPY}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja9841916}, url = {://WOS:000079884800033}, author = {Luhmer, M. and Goodson, B. M. and Song, Y. Q. and Laws, D. D. and Kaiser, L. and Cyrier, M. C. and Pines, A.} } @article {393, title = {Effects of diffusion on magnetic resonance imaging of laser-polarized xenon gas}, journal = {Journal of Chemical Physics}, volume = {108}, year = {1998}, note = {J Chem PhysZh114Times Cited:30Cited References Count:24}, month = {Apr 15}, pages = {6233-6239}, abstract = {

Molecular diffusion during the application of magnetic field gradients can distort magnetic resonance images. A systematic characterization of these distortions in one dimension was performed using highly spin-polarized xenon gas. By varying the strength of the applied gradient and the geometric dimension of the sample, the evolution of these image distortions between the regimes of strong and weak diffusion was observed. These results are compared with numerical simulations. By directly measuring the displacement distribution of the polarized xenon atoms, it is shown that in the weak-diffusion regime the image distortions originate from the restricted diffusive motion near the sample boundaries, in agreement with previous theoretical work. Additionally, it is shown that the effects of diffusion can be utilized to enhance the contrast between the boundaries and bulk in the images of polarized gas samples, and thus may be exploited as a means of boundary detection in such systems. (C) 1998 American Institute of Physics. [S0021-9606(98)02915-8].

}, keywords = {xe-129}, isbn = {0021-9606}, doi = {Doi 10.1063/1.476030}, url = {://WOS:000073073700018}, author = {Song, Y. Q. and Goodson, B. M. and Sheridan, B. and de Swiet, T. M. and Pines, A.} } @article {404, title = {Enhancement of C-13 NMR signals in solid C-60 and C-70 using laser-polarized xenon}, journal = {Chemical Physics Letters}, volume = {290}, year = {1998}, note = {Chem Phys LettZw963Times Cited:30Cited References Count:31}, month = {Jun 26}, pages = {112-116}, abstract = {

NMR signals emanating from surface nuclei of solids may be enhanced by the transfer of spin polarization from laser-polarized noble gases via SPINOE (spin polarization induced nuclear Overhauser effect). The present contribution describes experiments in which the spin polarization is transferred under magic angle spinning (MAS) from laser-polarized Xe-129 to C-13, a nuclear spin with a low gyromagnetic ratio in the fullerenes C-60 and C-70, polycrystalline materials with a low surface area. In C-70, differential enhancement of the NMR is observed for the different atomic sites in the molecule. (C) 1998 Elsevier Science B.V. All rights reserved.

}, keywords = {c60}, isbn = {0009-2614}, doi = {Doi 10.1016/S0009-2614(98)00473-4}, url = {://WOS:000074466600018}, author = {Brunner, E. and Haake, M. and Pines, A. and Reimer, J. A. and Seydoux, R.} } @article {402, title = {A high-resolution(17)O NMR study of siliceous zeolite faujasite}, journal = {Journal of the American Chemical Society}, volume = {120}, year = {1998}, note = {J Am Chem SocZj097Times Cited:66Cited References Count:19}, month = {Apr 15}, pages = {3510-3511}, keywords = {workstation computers}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja9743001}, url = {://WOS:000073179200032}, author = {Bull, L. M. and Cheetham, A. K. and Anupold, T. and Reinhold, A. and Samoson, A. and Sauer, J. and Bussemer, B. and Lee, Y. and Gann, S. and Shore, J. and Pines, A. and Dupree, R.} } @article {392, title = {Imaging of laser-polarized solid xenon}, journal = {Solid State Nuclear Magnetic Resonance}, volume = {10}, year = {1998}, note = {Solid State Nucl MagZh559Times Cited:5Cited References Count:16}, month = {Feb}, pages = {247-250}, abstract = {

The enhanced spin polarization produced by optical pumping of gaseous rubidium/xenon samples has made possible a number of recent experiments in nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI). Here we report MRI of laser-polarized xenon in the solid phase at low temperature. Due to the high xenon density in the solid phase and the enhanced spin polarization, it is possible to achieve high intensity and spatial resolution of the image. Signals were observed from xenon films solidified onto the glass container walls and not from an enclosed chili pepper. (C) 1998 Elsevier Science B.V.

}, keywords = {gas}, isbn = {0926-2040}, doi = {Doi 10.1016/S0926-2040(97)00078-7}, url = {://WOS:000073123500009}, author = {Song, Y. Q. and Taylor, R. E. and Pines, A.} } @article {400, title = {In situ NMR analysis of fluids contained in sedimentary rock}, journal = {Journal of Magnetic Resonance}, volume = {133}, year = {1998}, note = {J Magn Reson116WNTimes Cited:23Cited References Count:23}, month = {Aug}, pages = {385-387}, abstract = {

Limitations of resolution and absorption in standard chemical spectroscopic techniques have made it difficult to study fluids in sedimentary rocks. In this paper, we show that a chemical characterization of pore fluids may be obtained in situ by magic angle spinning (MAS) nuclear magnetic resonance (NMR), which is normally used for solid samples. H-1 MAS-NMR spectra of water and crude oil in Berea sandstone show sufficient chemical shift resolution for a straightforward determination of the oil/water ratio, (C) 1998 Academic Press.

}, keywords = {oil}, isbn = {1090-7807}, doi = {Doi 10.1006/Jmre.1998.1459}, url = {://WOS:000075748200020}, author = {de Swiet, T. M. and Tomaselli, M. and Hurlimann, M. D. and Pines, A.} } @article {405, title = {Low field magnetic resonance images of polarized noble gases obtained with a dc superconducting quantum interference device}, journal = {Applied Physics Letters}, volume = {72}, year = {1998}, note = {Appl Phys LettZg930Times Cited:37Cited References Count:24}, month = {Apr 13}, pages = {1908-1910}, abstract = {

Using a low transition temperature superconducting quantum interference device as a detector, we have obtained magnetic resonance images of laser-polarized He-3 gas and solid Xe-129 at 4.2 K in magnetic fields as low as 0.54 mT (He-3) and 1 mT (Xe-129), corresponding to Larmor frequencies of 17.6 and 11.8 kHz, respectively. The experimental resolution of the images is similar to 500 mu m for He-3 ill the gas phase and similar to 950 mu m for Xe-129 in the solid state. (C) 1998 American Institute of Physics.

}, keywords = {mri}, isbn = {0003-6951}, doi = {Doi 10.1063/1.121223}, url = {://WOS:000073054300038}, author = {Augustine, M. P. and Wong-Foy, A. and Yarger, J. L. and Tomaselli, M. and Pines, A. and TonThat, D. M. and Clarke, J.} } @article {394, title = {Melvin P. Klein: A short personal and scientific biography}, journal = {Journal of Physical Chemistry B}, volume = {102}, year = {1998}, note = {J Phys Chem B134HHTimes Cited:0Cited References Count:0}, month = {Oct 15}, pages = {8123-8132}, isbn = {1089-5647}, doi = {Doi 10.1021/Jp983371z}, url = {://WOS:000076737100002}, author = {Pines, A.} } @article {396, title = {NMR of supercritical laser-polarized xenon}, journal = {Chemical Physics Letters}, volume = {292}, year = {1998}, note = {Chem Phys Lett112EZTimes Cited:25Cited References Count:35}, month = {Aug 14}, pages = {686-690}, abstract = {

The feasibility of producing supercritical laser-polarized xenon for nuclear magnetic resonance (NMR) investigations was studied. Using a high-pressure capillary tube, a supercritical xenon sample (52 degrees C, 65 atm) was produced with a Xe-129 polarization approximately 140 times the equilibrium value. The polarization was observed to last for hundreds of seconds, in agreement with previous studies. These preliminary results suggest that supercritical laser-polarized xenon may be used as a polarizing solvent for numerous NMR applications. (C) 1998 Published by Elsevier Science B.V. All rights reserved.

}, keywords = {gas}, isbn = {0009-2614}, doi = {Doi 10.1016/S0009-2614(98)00732-5}, url = {://WOS:000075482300049}, author = {Haake, M. and Goodson, B. M. and Laws, D. D. and Brunner, E. and Cyrier, M. C. and Havlin, R. H. and Pines, A.} } @article {399, title = {NMR spectra with peaks at the principal values of the chemical shielding tensor}, journal = {Chemical Physics Letters}, volume = {285}, year = {1998}, note = {Chem Phys LettZf354Times Cited:10Cited References Count:25}, month = {Mar 13}, pages = {59-63}, abstract = {

The NMR chemical shielding in a solid powder sample produces featured, but broad, lineshapes, or powder patterns, because the shielding experienced by a nuclear spin depends on the spatial orientation of its local molecular frame with respect to the external magnetic field. The Lineshape, however, is fully determined by the three principal values of the shielding tenser. We present a simple approach that uses sample spinning NMR to extract peaks at the principal-value frequencies from chemical shielding powder patterns. Such techniques may simplify spectra with overlapping powder patterns without the information loss inherent in fast magic angle spinning. Experimental data and numerical simulations are presented for two P-31 model compounds. (C) 1998 Elsevier Science B.V.

}, keywords = {SPECTROSCOPY}, isbn = {0009-2614}, doi = {Doi 10.1016/S0009-2614(97)01478-4}, url = {://WOS:000072889100010}, author = {de Swiet, T. M. and Tomaselli, M. and Pines, A.} } @book {386, title = {Proc. of the Int. School of Physics, Enrico Fermi Course CXXXIX - Magnetic Resonance and Brain Funtion: Approaches from Physics}, series = {Lectures on Pulsed NMR}, year = {1998}, pages = {210}, publisher = {IOS Press}, organization = {IOS Press}, edition = {3rd}, chapter = {45-210}, author = {Emsley, L. and Laws, D. and Pines, A.} } @article {401, title = {Reversal of radio-frequency-driven spin diffusion by reorientation of the sample spinning axis}, journal = {Journal of Chemical Physics}, volume = {108}, year = {1998}, note = {J Chem PhysYr359Times Cited:9Cited References Count:39}, month = {Jan 15}, pages = {826-829}, abstract = {

The dipolar Hamiltonian in a rapidly rotating sample is scaled by the second Legendre polynomial of the cosine of the angle between the rotation axis and the static magnetic field. It is, therefore, possible to refocus the spatial polarization-transfer process, often termed spin diffusion, in extended spin systems by reorienting the rotor axis such that the dipolar interaction Hamiltonian changes sign. We present experimental results which demonstrate that a rapid mechanical sample reorientation leads to a time reversal of the \"radio-frequency-driven\" spin diffusion among C-13 spins. (C) 1998 American Institute of Physics. [S0021-9606(98)03503-X].

}, keywords = {echoes}, isbn = {0021-9606}, doi = {Doi 10.1063/1.475494}, url = {://WOS:000071487500002}, author = {De Paul, S. M. and Tomaselli, M. and Pines, A. and Ernst, M. and Meier, B. H.} } @article {391, title = {Scalar and anisotropic J interactions in undoped InP: A triple-resonance NMR study}, journal = {Physical Review B}, volume = {58}, year = {1998}, note = {Phys Rev B125HUTimes Cited:29Cited References Count:40}, month = {Oct 1}, pages = {8627-8633}, abstract = {

The heteronuclear J-coupling tensor between nearest neighbor P-31 and In-113 spins in undoped InP is investigated by means of In-113--\>P-31 polarization transfer under rapid magic angle spinning (MAS). The scalar contribution can be measured directly and is found to have the value \J(iso)(P-31-In-113,In-115)\ = (225+/-10) Hz. The principal value of the traceless anisotropic J-coupling tensor (pseudodipolar coupling) is determined to be J(aniso)(P-31-In-113,In-115)= 2/3[J(parallel to)(P-31-In-113,In-115)-J(perpendicular to)(P-31-In-113,In-115)] = (813+/-50) or (1733+/-50) Hz, assuming axial symmetry with the principal axis parallel to the In-P bond. Our values deviate from those reported previously [M. Engelsberg and R. E. Norberg, Phys. Rev. B 5, 3395 (1972)] [based on a moment analysis of the P-31 resonance \J(iso)(31P-In-113,In-115)\ = 350 Hz and J(aniso)(P-31-In-113,In-115) = 1273 Hz], but confirm the postulate that the nearest neighbor P-31-In-113,In-115 magnetic dipolar and pseudodipolar interactions are of the same order of magnitude and partially cancel each other.

}, keywords = {solids}, isbn = {0163-1829}, doi = {Doi 10.1103/Physrevb.58.8627}, url = {://WOS:000076232100075}, author = {Tomaselli, M. and deGraw, D. and Yarger, J. L. and Augustine, M. P. and Pines, A.} } @article {403, title = {Surface NMR using laser-polarized (129)Xe under magic angle spinning conditions}, journal = {Journal of Magnetic Resonance}, volume = {130}, year = {1998}, note = {J Magn ResonZc833Times Cited:46Cited References Count:21}, month = {Jan}, pages = {145-148}, abstract = {

NMR signals of surface nuclei of solids may be enhanced by the transfer of spin polarization from laser-polarized noble gases. Until now such experiments have not been feasible under conditions of magic angle spinning. In the present contribution it is shown that laser-polarized (129)Xe can be inserted into a spinning rotor under continuous-flow conditions using helium as a carrier gas. Effective adsorption of xenon on the sample occurs at temperatures of about 163-173 K making possible the observation of a spin polarization induced nuclear Overhauser effect (SPINOE) from the laser-polarized (129)Xe to surface (1)H nuclei of SiO(2) (AEROSIL300). This technique opens the way to selectively enhanced high-resolution multinuclear surface NMR experiments. (C) 1998 Academic Press.

}, keywords = {flow}, isbn = {1090-7807}, doi = {Doi 10.1006/Jmre.1997.1296}, url = {://WOS:000072622700022}, author = {Brunner, E. and Seydoux, R. and Haake, M. and Pines, A. and Reimer, J. A.} } @article {395, title = {Surface selective H-1/Si-29 CP NMR by NOE enhancement from laser polarized xenon}, journal = {Journal of Magnetic Resonance}, volume = {133}, year = {1998}, note = {J Magn Reson116WNTimes Cited:27Cited References Count:20}, month = {Aug}, pages = {299-303}, abstract = {

The surface proton spin polarization created by the spin-polarization-induced nuclear Overhauser effect from optically polarized xenon can be transferred in a subsequent step by solid-state cross polarization to another nuclear spin species such as Si-29. The technique exploits the dipolar interactions of xenon nuclear spins with high gamma nuclei such as H-1, and is experimentally simpler than direct polarization transfer from Xe-129 to heteronuclei such as C-13 and Si-29. (C) 1998 Academic Press.

}, keywords = {spins}, isbn = {1090-7807}, doi = {Doi 10.1006/Jmre.1998.1447}, url = {://WOS:000075748200008}, author = {Pietrass, T. and Seydoux, R. and Pines, A.} } @article {398, title = {Time reversal of cross-polarization in solid-state NMR}, journal = {Molecular Physics}, volume = {95}, year = {1998}, note = {Mol Phys146XYTimes Cited:4Cited References Count:21}, month = {Dec 10}, pages = {849-858}, abstract = {

Cross-polarization at the Hartmann-Hahn condition in solid-state NMR frequently is described in terms of thermodynamics. Spin temperatures characterizing the canonical density operator are assigned to the Zeeman reservoirs of the two spins and the cross-polarization process brings about a state of equilibrium of the two reservoirs with a common temperature. In such a model, cross-polarization from an initially polarized spin species (I spins) to another spin species (S spins) is inherently an irreversible process accompanied by an increase in the entropy of the system. However, a cross-polarization echo can be generated whereby the polarization transferred to the S spins returns to the I spins, restoring the initial density operator. Therefore a thermodynamic description should be applied with care even in samples where the build-up and the decay of the magnetization can be approximated well by multiexponential processes. Such cross-polarization echoes are formed by the consecutive application of two pulse trains that produce effective Hamiltonians differing in sign. The \&$\#$39;time reversal\&$\#$39; of cross-polarization is consistent with both the increase in Zeeman entropy during the approach to equilibrium and with the constraint of unitary quantum evolution.

}, keywords = {echoes}, isbn = {0026-8976}, doi = {Doi 10.1080/002689798166477}, url = {://WOS:000077460200014}, author = {Ernst, M. and Meier, B. H. and Tomaselli, M. and Pines, A.} } @article {397, title = {Time-reversal of cross-polarization in nuclear magnetic resonance}, journal = {Journal of Chemical Physics}, volume = {108}, year = {1998}, note = {J Chem Phys108FUTimes Cited:11Cited References Count:17}, month = {Jun 15}, pages = {9611-9613}, abstract = {

It is demonstrated that the time evolution of the heteronuclear polarization-transfer process in a dipolar-coupled nuclear spin system can be reversed, leading to the observation of cross polarization echoes. The cross-polarization echoes are induced by consecutive application of two pulse trains that produce effective Hamiltonians that differ only in sign, Cross-polarization echoes have been recorded for a powder sample of alanine. The time evolution of the spin;system is consistent with both unitary quantum dynamics and with spin thermodynamics of two systems approaching a common spin temperature. (C) 1998 American Institute of Physics.

}, keywords = {echoes}, isbn = {0021-9606}, doi = {Doi 10.1063/1.476435}, url = {://WOS:000075256100001}, author = {Ernst, M. and Meier, B. H. and Tomaselli, M. and Pines, A.} } @article {412, title = {Bubbling NMR polarization onto surfaces and into solution.}, journal = {Abstracts of Papers of the American Chemical Society}, volume = {214}, year = {1997}, note = {Abstr Pap Am Chem SPart 2Xq859Times Cited:0Cited References Count:0}, month = {Sep 7}, pages = {378-PHYS}, isbn = {0065-7727}, author = {Pines, A.} } @article {417, title = {Cross-polarization efficiency in INS systems using adiabatic RF sweeps}, journal = {Journal of Chemical Physics}, volume = {107}, year = {1997}, note = {J Chem PhysYj464Times Cited:13Cited References Count:33}, month = {Dec 1}, pages = {8742-8751}, abstract = {

The theory describing nuclear magnetic resonance cross-polarization using adiabatic sweeps of the rf spin-lock fields through the Hartmann-Hahn matching condition is extended to small homonuclear coupled systems of the type INS. In particular, the connection is made between such experiments and the associated theoretical limits on polarization transfer-the \&$\#$39;\&$\#$39;unitary bounds\&$\#$39;\&$\#$39; - demonstrating that these techniques can achieve the maximum transfer of polarization from the I spins to the S spins, subject to the constraint of angular momentum conservation imposed by spin-locking, Factors such as permutation symmetry of the spins, imperfect adiabaticity of individual crossings and fast sample spinning are shown to have no fundamental impact on the validity on these results. (C) 1997 American Institute of Physics.

}, keywords = {bounds}, isbn = {0021-9606}, doi = {Doi 10.1063/1.475167}, url = {://WOS:A1997YJ46400002}, author = {Hodgkinson, P. and Pines, A.} } @article {421, title = {Cross-polarization from quadrupolar nuclei to silicon using low-radio-frequency amplitudes during magic-angle spinning}, journal = {Journal of Physical Chemistry B}, volume = {101}, year = {1997}, note = {J Phys Chem BWu630Times Cited:51Cited References Count:50}, month = {Apr 17}, pages = {3240-3249}, abstract = {

The dynamics of cross-polarization from the central transition of a quadrupolar nucleus (Al-27 or Na-23) to a spin-1/2 nucleus (Si-29) during magic-angle spinning and using low-radio-frequency Geld strengths are analyzed for the mineral low albite. Under these conditions additional complications in the spin-lock behavior of the quadrupolar nucleus and in the cross-polarization process were found experimentally and are examined in detail. A step-by-step procedure for optimizing cross-polarization from the central transition of a quadrupolar nucleus to a spin-1/2 nucleus is described. Significant enhancement of Si-29 NMR sensitivity and several applications are demonstrated.

}, keywords = {locking}, isbn = {1089-5647}, doi = {Doi 10.1021/Jp9623711}, url = {://WOS:A1997WU63000031}, author = {DePaul, S. M. and Ernst, M. and Shore, J. S. and Stebbins, J. F. and Pines, A.} } @article {418, title = {Determination of dihedral angles in peptides through experimental and theoretical studies of alpha-carbon chemical shielding tensors}, journal = {Journal of the American Chemical Society}, volume = {119}, year = {1997}, note = {J Am Chem SocXt037Times Cited:90Cited References Count:57}, month = {Aug 20}, pages = {7827-7831}, abstract = {

A simple method for the determination of backbone dihedral angles in peptides and proteins is presented. The chemical-shift anisotropies (CSA) of the central alanine alpha-carbon in powdered crystalline tripeptides, whose structures have been determined previously by X-ray crystallography, were measured by cross-polarization magic-angle-spinning nuclear magnetic resonance. The experimental CSA values were correlated with ab initio chemical-shielding calculations over Ramanchandran phi/psi space on an N-formyl-L-alanine amide fragment. Using this correlation, phi/psi probability surfaces for one of the tripeptides were calculated based only on the alpha-carbon CSA, allowing a prediction of backbone angles. Dihedral angles predicted by these calculations fall within +/-12 degrees of the values determined by crystallography. This approach should be useful in the determination of solid-slate protein structure.

}, keywords = {crystal-structure}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja970124k}, url = {://WOS:A1997XT03700025}, author = {Heller, J. and Laws, D. D. and Tomaselli, M. and King, D. S. and Wemmer, D. E. and Pines, A. and Havlin, R. H. and Oldfield, E.} } @article {411, title = {Enhancement of surface NMR by laser-polarized noble gases}, journal = {Physical Review B}, volume = {55}, year = {1997}, note = {Phys Rev BWy504Times Cited:65Cited References Count:34}, month = {May 1}, pages = {11604-11610}, abstract = {

The transfer of spin polarization from laser-polarized helium and xenon to spins such as H-1 and C-13 On the surface of high-surface-area solids (Aerosil) is demonstrated over a temperature range from 4 to 200 K. The transfer mechanism is dipole-dipole cross relaxation between the spins of the adsorbed mobile noble gas and the surface spins (spin-polarization-induced nuclear Overhauser effect). The enhancement of surface proton magnetization by laser-polarized helium at 4 K and 10 K is between one and twofold. Using laser-polarized xenon, enhancement factors of up to 20 were obtained when compared to the Boltzmann polarization in a field of 4.2 T and at a temperature of 130 K.

}, keywords = {he-3}, isbn = {0163-1829}, doi = {Doi 10.1103/Physrevb.55.11604}, url = {://WOS:A1997WY50400096}, author = {Room, T. and Appelt, S. and Seydoux, R. and Hahn, E. L. and Pines, A.} } @article {416, title = {Geometric dephasing in zero-field magnetic resonance}, journal = {Journal of Chemical Physics}, volume = {106}, year = {1997}, note = {J Chem PhysWh843Times Cited:8Cited References Count:28}, month = {Feb 22}, pages = {3007-3016}, abstract = {

Geometric phases acquired randomly can give rise to coherence dephasing in nuclear spin systems, equivalent to spin relaxation. We calculate the form and extent of this geometric dephasing in a number of model systems involving the motion of Xe-131 nuclei in shaped containers. The dephasing is calculated in two ways: first, using an analytical treatment of the diffusive motion of individual nuclei, and second, using ensemble averaged propagators. The effects of applying additional magnetic fields to these systems are discussed briefly. (C) 1997 American Institute of Physics.

}, keywords = {xenon}, isbn = {0021-9606}, doi = {Doi 10.1063/1.473046}, url = {://WOS:A1997WH84300003}, author = {Jones, J. A. and Pines, A.} } @article {420, title = {In vivo NMR and MRI using injection delivery of laser-polarized xenon}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {94}, year = {1997}, note = {P Natl Acad Sci USAYn574Times Cited:55Cited References Count:39}, month = {Dec 23}, pages = {14725-14729}, abstract = {

Because xenon NMR is highly sensitive to the local environment, laser-polarized xenon could be a unique probe of living tissues. Realization of clinical and medical science applications beyond lung airspace imaging requires methods of efficient delivery of laser-polarized xenon to tissues, because of the short spin-lattice relaxation times and relatively low concentrations of xenon attainable in the body. Preliminary results from the application of a polarized xenon injection technique for in vivo Xe-129 NMR/MRI are extrapolated along with a simple model of xenon transit to show that the peak local concentration of polarized xenon delivered to tissues by injection may exceed that delivered by respiration by severalfold.

}, keywords = {humans}, isbn = {0027-8424}, doi = {Doi 10.1073/Pnas.94.26.14725}, url = {://WOS:000071182800090}, author = {Goodson, B. M. and Song, Y. Q. and Taylor, R. E. and Schepkin, V. D. and Brennan, K. M. and Chingas, G. C. and Budinger, T. F. and Navon, G. and Pines, A.} } @article {408, title = {Low magnetic field dynamic nuclear polarization using a single-coil two-channel probe}, journal = {Review of Scientific Instruments}, volume = {68}, year = {1997}, note = {Rev Sci InstrumWp247Times Cited:4Cited References Count:29}, month = {Mar}, pages = {1527-1531}, abstract = {

We describe the design and construction of a single-coil, two-channel probe for the detection of low-field magnetic resonance using dynamic nuclear polarization (DNP). The high-frequency channel of the probe, which is used to saturate the electron spins, is tuned to the electron Larmor frequency, 75 MHz at 2.7 mT, and matched to 50 Omega. Low-field, H-1 nuclear magnetic resonance (NMR) is detected through the second, low-frequency channel at frequencies \<1 MHz. The performance of the probe was tested by measuring the DNP of protons in a manganese (II) chloride solution at 2.7 mT. At the proton NMR frequency of 120 kHz, the signal amplitude was enhanced over the value without DNP by a factor of about 200. (C) 1997 American Institute of Physics.

}, keywords = {nmr}, isbn = {0034-6748}, doi = {Doi 10.1063/1.1147641}, url = {://WOS:A1997WP24700033}, author = {TonThat, D. M. and Augustine, M. P. and Pines, A. and Clarke, J.} } @article {406, title = {Multiple-quantum magic-angle spinning and dynamic-angle spinning NMR spectroscopy of quadrupolar nuclei}, journal = {Solid State Nuclear Magnetic Resonance}, volume = {8}, year = {1997}, note = {Solid State Nucl MagWy629Times Cited:60Cited References Count:40}, month = {Mar}, pages = {1-16}, abstract = {

Several aspects of the Multiple-Quantum Magic-Angle Spinning (MQMAS) technique (L, Frydman and J,S, Harwood, J, Am, Chem, Sec., 117 (1995) 5367) are compared with Dynamic-Angle Spinning (DAS), Examples of MQMAS spectra are shown for I = 3/2 nuclei with C-Q up to 3.6 MHz, and for: Al-27 (I = 5/2) with C-Q up to 10 MHz. The MQMAS linewidth is largely independent of the magnitude of the homonuclear dipolar interaction, while the spinning sideband manifold is similar to that observed in DAS experiments, MQMAS is technically simple and routinely useful for studying nuclei with short spin-lattice relaxation times, but care must be taken in its use for quantitative studies as the excitation of the triple-quantum coherence is not uniform, In this regard, MQMAS is most useful for samples with small quadrupolar coupling constants, In the specific case of O-17, DAS would give spectra with excellent resolution in comparison to MQMAS, The different advantages of DAS and MQMAS make them useful complementary techniques in many cases,Two additional methods are also presented for extracting the chemical shift anisotropy (CSA) directly for quadrupolar nuclei using the multiple-quantum scheme, (C) 1997 Elsevier Science B,V.

}, keywords = {rb-87}, isbn = {0926-2040}, doi = {Doi 10.1016/S0926-2040(96)01277-5}, url = {://WOS:A1997WY62900001}, author = {Wang, S. H. and Xu, Z. and Baltisberger, J. H. and Bull, L. M. and Stebbins, J. F. and Pines, A.} } @article {415, title = {A novel detection-estimation scheme for noisy NMR signals: Applications to delayed acquisition data}, journal = {Journal of Magnetic Resonance}, volume = {128}, year = {1997}, note = {J Magn ResonYc696Times Cited:47Cited References Count:59}, month = {Sep}, pages = {30-41}, abstract = {

Many potentially interesting and useful classes of NMR experiments generate data for which conventional spectral estimation and quantification aa the Fourier transform are unsatisfactory. In particular, recently introduced solid-state NMR experiments which involve long delays before data acquisition fall into this category, as the free induction decays are heavily \&$\#$39;\&$\#$39;truncated\&$\#$39;\&$\#$39; and have low signal-to-noise ratios. A novel detection-estimation scheme is introduced in order to analyze data from such experiments and others where the sensitivity is low and/or the data record is strongly damped or truncated, Based on the assumption of exponential data modeling, the number of signals present is first detected using criteria derived from information theory and the spectral parameters are then estimated using the matrix pencil method, Monte Carlo simulations and experimental. applications are carried out to demonstrate its superior statistical and computational performances and its general applicability to delayed acquisition data. Over the range of note levels investigated, it is found that this approach is essentially near-optimal in the sense that the estimated spectral parameters have biases almost equal to zero and variances very close to their theoretical Cramer-Rao lower bounds. Compared to the popular method of linear prediction with singular value decomposition, this method not only improves the estimation accuracy (by a factor of 2-4) with a lower \&$\#$39;\&$\#$39;break-down\&$\#$39;\&$\#$39; signal-to-noise threshold (approximate to 1.5 dB), but also reduces the computational cost by about an order of magnitude, It also holds great promise in effectively reducing truncation artifacts. It is concluded that this approach not only facilitates the analysis of delayed acquisition data, but can also become a valuable tool in the routine quantification of general NMR spectra, ia listing of programs is also included in the Appendix. (C) 1997 Academic Press.

}, keywords = {resolution}, isbn = {1090-7807}, doi = {Doi 10.1006/Jmre.1997.1215}, url = {://WOS:A1997YC69600004}, author = {Lin, Y. Y. and Hodgkinson, P. and Ernst, M. and Pines, A.} } @article {410, title = {Optical magnetic resonance imaging of Rb vapor in low magnetic fields}, journal = {Physics Letters A}, volume = {226}, year = {1997}, note = {Phys Lett AWf939Times Cited:12Cited References Count:19}, month = {Feb 10}, pages = {69-74}, abstract = {

By applying magnetic field gradients to alkali vapor cells, images of the spatial distribution of spin-polarized Rb atoms were obtained. Optical pumping is used to produce precessing spin-polarization in the ground state. Detection of the coherent spin transients is performed in the time-domain by a single optical probe beam covering the whole sample cell. Spatial resolution of better than 1 mm has been achieved by a projection-reconstruction method.

}, keywords = {xe-129}, isbn = {0375-9601}, doi = {Doi 10.1016/S0375-9601(96)00927-9}, url = {://WOS:A1997WF93900012}, author = {Skalla, J. and Wackerle, G. and Mehring, M. and Pines, A.} } @article {413, title = {P-31 to Se-77 cross polarization in beta-P4Se3}, journal = {Solid State Nuclear Magnetic Resonance}, volume = {8}, year = {1997}, note = {Solid State Nucl MagYd904Times Cited:7Cited References Count:12}, month = {Aug}, pages = {265-267}, abstract = {

Cross polarization from P-31 to Se-77 is demonstrated in beta-P4Se3. This material, an inorganic glass, is readily synthesized from the elements and serves as a convenient sample for setting the Hartmann-Hahn condition. (C) 1997 Elsevier Science B.V.

}, keywords = {f-19}, isbn = {0926-2040}, doi = {Doi 10.1016/S0926-2040(97)00012-X}, url = {://WOS:A1997YD90400008}, author = {Pietrass, T. and Seydoux, R. and Roth, R. E. and Eckert, H. and Pines, A.} } @article {409, title = {Selective enhancement of NMR signals for alpha-cyclodextrin with laser-polarized xenon}, journal = {Angewandte Chemie-International Edition in English}, volume = {36}, year = {1997}, note = {Angew Chem Int EditYh944Times Cited:48Cited References Count:29}, month = {Nov 14}, pages = {2368-2370}, keywords = {solids}, isbn = {0570-0833}, doi = {Doi 10.1002/Anie.199723681}, url = {://WOS:A1997YH94400025}, author = {Song, Y. Q. and Goodson, B. M. and Taylor, R. E. and Laws, D. D. and Navon, G. and Pines, A.} } @article {414, title = {Spin dynamics in dipole-coupled molecular systems}, journal = {Abstracts of Papers of the American Chemical Society}, volume = {214}, year = {1997}, note = {Abstr Pap Am Chem SPart 2Xq859Times Cited:0Cited References Count:0}, month = {Sep 7}, pages = {22-PHYS}, isbn = {0065-7727}, url = {://WOS:A1997XQ85900540}, author = {Lin, Y. Y. and Pines, A.} } @article {407, title = {SQUID detected NMR of laser-polarized xenon at 4.2 K and at frequencies down to 200 Hz}, journal = {Chemical Physics Letters}, volume = {272}, year = {1997}, note = {Chem Phys LettXh440Times Cited:18Cited References Count:32}, month = {Jun 27}, pages = {245-249}, abstract = {

A spectrometer based on a dc SQUID (superconducting quantum interference device) was used to record nuclear magnetic resonance signals from laser-polarized Xe-129 at 4.2 K and at frequencies ranging from about 200 Hz to 110 kHz in magnetic fields varying from about 0.02 to 9 mT. The Xe-129 resonance linewidths were found to increase with increasing magnetic field, and, at a given field, to increase with higher Xe-129 concentration. The spin-lattice relaxation times were observed to decrease from similar to 8000 s at 5 mT to similar to 2000 s at fields below 0.05 mT. Such long relaxation times make possible a variety of spin polarization transfer experiments. (C) 1997 Published by Elsevier Science B.V.

}, keywords = {relaxation}, isbn = {0009-2614}, doi = {Doi 10.1016/S0009-2614(97)88016-5}, url = {://WOS:A1997XH44000017}, author = {TonThat, D. M. and Ziegeweid, M. and Song, Y. Q. and Munson, E. J. and Appelt, S. and Pines, A. and Clarke, J.} } @article {419, title = {Surface-enhanced NMR using continuous-flow laser-polarized xenon}, journal = {Journal of the American Chemical Society}, volume = {119}, year = {1997}, note = {J Am Chem SocYk502Times Cited:66Cited References Count:16}, month = {Dec 3}, pages = {11711-11712}, keywords = {solids}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja9713587}, url = {://WOS:A1997YK50200029}, author = {Haake, M. and Pines, A. and Reimer, J. A. and Seydoux, R.} } @article {428, title = {Application of rotational resonance to inhomogeneously broadened systems}, journal = {Chemical Physics Letters}, volume = {251}, year = {1996}, note = {Chem Phys LettUd924Times Cited:17Cited References Count:28}, month = {Mar 22}, pages = {223-229}, abstract = {

A protocol is presented for the determination of internuclear distances using rotational-resonance magnetization-exchange NMR in systems with inhomogeneously broadened lines. Non-linear least-square fitting procedures are used to obtain the distance, the inhomogeneous broadening, the zero-quantum relaxation time, and error estimates for these parameters. We apply this procedure to a biological system of unknown structure.

}, keywords = {nmr}, isbn = {0009-2614}, doi = {Doi 10.1016/0009-2614(96)00098-X}, url = {://WOS:A1996UD92400015}, author = {Heller, J. and Larsen, R. and Ernst, M. and Kolbert, A. C. and Baldwin, M. and Prusiner, S. B. and Wemmer, D. E. and Pines, A.} } @article {422, title = {Determination of quadrupolar and chemical shielding tensors using solid-state two-dimensional NMR spectroscopy}, journal = {Journal of Chemical Physics}, volume = {105}, year = {1996}, note = {J Chem PhysVv625Times Cited:18Cited References Count:40}, month = {Dec 1}, pages = {9412-9420}, abstract = {

The quadrupolar and chemical shift tensors, as well as the relative orientation of the two principle axis systems, are accurately determined using a two-dimensional nuclear magnetic resonance technique. Good agreement between experimental and simulated two-dimensional spectra is obtained for a series of rubidium and sodium compounds at multiple magnetic field strengths. Extension of this technique to correlate the quadrupolar and dipolar interactions, as well as the incorporation of a purely isotropic dimension resulting in a three-dimensional experiment is also discussed. (C) 1996 American Institute of Physics.

}, keywords = {line-shapes}, isbn = {0021-9606}, doi = {Doi 10.1063/1.472776}, url = {://WOS:A1996VV62500003}, author = {Shore, J. S. and Wang, S. H. and Taylor, R. E. and Bell, A. T. and Pines, A.} } @article {426, title = {Enhancement of solution NMR and MRI with laser-polarized xenon}, journal = {Science}, volume = {271}, year = {1996}, note = {ScienceUc778Times Cited:230Cited References Count:41}, month = {Mar 29}, pages = {1848-1851}, abstract = {

Optical pumping with laser light can be used to polarize the nuclear spins of gaseous xenon-129. When hyperpolarized xenon-129 is dissolved in liquids, a time-dependent departure of the proton spin polarization from its thermal equilibrium is observed, The variation of the magnetization is an unexpected manifestation of the nuclear Overhauser effect, a consequence of cross-relaxation between the spins of solution protons and dissolved xenon-129. Time-resolved magnetic resonance images of both nuclei in solution show that the proton magnetization is selectively perturbed in regions containing spin-polarized xenon-129. This effect could find use in nuclear magnetic resonance spectroscopy of surfaces and proteins and in magnetic resonance imaging.

}, keywords = {resonance}, isbn = {0036-8075}, doi = {Doi 10.1126/Science.271.5257.1848}, url = {://WOS:A1996UC77800041}, author = {Navon, G. and Song, Y. Q. and Room, T. and Appelt, S. and Taylor, R. E. and Pines, A.} } @article {424, title = {Failed Failure}, journal = {The NMR Newsletter}, year = {1996}, author = {Pines, A.} } @article {430, title = {Isotropic second-order dipolar shifts in the rotating frame}, journal = {Journal of Chemical Physics}, volume = {104}, year = {1996}, note = {J Chem PhysUm909Times Cited:9Cited References Count:44}, month = {Jun 1}, pages = {8258-8268}, abstract = {

An experiment is described that utilizes the truncation of the Hamiltonian in the rotating frame by a radio-frequency field designed to yield an isotropic shift for the dipolar coupling. This approach allows the measurement of a normally orientation-dependent coupling constant by a single isotropic value. The dipolar isotropic shift is closely related to the field-dependent chemical shift in solids due to the second-order dipolar perturbation observed in magic-angle spinning experiments. In the rotating frame, larger shifts of up to 1000 Hz can be observed for the case of a one-bond C-H coupling compared to a shift of a few Hertz in the laboratory-frame experiment. In addition to the isotropic shift, a line broadening due to the P-4(cos beta) terms is observed when the experiment is carried out under magic-angle sample spinning (MAS) conditions, leading to the requirement of higher-order averaging such as double rotation (DOR) for obtaining narrow lines. As an application of this new experiment the separation of CH, CH2, and CH3 groups in a 2D spectrum under MAS is demonstrated. Implemented under DOR it could be used as a technique to select carbon atoms according to the number of directly attached protons. (C) 1996 American Institute of Physics.

}, keywords = {spins}, isbn = {0021-9606}, doi = {Doi 10.1063/1.471579}, url = {://WOS:A1996UM90900008}, author = {Ernst, M. and Kolbert, A. C. and Schmidt-Rohr, K. and Pines, A.} } @article {427, title = {Measurement and assignment of long-range C-H dipolar couplings in liquid crystals by two-dimensional NMR spectroscopy}, journal = {Journal of Physical Chemistry}, volume = {100}, year = {1996}, note = {J Phys Chem-UsVe373Times Cited:41Cited References Count:22}, month = {Aug 29}, pages = {14815-14822}, abstract = {

We describe multidimensional NMR techniques to measure and assign C-13-H-1 dipolar couplings in nematic liquid crystals with high resolution. In particular, dipolar couplings between aromatic and aliphatic sites are extracted, providing valuable information on the structural correlations between these two components of thermotropic liquid crystal molecules. The NMR techniques are demonstrated on 4-pentyl-4\&$\#$39;-biphenylcarbonitrile (5CB), a well-characterized room-temperature nematic liquid crystal. Proton-detected local-field NMR spectroscopy is employed to obtain highly resolved C-H dipolar couplings that are separated according to the chemical shifts of the carbon sites. Each C-13 cross section in the 2D spectra exhibits several doublet splittings, with the largest one resulting from the directly bonded C-H coupling, The smaller splittings originate from the long-range C-H dipolar couplings and can be assigned qualitatively by a chemical shift heteronuclear correlation (HETCOR) experiment. The HETCOR experiment incorporates a mixing period for proton spin diffusion to occur, so that maximal polarization transfer can be achieved between the unbonded C-13 and H-1 nuclei. To assign the long-range C-H couplings quantitatively, we combined these two techniques into a novel reduced-3D experiment, in which the H-1 chemical shift-displaced C-H dipolar couplings are correlated with the C-13 chemical shifts. The time domain of this experiment involves separate but synchronous incrementation of the evolution periods for the C-H dipolar couplings and the H-1 chemical shifts, with a variable ratio of the respective dwell times to optimize the resolution and facilitate resonance assignment in the spectrum.

}, keywords = {shape}, isbn = {0022-3654}, doi = {Doi 10.1021/Jp960972m}, url = {://WOS:A1996VE37300036}, author = {Hong, M. and Pines, A. and Caldarelli, S.} } @article {432, title = {Measurement of carbon-proton dipolar couplings in liquid crystals by local dipolar field NMR spectroscopy}, journal = {Journal of Physical Chemistry}, volume = {100}, year = {1996}, note = {J Phys Chem-UsVv354Times Cited:54Cited References Count:31}, month = {Nov 28}, pages = {18696-18701}, abstract = {

The performance of several different two-dimensional NMR methods for the measurement of carbon-proton dipolar couplings in liquid crystalline phases is analyzed. Proton-detected local field spectroscopy allows the measurements of short range C-H couplings, which correspond to directly bond pairs, by direct inspection of the spectra. Off magic angle (OMAS) spinning techniques can be applied to anisotropic phases that can be oriented mechanically at an angle to the magnetic field, such as nematic phases. The consequent scaling of the chemical shift anisotropy and dipolar couplings can be used to resolve otherwise overlapping resonances, Moreover, an estimate of the accuracy of the technique can be achieved by performing a series of OMAS experiments with different sample orientations.

}, keywords = {solids}, isbn = {0022-3654}, doi = {Doi 10.1021/Jp962023z}, url = {://WOS:A1996VV35400008}, author = {Caldarelli, S. and Hong, M. and Emsley, L. and Pines, A.} } @article {433, title = {NMR of laser-polarized xenon in human blood}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {93}, year = {1996}, note = {P Natl Acad Sci USAVt054Times Cited:92Cited References Count:27}, month = {Nov 12}, pages = {12932-12936}, abstract = {

By means of optical pumping with laser light it is possible to enhance the nuclear spin polarization of gaseous xenon by four to five orders of magnitude, The enhanced polarization has allowed advances in nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI), including polarization transfer to molecules and imaging of lungs and other void spaces, A critical issue for such applications is the delivery of xenon to the sample while maintaining the polarization, Described herein is an efficient method for the introduction of laser-polarized xenon into systems of biological and medical interest for the purpose of obtaining highly enhanced NMR/MRI signals. Using this method, we have made the first observation of the time-resolved process of xenon penetrating the red blood cells in fresh human blood-the xenon residence time constant in the red blood cells was measured to be 20.4+/-2 ms. The potential of certain biologically compatible solvents for delivery of laser-polarized xenon to tissues for NMR/MRI is discussed in light of their respective relaxation and partitioning properties.

}, keywords = {gas}, isbn = {0027-8424}, doi = {Doi 10.1073/Pnas.93.23.12932}, url = {://WOS:A1996VT05400048}, author = {Bifone, A. and Song, Y. Q. and Seydoux, R. and Taylor, R. E. and Goodson, B. M. and Pietrass, T. and Budinger, T. F. and Navon, G. and Pines, A.} } @article {434, title = {Rotational diffusion measurements of suspended colloidal particles using two-dimensional exchange nuclear magnetic resonance}, journal = {Journal of Chemical Physics}, volume = {104}, year = {1996}, note = {J Chem PhysTn837Times Cited:13Cited References Count:24}, month = {Jan 8}, pages = {509-520}, abstract = {

We present here an experimental and theoretical study of the application of two-dimensional exchange nuclear magnetic resonance spectroscopy (NMR) to the investigation of the rotational diffusion of colloidal particles. The theoretical discussion includes the nature of the NMR frequency time-correlation function where the NMR interaction is represented by the chemical shift anisotropy (CSA). Time-correlation functions for the isotropic rotational diffusion of a suspension of colloidal particles containing single and multiple sites are derived in addition to time-correlation functions for the rotational diffusion of a suspension of symmetric top particles containing an isotropic distribution of a single CSA interaction. Simulations of two-dimensional exchange spectra for particles undergoing isotropic rotational diffusion are presented. We performed two-dimensional exchange NMR experiments on a colloidal suspension of spherical poly(methyl methacrylate) (PMMA) particles which were synthesized with a 20\% enrichment in C-13 at the carbonyl site. Rotational diffusion time-correlation functions determined from the experimental exchange spectra are consistent with the composition of the colloidal suspension. Detailed explanations of the syntheses of the enriched methyl C-13-(carbonyl)-methacrylate monomer and the small quantities of 20\% enriched C-13-(carbonyl)-poly(methyl methacrylate) microspheres used for this study are presented. (C) 1996 American Institute of Physics.

}, keywords = {scattering}, isbn = {0021-9606}, doi = {Doi 10.1063/1.470847}, url = {://WOS:A1996TN83700009}, author = {Barrall, G. A. and Schmidt-Rohr, K. and Lee, Y. K. and Landfester, K. and Zimmermann, H. and Chingas, G. C. and Pines, A.} } @article {431, title = {Second-order recoupling of chemical-shielding and dipolar-coupling tensors under spin decoupling in solid-state NMR}, journal = {Journal of Chemical Physics}, volume = {105}, year = {1996}, note = {J Chem PhysVd768Times Cited:55Cited References Count:53}, month = {Sep 1}, pages = {3387-3397}, abstract = {

The source of the residual line broadening in continuous-wave (cw) decoupled spectra under magic-angle sample spinning conditions is reexamined. It is shown that an important contribution to the line broadening comes from a second-order recoupling of the heteronuclear dipolar-coupling tensor and the chemical-shielding tensor of the irradiated spin. Such an interference between the two tensors leads to a sum of a zeroth-rank, a second-rank, and a fourth-rank tensor component in the Hamiltonian. The zeroth-rank and the fourth-rank tensor components are not averaged out under magic-angle sample spinning (MAS) conditions, requiring the use of higher-order averaging such as double rotation (DOR) for obtaining narrow lines. This broadening is distinctly different from off-resonance decoupling effects which transform as a second-rank tensor and can be averaged out by MAS. The properties of this second-order recoupling as a source of structural information are explored, and the conditions for removing the broadening in systems with weak homonuclear dipolar-coupling networks are discussed. (C) 1996 American Institute of Physics.

}, keywords = {waltz-16}, isbn = {0021-9606}, doi = {Doi 10.1063/1.472224}, url = {://WOS:A1996VD76800005}, author = {Ernst, M. and Bush, S. and Kolbert, A. C. and Pines, A.} } @article {425, title = {Si-29 high resolution solid state nuclear magnetic resonance spectroscopy of porous silicon}, journal = {Journal of Non-Crystalline Solids}, volume = {202}, year = {1996}, note = {J Non-Cryst SolidsVe406Times Cited:13Cited References Count:33}, month = {Jul}, pages = {68-76}, abstract = {

Porous silicon has been characterized by Si-29 nuclear magnetic resonance spectroscopy under conditions of static samples, magic angle spinning, decoupling and cross polarization. In a free induction decay experiment, two Si-29 resonances at -80 and -111 ppm were obtained. Cross polarization resulted in a single resonance at -97 ppm. Magic angle spinning and decoupling slightly reduce the linewidth of the Si-29 cross polarized signal, The minor narrowing effect and thr relaxation behavior in the laboratory and rotating frame indicate a homogeneous contribution to the linewidth. The relaxation data suggest that the resonance observed under cross polarization conditions arises from SiH or SiH2 structural elements.

}, keywords = {dipolar}, isbn = {0022-3093}, doi = {Doi 10.1016/0022-3093(96)00144-5}, url = {://WOS:A1996VE40600008}, author = {Pietrass, T. and Bifone, A. and Roth, R. D. and Koch, V. P. and Alivisatos, A. P. and Pines, A.} } @booklet {423, title = {Solid-State NMR: Some Personal Recollections}, journal = {Encyclopedia of Nuclear Magnetic Resonance - Historical Perspectives}, volume = {1}, year = {1996}, pages = {533-540}, publisher = {John Wiley \& Sons}, author = {Pines, A.}, editor = {Harris, D.M. Grant and R.K.} } @article {429, title = {Solid-state NMR studies of the prion protein H1 fragment}, journal = {Protein Science}, volume = {5}, year = {1996}, note = {Protein SciVa138Times Cited:74Cited References Count:53}, month = {Aug}, pages = {1655-1661}, abstract = {

Conformational changes in the prion protein (PrP) seem to be responsible for prion diseases. We have used conformation-dependent chemical-shift measurements and rotational-resonance distance measurements to analyze the conformation of solid-state peptides lacking long-range order, corresponding to a region of PrP designated H1. This region is predicted to undergo a transformation of secondary structure in generating the infectious form of the protein. Solid-state NMR spectra of specifically C-13-enrrched samples of H1, residues 109-122 (MKHMAGAAAAGAVV) of Syrian hamster PrP, have been acquired under cross-polarization and magic-angle spinning conditions. Samples lyophilized from 50\% acetonitrile/50\% water show chemical shifts characteristic of a beta-sheet conformation in the region corresponding to residues 112-121, whereas samples lyophilized from hexafluoroisopropanol display shifts indicative of alpha-helical secondary structure in the region corresponding to residues 113-117. Complete conversion to the helical conformation was not observed and conversion from alpha-helix back to beta-sheet, as inferred from the solid-state NMR spectra, occurred when samples were exposed to water. Rotational-resonance experiments were performed on seven doubly C-13-labeled H1 samples dried from water. Measured distances suggest that the peptide is in an extended, possibly beta-strand, conformation. These results are consistent with the experimental observation that PrP can exist in different conformational states and with structural predictions based on biological data and theoretical modeling that suggest that H1 may play a key role in the conformational transition involved in the development of prion diseases.

}, keywords = {alpha-helices}, isbn = {0961-8368}, url = {://WOS:A1996VA13800019}, author = {Heller, J. and Kolbert, A. C. and Larsen, R. and Ernst, M. and Bekker, T. and Baldwin, M. and Prusiner, S. B. and Pines, A. and Wemmer, D. E.} } @inbook {436, title = {Synthetic Peptides Model α - Helix - β - Sheet Conformational Changes in the Prion Protien}, booktitle = {Peptides: Chemistry, Structure and Biology}, year = {1996}, pages = {468-470}, publisher = {Mayflower Scientific Ltd.}, organization = {Mayflower Scientific Ltd.}, author = {Baldwin, M.A. and Zhang, H. and Bekker, T. and Zhou, S. and Nguyen, J. and Kolbert, A.C. and Heller, J. and James, T.L. and Wemmer, D.E. and Pines, A. and Cohen, F.E. and Prusiner, S.B.}, editor = {Hidges, Pravin T.P Kaumaya and Robert S.} } @article {435, title = {Triple-quantum two-dimensional Al-27 magic-angle spinning nuclear magnetic resonance spectroscopic study of aluminosilicate and aluminate crystals and glasses}, journal = {Journal of the American Chemical Society}, volume = {118}, year = {1996}, note = {J Am Chem SocVa026Times Cited:139Cited References Count:31}, month = {Jul 31}, pages = {7209-7214}, abstract = {

A new two-dimensional magic-angle spinning NMR experiment(1,2) using multiple-quantum coherences of half-integer quadrupolar nuclei was used to study Al-27 sites in crystalline samples of leucite (KAlSi2O6), anorthite (CaAl2Si2O8), and kyanite (Al2SiO5), as well as CaAl2Si2O8 glass and a magnesium aluminoborate glass. In the crystals, multiple sites are partially resolved and new results for isotropic chemical shifts and quadrupolar parameters are derived, using data collected at a single magnetic field. Data for both leucite and anorthite are consistent with previous results that correlate chemical shifts with mean intertetrahedral bond angle. Signal can be obtained from sites with quadrupolar coupling constants as large as 9 MHz, but intensities are reduced. In the aluminoborate glass, peaks for sites with different Al coordination numbers are well separated. The lack of such features in CaAl2Si2O8 glass rules out the presence of significant quantities of AlO5 and AlO6 groups.

}, keywords = {anorthite}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja9606586}, url = {://WOS:A1996VA02600027}, author = {Baltisberger, J. H. and Xu, Z. and Stebbins, J. F. and Wang, S. H. and Pines, A.} } @article {443, title = {Adsorption Properties of Porous Silicon Characterized by Optically Enhanced Xe-129 Nmr-Spectroscopy}, journal = {Surface Science}, volume = {334}, year = {1995}, note = {Surf SciRk973Times Cited:31Cited References Count:33}, month = {Jul 10}, pages = {L730-L734}, abstract = {

Highly spin polarized xenon is used to study the adsorption properties of porous silicon surfaces by Xe-129 NMR spectroscopy. The sensitivity enhancement through optical pumping allows the NMR characterization of small amounts of physisorbed xenon in a pressure regime typical for adsorption isotherms. Fully hydrogen terminated porous silicon, porous silicon with an increased number of dangling bonds and porous silicon after methanol adsorption are characterized by the adsorbed Xe-129 NMR lineshape, chemical shift and relaxation behavior.

}, keywords = {field}, isbn = {0039-6028}, doi = {Doi 10.1016/0039-6028(95)80024-7}, url = {://WOS:A1995RK97300007}, author = {Pietrass, T. and Bifone, A. and Pines, A.} } @article {450, title = {Berry dephasing due to diffusion in nuclear quadrupole resonance}, journal = {Chemical Physics Letters}, volume = {247}, year = {1995}, note = {Chem Phys LettTl671Times Cited:4Cited References Count:19}, month = {Dec 22}, pages = {215-220}, abstract = {

Berry\&$\#$39;s phase can give rise to coherence dephasing in optically detected nuclear quadrupole resonance of gaseous Xe-131. Diffusion of xenon atoms around a toroidal container should cause incoherent acquisition of Berry\&$\#$39;s phase, with consequent loss of phase coherence between atoms. This leads to signal loss which is equivalent to spin relaxation. The rate of dephasing is calculated by two different methods: first, using an exact treatment of diffusion, and secondly, using average propagators. Berry dephasing is predicted to be an important relaxation mechanism in this system.

}, keywords = {nmr}, isbn = {0009-2614}, doi = {Doi 10.1016/0009-2614(95)01218-8}, url = {://WOS:A1995TL67100004}, author = {Jones, J. A. and Pines, A.} } @article {449, title = {C-13 Chemical-Shift Tensor Correlation Via Spin-Diffusion in Solid Tropolone Using Switched-Angle Spinning Spectroscopy}, journal = {Journal of Chemical Physics}, volume = {103}, year = {1995}, note = {J Chem PhysTh657Times Cited:7Cited References Count:42}, month = {Dec 8}, pages = {9844-9854}, abstract = {

In switched-angle spinning spectroscopy (SAS) a sample is spun about different angles, beta, relative to the magnetic field, during various periods of the experiment. In the present work, SAS is combined with two-dimensional exchange spectroscopy in order to correlate carbon-13 chemical shift tensors of the carbonyl (1) and hydroxyl (2) carbons of tropolone. Experiments were performed on a sample enriched to 25 at. \% in each of these sites (at different molecules). At this level of enrichment the dominant exchange mechanism between the two sites involves spin diffusion, The experiment consists of a preparation period during which the sample spins at the magic angle and the magnetization of one of the sites is quenched by means of a selective pulse sequence. During the rest of the experiment the sample spins with its axis away from the magic angle except for a short period just before the detection where the axis is switched to the magic angle in order to select the magnetization to be detected. Experiments were performed for all four possible combinations of the initial and final magnetizations, thus providing chemical shift correlations between carbons 1,1\&$\#$39;,2, and 2\&$\#$39; in the two magnetically inequivalent (but symmetry related) molecules in the unit cell. Combining these results with the known crystal structure of tropolone (neglecting a small tilt between the perpendicular to the molecular plane and the crystallographic c-axis) provides information on the orientation and magnitude of the chemical shift tensors of the two types of carbons, The principal values (in ppm) are sigma(xx)(1)=65, sigma(yy)(1)=33, sigma(zz)(1)=-98, sigma(xx)(2)=77, sigma(yy)(2)=17, and sigma(zz)(2)=-94. Assuming sigma(zz) to be perpendicular to the molecular plane, the orientations of the sigma(yy) s\&$\#$39; are 12 degrees off the C-1=0 bond (toward the hydroxyl carbon) for carbon 1 and 10 degrees off the C-3=C-2 bond (away from the carbonyl carbon) for carbon 2. (C) 1995 American Institute of Physics.

}, keywords = {spectra}, isbn = {0021-9606}, doi = {Doi 10.1063/1.469951}, url = {://WOS:A1995TH65700040}, author = {Larsen, R. G. and Lee, Y. K. and He, B. and Yang, J. O. and Luz, Z. and Zimmermann, H. and Pines, A.} } @article {446, title = {Coherent Isotropic Averaging in Zero-Field Nuclear-Magnetic-Resonance .2. Cubic Sequences and Time-Reversal of Spin Couplings}, journal = {Journal of Chemical Physics}, volume = {103}, year = {1995}, note = {J Chem PhysRu109Times Cited:8Cited References Count:35}, month = {Sep 8}, pages = {3982-3997}, abstract = {

We present a special case of the theory of coherent isotropic averaging in zero-field NMR, given in part I of this work. In a zero external field, combinations of the magnetic-field pulses restricted to pi/2 rotations along the three coordinate axes can selectively average internal spin Hamiltonians while preserving the intrinsic invariance of the spectrum with respect to the sample orientation. Compared with the general case, the limits of the allowed scaling factors of first- and second-rank interactions are slightly reduced. For instance, time reversal is possible for second-rank tensors with a -1/5 scaling factor, instead of -1/4 in general. Finite pulse compensations are analyzed and experimental illustrations are given for two optimum time-reversal sequences. The cubic sequences, though less efficient than the icosahedral sequences, are technically more feasible and may be used in zero-field experiments such as decoupling (by rank or nuclear species), time reversal or multipolar experiments (the zero-field equivalent of multiple-quantum NMR). (C) 1995 American Institute of Physics.

}, keywords = {nqr}, isbn = {0021-9606}, doi = {Doi 10.1063/1.469585}, url = {://WOS:A1995RU10900012}, author = {Llor, A. and Olejniczak, Z. and Pines, A.} } @article {447, title = {Coherent Isotropic Averaging in Zero-Field Nuclear-Magnetic-Resonance .1. General-Theory and Icosahedral Sequences}, journal = {Journal of Chemical Physics}, volume = {103}, year = {1995}, note = {J Chem PhysRu109Times Cited:9Cited References Count:59}, month = {Sep 8}, pages = {3966-3981}, abstract = {

We present a general theory of coherent isotropic averaging in nuclear magnetic resonance (NMR). In a zero external field, magnetic-field pulses can selectively average the internal spin Hamiltonians, while preserving the intrinsic invariance of the spectrum with respect to the sample orientation. The theory predicts the limits of the scaling factors for tenser interactions of different ranks. Time reversal is found to be possible for first- and second-rank tensors with scaling factors of -1/3 and -1/4, respectively. Explicit sequences, based on icosahedral symmetry, are given for a number of optimal scaling factors. To illustrate the theory, an experiment is also presented in the special case of rank-selective decoupling. As in high-field NMR, applications can be expected from the introduction of coherent averaging schemes for zero-held techniques: for example, decouplings (by rank or nuclear species), time reversal, and multipolar experiments (zero-field analog of multiple-quantum NMR). (C) 1995 American Institute of Physics.

}, keywords = {couplings}, isbn = {0021-9606}, doi = {Doi 10.1063/1.469584}, url = {://WOS:A1995RU10900011}, author = {Llor, A. and Olejniczak, Z. and Pines, A.} } @article {437, title = {Detection of N-14 and CL-35 in Cocaine Base and Hydrochloride Using NQR, NMR and SQUID Techniques}, journal = {Analytical Chemistry}, year = {1995}, pages = {2256-2263}, author = {Yesinowski, J.Y. and Buess, M.L. and Garroway, A.N. and Zeigeweid, M. and Pines, A.} } @article {453, title = {High-Field Cross-Polarization Nmr from Laser-Polarized Xenon to Surface Nuclei}, journal = {Applied Magnetic Resonance}, volume = {8}, year = {1995}, note = {Appl Magn ResonRt202Times Cited:30Cited References Count:17}, pages = {373-384}, abstract = {

A method for NMR investigations of surface nuclei using cross polarization from optically polarized xenon (OPCP) is described. We find this methodology results in enhancement factors of approximately 10(3) upon application to surface protons. The dynamics of Xe-129 transfer to protons is examined in some detail, including the time, temperature, and multiple contact dependences of signal intensities. Furthermore, we discuss the sensitivity of the transfer process to spatial diffusion. Finally, we report on application of the OPCP experiment to a low total surface area sample.

}, keywords = {gel}, isbn = {0937-9347}, url = {://WOS:A1995RT20200005}, author = {Gaede, H. C. and Song, Y. Q. and Taylor, R. E. and Munson, E. J. and Reimer, J. A. and Pines, A.} } @article {448, title = {Linear Prediction with Singular-Value Decomposition for Removing Phase Artifacts in 2d Vacsy Spectra}, journal = {Journal of Magnetic Resonance Series A}, volume = {112}, year = {1995}, note = {J Magn Reson Ser AQd079Times Cited:8Cited References Count:20}, month = {Jan}, pages = {112-117}, keywords = {signals}, isbn = {1064-1858}, doi = {Doi 10.1006/Jmra.1995.1018}, url = {://WOS:A1995QD07900018}, author = {Lee, Y. K. and Vold, R. L. and Hoatson, G. L. and Lin, Y. Y. and Pines, A.} } @article {444, title = {Low-Power Decoupling Sequences for High-Resolution Chemical-Shift and Local-Field Nmr-Spectra of Liquid-Crystals}, journal = {Journal of Magnetic Resonance Series A}, volume = {113}, year = {1995}, note = {J Magn Reson Ser AQw158Times Cited:11Cited References Count:29}, month = {Apr}, pages = {169-176}, abstract = {

Various new and well-established multiple-pulse sequences that provide homonuclear dipolar decoupling are compared on a high-resolution spectrometer/probe configuration using low RF-irradiation powers. Proton-proton decoupled carbon-13 spectra of singly C-13-labeled benzene dissolved in a nematic liquid crystal and of the liquid crystal 152 are presented. Two classes of multiple-pulse sequences are studied that produce either broadband decoupled carbon spectra or separated local-held spectra. Several new approaches for the design of windowless sequences are demonstrated to be valuable in these heteronuclear experiments. They include implementations of the iterative MLEV scheme and the use of 270 degrees pulses. Furthermore, noncyclic propagators have been found that exhibit advantages over closely related cyclic analogues in both classes of decoupling sequences. (C) 1995 Academic Press, Inc.

}, keywords = {dipolar}, isbn = {1064-1858}, doi = {Doi 10.1006/Jmra.1995.1077}, url = {://WOS:A1995QW15800005}, author = {Nanz, D. and Ernst, M. and Hong, M. and Ziegeweid, M. A. and Schmidt-Rohr, K. and Pines, A.} } @article {441, title = {Magnetic-Resonance Evidence for Metallic State in Highly Conducting Polyaniline}, journal = {Synthetic Metals}, volume = {69}, year = {1995}, note = {Synthetic MetQl601Times Cited:9Cited References Count:12}, month = {Mar 1}, pages = {243-244}, abstract = {

Polyaniline doped with camphor sulfonic acid (PANI-CSA) has been shown to yield a material which, after processing from solutions in meta-cresol, exhibit a temperature independent magnetic susceptibility down to 50K. Below 50K a Curie like contribution sets in. We also report C-13 NMR experiments which clearly show that the C-13 spin lattice relaxation rates obey the Korringa relation for relaxation via the hyperfine coupling to conduction electrons.

}, keywords = {polymers}, isbn = {0379-6779}, doi = {Doi 10.1016/0379-6779(94)02435-2}, url = {://WOS:A1995QL60100097}, author = {Sariciftci, N. S. and Kolbert, A. C. and Cao, Y. and Heeger, A. J. and Pines, A.} } @article {442, title = {Monitoring Xenon Clathrate Hydrate Formation on Ice Surfaces with Optically Enhanced Xe-129 Nmr}, journal = {Journal of the American Chemical Society}, volume = {117}, year = {1995}, note = {J Am Chem SocRk426Times Cited:60Cited References Count:41}, month = {Jul 19}, pages = {7520-7525}, abstract = {

A new technique for monitoring the formation of xenon clathrate hydrates is presented. Under controlled-temperature conditions, clathrate formation is studied with optically enhanced Xe-129 NMR spectroscopy, which allows the observation of the xenon occupation of both small and large clathrate cages. The experiments were performed in a temperature range of 170 to 258 K. Only in the range of 195 to 233 K did clathrate formation occur, with applied pressures of typically 0.3 MPa. The NMR data are analyzed with a simple kinetic model, which provides a rate coefficient for clathrate formation and a time constant which describes the decay of the NMR signal intensity. The analysis of the rate coefficients and occupancy ratios of the large to the small cages under the different experimental conditions enabled us to obtain some novel information on the hydrate phase formed on ice surfaces. The results suggest that the surface phase formed initially has many more occupied small cages than the bulk phase at equilibrium and that the composition evolves toward that of the bulk phase in a few minutes. At higher temperatures (258 K) the surface phase seems to be less stable than the bulk phase.

}, keywords = {field}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja00133a025}, url = {://WOS:A1995RK42600025}, author = {Pietrass, T. and Gaede, H. C. and Bifone, A. and Pines, A. and Ripmeester, J. A.} } @article {451, title = {Nmr Measurement of Signs and Magnitudes of C-H Dipolar Couplings in Lecithin}, journal = {Journal of the American Chemical Society}, volume = {117}, year = {1995}, note = {J Am Chem SocQn458Times Cited:45Cited References Count:25}, month = {Mar 22}, pages = {3310-3311}, keywords = {orientation}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja00116a051}, url = {://WOS:A1995QN45800051}, author = {Hong, M. and Schmidt-Rohr, K. and Pines, A.} } @article {440, title = {Orientation and Motion of Tetrahydrofuran in Graphite-Intercalation Compounds - Proton Nmr-Studies of Cs(Thf)(1.3)C-24 and K(Thf)(2.5)C-24}, journal = {Journal of Physical Chemistry}, volume = {99}, year = {1995}, note = {J Phys Chem-UsRg562Times Cited:5Cited References Count:31}, month = {Jun 29}, pages = {10565-10572}, abstract = {

The orientation and motion of tetrahydrofuran (THF) in the ternary graphite intercalation compounds Cs-(THF)(1.3)C-24 and K(THF)(2.5)C-24 have been studied by proton NMR. Simulations of the NMR spectra indicate that the THF molecules in CS(THF)(1.3)C-24 have their mean planes oriented parallel to the layers of the host lattice, while the THF molecules in K(THF)(2.5)C-24 have their mean planes oriented at an angle between 50 degrees and 75 degrees from the graphite layers. The proton NMR spectra of both compounds show evidence that the THF molecules rotate about the normal to the graphite layers and confirm X-ray diffraction studies showing a degree of orientational disorder in the samples, corresponding to a mosaic spread in the graphite layer orientation. The conformation of the intercalated THF was studied by simulating the experimental NMR spectra using models for the conformational motion of THF. Simulations indicate that the conformation of intercalated THF is different than gas or liquid phase THF, which has been found to have a ring puckering amplitude of 0.38-0.44 Angstrom and to undergo nearly free pseudorotation through a series of conformations. Best agreement between simulated and experimental NMR spectra of Cs(THF)(1.3)C-24 was Obtained with THF interconverting between two conformations of C-s symmetry and a puckering amplitude of 0.30 Angstrom. Free or slightly hindered pseudorotation of THF (observed in liquid or gaseous THF) in this compound produces simulated spectra that differ significantly from the experimental spectra. Simulated proton NMR spectra of K(THF)(2.5)C-24 using conformations of C-s symmetry or free or slightly hindered pseudorotation of THF do not fit the experimental spectra sufficiently well to allow distinction between the conformational motions or to exclude other possible motions.

}, keywords = {system}, isbn = {0022-3654}, doi = {Doi 10.1021/J100026a020}, url = {://WOS:A1995RG56200020}, author = {Schmidt, C. and Rosen, M. E. and Caplan, D. F. and Pines, A. and Quinton, M. F.} } @article {452, title = {Solid-State O-17 Magic-Angle and Dynamic-Angle Spinning Nmr-Study of the Sio2 Polymorph Coesite}, journal = {Journal of Physical Chemistry}, volume = {99}, year = {1995}, note = {J Phys Chem-UsRn706Times Cited:95Cited References Count:41}, month = {Aug 10}, pages = {12341-12348}, abstract = {

Five distinctly resolved O-17 solid-state NMR resonances in room temperature coesite, an SiO2 polymorph, have been observed and assigned using dynamic-angle spinning (DAS) at 11.7 T along with magic-angle spinning (MAS) spectra at 9.4 and 11.7 T. The O-17 quadrupolar parameters for each of the five oxygen environments in coesite are correlated with the Si-O-Si bridging bond angles determined by diffraction experiments. The sign of e(2)qQ/h along with the orientation of the electric field gradient for oxygen in the Si-O-Si linkage were determined from a Townes-Dailey analysis of the data.

}, keywords = {oxygen}, isbn = {0022-3654}, doi = {Doi 10.1021/J100032a045}, url = {://WOS:A1995RN70600045}, author = {Grandinetti, P. J. and Baltisberger, J. H. and Farnan, I. and Stebbins, J. F. and Werner, U. and Pines, A.} } @article {439, title = {Spin-Polarized Xe-129 Gas Imaging of Materials}, journal = {Journal of Magnetic Resonance Series A}, volume = {115}, year = {1995}, note = {J Magn Reson Ser ARl474Times Cited:49Cited References Count:23}, month = {Jul}, pages = {127-130}, keywords = {xenon}, isbn = {1064-1858}, doi = {Doi 10.1006/Jmra.1995.1157}, url = {://WOS:A1995RL47400017}, author = {Song, Y. Q. and Gaede, H. C. and Pietrass, T. and Barrall, G. A. and Chingas, G. C. and Ayers, M. R. and Pines, A.} } @article {454, title = {Surface Study of Supported Metal Particles by Xe-129 Nmr}, journal = {Physical Review Letters}, volume = {74}, year = {1995}, note = {Phys Rev LettQt449Times Cited:21Cited References Count:26}, month = {Apr 17}, pages = {3277-3280}, keywords = {states}, isbn = {0031-9007}, doi = {Doi 10.1103/Physrevlett.74.3277}, url = {://WOS:A1995QT44900047}, author = {Bifone, A. and Pietrass, T. and Kritzenberger, J. and Pines, A. and Chmelka, B. F.} } @article {438, title = {Xe-129 Nmr-Studies of Hyper-Cross-Linked Polyarylcarbinols - Rigid Versus Flexible Structures}, journal = {Chemistry of Materials}, volume = {7}, year = {1995}, note = {Chem MaterRk993Times Cited:27Cited References Count:30}, month = {Jul}, pages = {1325-1332}, abstract = {

Xenon NMR is used with adsorption measurements to infer information about the microstructure of some novel hyper-cross-linked polyarylcarbinols. It is shown that rigidrod connecting units are necessary for microporosity in these systems, as hyper-cross-linked polymers based on flexible structures are found to have conventional surface areas and xenon NMR spectra. A microporous polymer based on rigid triarylcarbinol monomers shows high xenon uptake and a linear chemical shift variation with pressure at room temperature. Spin-lattice relaxation and cross-polarization dynamics are studied at low temperatures. In this regime the xenon has extremely long equilibration times, and the adsorption dynamics are complicated but give important insight into the polymer topology. The data are compared with two possible models of the polymer microstructwre.

}, keywords = {adsorption}, isbn = {0897-4756}, doi = {Doi 10.1021/Cm00055a008}, url = {://WOS:A1995RK99300008}, author = {Urban, C. and Mccord, E. F. and Webster, O. W. and Abrams, L. and Long, H. W. and Gaede, H. and Tang, P. and Pines, A.} } @article {445, title = {Xenon Nmr-Study of a Nematic Liquid-Crystal Confined to Cylindrical Submicron Cavities}, journal = {Journal of Physical Chemistry}, volume = {99}, year = {1995}, note = {J Phys Chem-UsRm901Times Cited:17Cited References Count:37}, month = {Aug 3}, pages = {11989-11993}, abstract = {

NMR studies of xenon gas dissolved in the liquid crystal ZLI 1132 confined to submicron cylindrical cavities are reported. Spectra taken as a function of temperature yield a clear indication of the nematic to isotropic phase transition of the confined liquid crystals. In the nematic phase at 21 degrees C, the resonance line of dissolved Xe-129 exhibits a chemical shift anisotropy of 15 ppm due to a random distribution of director axes in the plane perpendicular to the long axis of the cylinder. The anisotropy and temperature dependence of the confined system are compared to control experiments that use the bulk liquid crystal. The quadrupolar splitting observed in the Xe-131 NMR spectrum of the confined liquid crystalline solution of xenon gas is slightly greater than that found in the bulk. Two-dimensional exchange NMR demonstrates that the xenon atoms probe different average liquid crystal directors within a single cavity on a 20 ms time scale and that interpore exchange occurs on a time scale of 400 ms. The exchange data indicate that changes in the orientation of the director within individual cavities occur on a length scale of about 2 mu m.

}, keywords = {mixtures}, isbn = {0022-3654}, doi = {Doi 10.1021/J100031a029}, url = {://WOS:A1995RM90100029}, author = {Long, H. W. and Luzar, M. and Gaede, H. C. and Larsen, R. G. and Kritzenberger, J. and Pines, A. and Crawford, G. P.} } @article {464, title = {2-Dimensional Xe-129 Exchange Nmr Measurements of Xenon Dynamics in Na-a Zeolite}, journal = {Zeolites and Related Microporous Materials: State of the Art 1994}, volume = {84}, year = {1994}, note = {Stud Surf Sci CatalPart a-CBd02eTimes Cited:3Cited References Count:21Studies in Surface Science and Catalysis}, pages = {519-526}, abstract = {Two-dimensional (2D) exchange NMR is a powerful tool for measuring the dynamics and energetics of adsorbed xenon atoms undergoing slow exchange between the alpha-cages of Na-A zeolite. In this proceedings, we present recently published results, as well as additional discussion and data obtained, using 2D Xe-129 NMR to determine rate coefficients for intercage xenon hopping and to correlate them with adsorption and activation energies. Variable-temperature experiments establish the activation energy for hopping between alpha-cages to be 60+/-10 kJ/mol. The dependence of these kinetic and thermodynamic quantities on xenon occupancy of the alpha-cages reflects the importance of intracage interactions on the behavior of the adsorbed guest molecules.}, keywords = {cavities}, isbn = {0167-2991}, url = {://WOS:A1994BD02E00063}, author = {Janicke, M. and Chmelka, B. F. and Larsen, R. G. and Shore, J. and Schmidt-Rohr, K. and Emsley, L. and Long, H. and Pines, A.} } @article {461, title = {3-Dimensional Variable-Angle Nuclear-Magnetic-Resonance Exchange Spectroscopy without Rotor Axis Hopping}, journal = {Journal of Chemical Physics}, volume = {101}, year = {1994}, note = {J Chem PhysNy002Times Cited:12Cited References Count:48}, month = {Aug 1}, pages = {1852-1864}, abstract = {

Slow, large-amplitude chain motions play an important role in determining the macroscopic mechanical properties of polymers. Although such motions have been studied quantitatively by two-dimensional (2D) nuclear: magnetic resonance (NMR) exchange experiments, overlapping anisotropic patterns hamper spectral analysis, and limit applications. Variable angle correlation spectroscopy (VACSY) has proven useful in resolving such problems for rapidly spinning samples by separating anisotropic spectral patterns according to isotropic chemical shifts. In a previous study [J. Am. Chem. Sec. 115, 4825 (1993)], we described a three-dimensional (3D) NMR experiment that incorporates; the VACSY method and a hop of the rotor axis to correlate the isotropic chemical shifts to 2D anisotropic exchange patterns. The hop of the rotor axis, however, presents experimental difficulties and limits the range of motional rates that may be studied. We present in this paper a new 3D VACSY exchange experiment that obtains the same correlations without the need for the rotor axis hop. A series of 2D exchange spectra are recorded with the sample spinning at different rotation axis angles.\&$\#$39; Then using the scaling of the anisotropic frequency at the different angles, we construct the data onto a 3D matrix so that a Fourier transformation directly yields the desired correlations. The technique is applied to C-13 exchange NMR to study the slow molecular motion of ordered isotactic polypropylene.

}, keywords = {distributions}, isbn = {0021-9606}, doi = {Doi 10.1063/1.467696}, url = {://WOS:A1994NY00200011}, author = {Lee, Y. K. and Emsley, L. and Larsen, R. G. and Schmidt-Rohr, K. and Hong, M. and Frydman, L. and Chingas, G. C. and Pines, A.} } @article {465, title = {Cross Polarization and Dynamic-Angle Spinning of O-17 in L-Alanine}, journal = {Bulletin of Magnetic Resonance}, volume = {16}, year = {1994}, pages = {68-72}, author = {Gann, S.L. and Baltisberger, J.H. and Wooten, E.W. and Zimmerman, H. and Pines, A.} } @article {469, title = {Cross-Polarization Dynamic-Angle Spinning Nuclear-Magnetic-Resonance of Quadrupolar Nuclei}, journal = {Molecular Physics}, volume = {81}, year = {1994}, note = {Mol PhysNe628Times Cited:21Cited References Count:29}, month = {Apr 10}, pages = {1109-1124}, abstract = {

The use of variable-angle spinning (VAS) with cross-polarization (CP) for quadrupolar nuclei has been evaluated both experimentally and theoretically. It is known that under normal spinning speeds the best VAS angle for performing CP is 0-degrees (parallel to the magnetic field). We show that, with the use of dynamic-angle spinning (DAS) probes, CP may be done at 0-degrees and detection in a one-dimensional VAS experiment may be performed at any angle in a zero-polarized VAS (ZPVAS) experiment. Finally, the combination of CP with k = 5 DAS (where the sample is spun first at 0-degrees followed by 63.43-degrees) provides both the highest resolution and the greatest sensitivity under normal conditions.

}, keywords = {probe}, isbn = {0026-8976}, doi = {Doi 10.1080/00268979400100741}, url = {://WOS:A1994NE62800007}, author = {Baltisberger, J. H. and Gann, S. L. and Grandinetti, P. J. and Pines, A.} } @inbook {466, title = {Group Theory and Nuclear Magnetic Resonance Dynamics}, booktitle = {NMR and More - In Honour of Anatole Abragam}, year = {1994}, pages = {175-199}, publisher = {Les Editions de Physique}, organization = {Les Editions de Physique}, author = {Emsley, L. and Schmidt-Rohr, K. and Pines, A.}, editor = {Porneuf, M. Goldman and M.} } @article {463, title = {Measurement of Internuclear Distances by Switched Angle Spinning Nmr}, journal = {Journal of Physical Chemistry}, volume = {98}, year = {1994}, note = {J Phys Chem-UsPc619Times Cited:11Cited References Count:20}, month = {Aug 18}, pages = {7936-7938}, abstract = {

Dipolar switched angle spinning, an NMR technique due to Terao et al. [Terao, T.; Miura H.; Saika, A, J. Chem. Phys. 1986, 85, 3816], has been used to measure C-13-C-13 distances in the solid state. The experiment involves rotation of the sample at two different angles during different periods of a two-dimensional experiment. An evolution period with off-magic-angle spinning and chemical shift refocusing, followed by detection of the signal under magic angle spinning, yields scaled Pake patterns in omega(1), correlated with their isotropic shifts in omega(2) allowing the high-resolution measurement of dipolar couplings. We demonstrate this experiment on samples of doubly C-13 labeled zinc acetate and a 14 amino acid peptide, in which we show that under optimal conditions distances of up to 5 Angstrom may be measured.

}, keywords = {protein}, isbn = {0022-3654}, doi = {Doi 10.1021/J100084a003}, url = {://WOS:A1994PC61900003}, author = {Kolbert, A. C. and Grandinetti, P. J. and Baldwin, M. and Prusiner, S. B. and Pines, A.} } @article {459, title = {Multiple-Pulse Nuclear-Magnetic-Resonance of Optically Pumped Xenon in a Low Magnetic-Field}, journal = {Physical Review A}, volume = {50}, year = {1994}, note = {Phys Rev ANx001Times Cited:23Cited References Count:38}, month = {Jul}, pages = {567-574}, abstract = {

Multiple-pulse coherent averaging methods are used to increase the resolution and frequency range of optically pumped xenon NMR in nutation and point-by-point precession experiments. We observe quadrupolar splittings in Xe-131 spectra due to the macroscopic asymmetry of pumping cells similar to those reported previously, but with reduced demands on magnetic-field homogeneity. Cell treatment with hydrogen gas increases the quadrupolar splittings by a factor of 3 over bare Pyrex cells.

}, keywords = {ne-21}, isbn = {1050-2947}, doi = {Doi 10.1103/Physreva.50.567}, url = {://WOS:A1994NX00100070}, author = {Raftery, D. and Long, H. W. and Shykind, D. and Grandinetti, P. J. and Pines, A.} } @article {456, title = {N-14 Squid Nqr of L-Ala-L-His and of Serine}, journal = {Zeitschrift Fur Naturforschung Section a-a Journal of Physical Sciences}, volume = {49}, year = {1994}, note = {Z Naturforsch AQh740Times Cited:2Cited References Count:15}, month = {Dec}, pages = {1188-1192}, abstract = {N-14 nuclear quadrupole resonance spectroscopy, detected with a Superconducting Quantum Interference Device, makes possible the study of nitrogen environments in amino acids and small peptides. The present experiments characterize: 1) the effects of intermolecular interactions upon the amino nitrogen of serine upon cocrystallization of the stereoisomers in a range of concentrations; 2) the changes of the amino and imidazole nitrogen environments brought about by combining L-Alanine and L-Histidine into the dipeptide L-Ala-L-His.}, keywords = {n-14}, isbn = {0932-0784}, url = {://WOS:A1994QH74000013}, author = {Wernerzwanziger, U. and Ziegeweid, M. and Black, B. and Pines, A.} } @article {458, title = {Nmr Measurement of Resolved Heteronuclear Dipole Couplings in Liquid-Crystals and Lipids}, journal = {Journal of Physical Chemistry}, volume = {98}, year = {1994}, note = {J Phys Chem-UsNw531Times Cited:68Cited References Count:25}, month = {Jul 7}, pages = {6668-6670}, abstract = {

Simplified nuclear magnetic resonance (NMR) spectra of heteronuclear dipolar couplings for molecules in an anisotropic environment, such as liquid crystals and lipids, are obtained by proton-detected local-field spectroscopy. The distance-dependent dipolar interactions between spins of magnetically active nuclei can be determined directly from the spectrum because many-body effects that complicate conventional dipolar NMR spectra are avoided by selectively probing local fields produced by rare spins at the location of abundant spins. We employ the technique to resolve the carbon-proton dipolar couplings of benzene dissolved in a nematic liquid crystal and to measure phosphorus-proton couplings in lecithin in the L(alpha) phase to obtain constraints on the phosphocholine headgroup structure.

}, keywords = {solids}, isbn = {0022-3654}, doi = {Doi 10.1021/J100078a002}, url = {://WOS:A1994NW53100002}, author = {Schmidt-Rohr, K. and Nanz, D. and Emsley, L. and Pines, A.} } @book {468, title = {NMR techniques in catalysis}, series = {Chemical industries}, year = {1994}, note = {93043400GLADN151159362edited by Alexis T. Bell, Alexander Pines.ill. ; 24 cm.Includes bibliographical references and index.Chemical industries ; v. 55.}, pages = {viii, 432 p.}, publisher = {M. Dekker}, organization = {M. Dekker}, address = {New York}, keywords = {Nuclear magnetic resonance spectroscopy.}, isbn = {0824791738 (acid-free)}, author = {Bell, A.T. and Pines, A.} } @article {467, title = {Probing Cds Nanocrystal Surfaces with Laser-Polarized Xenon}, journal = {Journal of Physical Chemistry}, volume = {98}, year = {1994}, note = {J Phys Chem-UsPh559Times Cited:32Cited References Count:29}, month = {Sep 22}, pages = {9400-9404}, abstract = {

This paper describes the application of optically pumped xenon NMR to probe the surface of semiconductor nanocrystals by physisorption at 123 K. These experiments were made possible by using highly spin ordered Xe-129, prepared by optical pumping and spin exchange of a rubidium xenon gas mixture, to increase the NMR signal strength. CdS nanocrystals were prepared by regulated growth in inverse micelles and precipitated by surface derivatization with thiophenol. Nanocrystals of 11.8, 12.8, and 23 Angstrom radii with 26\%, 63\%, and 57\% thiophenol surface coverage, respectively, were characterized. Within this sample parameter space, the Xe-129 spectra, recorded at varying xenon coverages, depended strongly on thiophenol surface coverage but were not sensitive to the crystallite size. In addition, the nanocrystals with low thiophenol coverage yielded a xenon line shape consisting of two components, interpreted as xenon signals arising from distinct surface domains. These domains are presumably formed by the aggregation of thiophenol molecules on the nanocrystal surface when the thiophenol coverage is incomplete, a model which is consistent with existing X-ray photoelectron spectroscopy and liquid state H-1 NMR data.

}, keywords = {resonance}, isbn = {0022-3654}, doi = {Doi 10.1021/J100089a008}, url = {://WOS:A1994PH55900008}, author = {Bowers, C. R. and Pietrass, T. and Barash, E. and Pines, A. and Grubbs, R. K. and Alivisatos, A. P.} } @book {481, title = {Proceedings of the International School of Physics Enrico Fermi, Course CXXIII 1992}, series = {Lectures in Pulsed NMR}, year = {1994}, publisher = {World Scientific}, organization = {World Scientific}, edition = {2nd}, chapter = {123-266}, author = {Emsley, L. and Pines, A.} } @article {455, title = {SQUID-NQR of N-14}, journal = {NQI Newsletter}, volume = {3}, year = {1994}, pages = {24-25}, author = {Ziegeweid, M. and Werner, U. and Black, B. and Pines, A.} } @article {457, title = {Theory and Exact-Solutions for Tyckos Zero-Field Nmr in High-Field}, journal = {Journal of Magnetic Resonance Series A}, volume = {109}, year = {1994}, note = {J Magn Reson Ser APb546Times Cited:5Cited References Count:27}, month = {Aug}, pages = {157-165}, abstract = {

A theory of zero-field NMR in high field (ZFHF-NMR) is described in terms of coherent averaging and irreducible tensors. The theory is used to determine analytical solutions for the parameters of the trajectory proposed and used by Tycko. A new pulse sequence is presented, and optimized solutions for dynamic-angle spinning, dynamic-angle hopping, and double-rotation versions of ZFHF-NMR are discussed. (C) 1994 Academic Press, Inc.

}, keywords = {solid-state nmr}, isbn = {1064-1858}, doi = {Doi 10.1006/Jmra.1994.1149}, url = {://WOS:A1994PB54600003}, author = {Sun, B. Q. and Pines, A.} } @article {462, title = {Xe-129 Nmr-Study of Tio2 (Anatase)-Supported V2o5 Catalysts}, journal = {Journal of Physical Chemistry}, volume = {98}, year = {1994}, note = {J Phys Chem-UsPk740Times Cited:19Cited References Count:61}, month = {Oct 6}, pages = {10173-10179}, abstract = {

TiO2 (anatase), V2O5, and V2O5/TiO2 (anatase) catalysts with 1.3\%, 3.0\%, and 9.8\% weight loadings of V2O5 have been studied using temperature-dependent xenon-129 NMR spectroscopy. The intrinsic chemical shift values due to the interaction of xenon with the surface are 109 +/- 3 ppm for TiO2 (anatase) and 93 +/- 5 ppm for V2O5. The V2O5/TiO2 catalysts provide strong adsorption sites for xenon which cause an initial decrease of the chemical shift values at low xenon loadings. Additionally, the spectra of pure V2O5 reveal two distinct environments for the xenon atoms, consistent with the hysteresis of the isotherm and the existence of pores. Two-dimensional exchange spectroscopy was used to measure the rates and activation energy of xenon moving between these two environments.

}, keywords = {nay zeolite}, isbn = {0022-3654}, doi = {Doi 10.1021/J100091a037}, url = {://WOS:A1994PK74000037}, author = {Kritzenberger, J. and Gaede, H. C. and Shore, J. S. and Pines, A. and Bell, A. T.} } @proceedings {460, title = {Yakir Aharonov: From A to B}, journal = {Proc. of the Int. Conf. on Fundamental Aspects of Quantum Theory}, year = {1994}, publisher = {World Scientific}, author = {Pines, A.}, editor = {Anandan, J. and Safko, J.} } @article {473, title = {2-Dimensional Proton Nmr-Studies of the Conformations and Orientations of N-Alkanes in a Liquid-Crystal Solvent}, journal = {Journal of Physical Chemistry}, volume = {97}, year = {1993}, note = {J Phys Chem-UsKx596Times Cited:37Cited References Count:20}, month = {Apr 15}, pages = {3858-3866}, abstract = {

Magnetic dipole couplings between pairs of protons in a series of n-alkanes (hexane through decane) dissolved in a nematic liquid crystal were measured by two-dimensional NMR spectroscopy. The dependence of dipole couplings on the distance between pairs of protons and on the orientation of the molecule with respect to the applied magnetic field make them a potentially rich source of information about molecular conformation and orientation. Interpretation of the dipole couplings, however, is complicated by the fact that the measured couplings are averaged over all molecular conformations and orientations sampled by the molecule. Thus, the couplings do not directly provide internuclear distances and orientations, but instead provide constraints on the time-averaged conformations and orientations of the n-alkane molecules that can be used as a rigorous test of models for intermolecular interactions in liquid crystals. Three models for solute-liquid crystal interactions were examined; the model proposed by Photinos et al.1 was found to be superior to the others in describing this system. The results of the modeling, including order parameters and conformer probabilities for the alkanes, are discussed and compared to n-alkanes in the liquid state.

}, keywords = {size}, isbn = {0022-3654}, doi = {Doi 10.1021/J100117a037}, url = {://WOS:A1993KX59600037}, author = {Rosen, M. E. and Rucker, S. P. and Schmidt, C. and Pines, A.} } @article {472, title = {An Approximate Method of Side-Band Intensity Calculation in Magic-Angle-Spinning Nmr}, journal = {Applied Magnetic Resonance}, volume = {5}, year = {1993}, note = {Appl Magn ResonLv192Times Cited:2Cited References Count:19}, pages = {43-61}, abstract = {

A theory of sideband intensity is derived by expanding into a Taylor series the free induction decay observed under magic angle spinning (MAS). According to this procedure, the free induction decay signal is completely represented by a basis of irreducible tensors from rank zero to rank infinity. After averaging over all orientations, only the zero-order irreducible tensors contribute to the sideband intensities. Symmetry properties of the sidebands can be seen clearly in this expansion, and an approximate formula up to ninth order is obtained by truncating the series. Sideband intensities can be calculated rapidly with this formula. The results agree satisfactorily with the exact sideband intensities obtained by numerical simulation if the ratio of the anisotropy to the spinning speed, omega0delta/omega(r), is smaller than 3. The relationship of the sideband intensities with the moments of a MAS spectrum shows that the proposed method is an alternative to moment analysis when the spinning speed is not very slow. Anisotropic information about the chemical shift anisotropy interaction therefore can be extracted efficiently from experimental spectra by this approximate method.

}, keywords = {nuclei}, isbn = {0937-9347}, url = {://WOS:A1993LV19200006}, author = {Sun, B. Q. and Pines, A.} } @article {482, title = {Cross Polarization from Laser-Polarized Solid Xenon to (Co2)-C-13 by Low-Field Thermal Mixing}, journal = {Chemical Physics Letters}, volume = {205}, year = {1993}, note = {Chem Phys LettKv519Times Cited:61Cited References Count:11}, month = {Apr 9}, pages = {168-170}, abstract = {

The first observation of nuclear spin polarization enhancement in a molecular species by coupling to laser-polarized xenon is reported. The spins of (CO2)-C-13 were cooled by inclusion into the xenon solid followed by thermal mixing in magnetic fields comparable to the heteronuclear dipolar interactions. High-field NMR detection yielded enhancement factors of up to 200. Moreover, a change in the sense of the helicity of the optical pumping light results in a sign reversal of the spin temperature and hence an inversion of the C-13 NMR signal.

}, keywords = {nmr}, isbn = {0009-2614}, doi = {Doi 10.1016/0009-2614(93)89223-5}, url = {://WOS:A1993KV51900008}, author = {Bowers, C. R. and Long, H. W. and Pietrass, T. and Gaede, H. C. and Pines, A.} } @article {479, title = {Dynamic-Angle Spinning without Side-Band}, journal = {Chemical Physics Letters}, volume = {210}, year = {1993}, note = {Chem Phys LettLp038Times Cited:18Cited References Count:16}, month = {Jul 30}, pages = {405-410}, abstract = {

By means of rotor-synchronized pi-pulses, it is possible to eliminate the spinning sidebands (while retaining their full intensity in the isotropic centerband) that usually arise in dynamic-angle spinning (DAS) NMR. The theory of this approach, dynamic-angle hopping (DAH-180), is described and illustrated with experimental results on quadrupolar nuclei. A magic-angle hopping (MAH-180) version of magic-angle spinning is also possible and can be used in a two-dimensional NMR experiment to produce sideband-free isotropic-anisotropic correlation spectra for spin-1/2 nuclei.

}, keywords = {resolution}, isbn = {0009-2614}, doi = {Doi 10.1016/0009-2614(93)87045-5}, url = {://WOS:A1993LP03800018}, author = {Gann, S. L. and Baltisberger, J. H. and Pines, A.} } @article {470, title = {Effects of Double Rotation on Homonuclear Spin Systems}, journal = {Journal of Magnetic Resonance Series A}, volume = {102}, year = {1993}, note = {J Magn Reson Ser AKz354Times Cited:3Cited References Count:13}, month = {Mar}, pages = {29-33}, keywords = {solids}, isbn = {1064-1858}, doi = {Doi 10.1006/Jmra.1993.1064}, url = {://WOS:A1993KZ35400005}, author = {Wu, Y. and Peng, Z. Y. and Olejniczak, Z. and Sun, B. Q. and Pines, A.} } @article {475, title = {High-Field Cross-Polarization Nmr from Laser-Polarized Xenon to a Polymer Surface}, journal = {Journal of the American Chemical Society}, volume = {115}, year = {1993}, note = {J Am Chem SocLx752Times Cited:77Cited References Count:16}, month = {Sep 8}, pages = {8491-8492}, keywords = {gas}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja00071a086}, url = {://WOS:A1993LX75200086}, author = {Long, H. W. and Gaede, H. C. and Shore, J. and Reven, L. and Bowers, C. R. and Kritzenberger, J. and Pietrass, T. and Pines, A. and Tang, P. and Reimer, J. A.} } @article {476, title = {Nmr-Study of Xenon Dynamics and Energetics in Na-a Zeolite}, journal = {Chemical Physics Letters}, volume = {214}, year = {1993}, note = {Chem Phys LettMd614Times Cited:56Cited References Count:22}, month = {Oct 29}, pages = {220-226}, abstract = {

For xenon atoms adsorbed in Na-A zeolite, electronic interactions cause shifts in NMR frequencies, resulting in a spectrum with discrete peaks from xenon atoms in cages with different xenon occupancies. Using two-dimensional exchange NMR, it is possible to determine the microscopic rates of intercage motion and to relate them to the adsorption and activation energies of the xenon atoms. The dependence of the adsorption energies on xenon cage occupancy reflects the importance of the intercage interactions and is directly related to the cage occupancy distribution. Variable temperature measurements yield an activation energy of about 60 kJ/mol for the transfer of a xenon from one cage to another.

}, keywords = {xe}, isbn = {0009-2614}, doi = {Doi 10.1016/0009-2614(93)90085-F}, url = {://WOS:A1993MD61400015}, author = {Larsen, R. G. and Shore, J. and Schmidt-Rohr, K. and Emsley, L. and Long, H. and Pines, A. and Janicke, M. and Chmelka, B. F.} } @article {478, title = {Pure-Absorption-Mode Lineshapes and Sensitivity in 2-Dimensional Dynamic-Angle Spinning Nmr}, journal = {Journal of Magnetic Resonance Series A}, volume = {103}, year = {1993}, note = {J Magn Reson Ser ALj625Times Cited:98Cited References Count:20}, month = {Jun 1}, pages = {72-81}, keywords = {nuclei}, isbn = {1064-1858}, doi = {Doi 10.1006/Jmra.1993.1132}, url = {://WOS:A1993LJ62500010}, author = {Grandinetti, P. J. and Baltisberger, J. H. and Llor, A. and Lee, Y. K. and Werner, U. and Eastman, M. A. and Pines, A.} } @article {477, title = {Side-Band Patterns in Dynamic-Angle-Spinning Nmr}, journal = {Journal of Magnetic Resonance Series A}, volume = {102}, year = {1993}, note = {J Magn Reson Ser AKz480Times Cited:19Cited References Count:26}, month = {Apr}, pages = {195-204}, keywords = {samples}, isbn = {1064-1858}, doi = {Doi 10.1006/Jmra.1993.1091}, url = {://WOS:A1993KZ48000011}, author = {Grandinetti, P. J. and Lee, Y. K. and Baltisberger, J. H. and Sun, B. Q. and Pines, A.} } @article {474, title = {Spin-Polarized Xe-129 Nmr-Study of a Polymer Surface}, journal = {Journal of Physical Chemistry}, volume = {97}, year = {1993}, note = {J Phys Chem-UsKp603Times Cited:51Cited References Count:48}, month = {Feb 25}, pages = {1649-1655}, abstract = {

A method for NMR studies of low surface area materials using optically pumped xenon gas is described. The method has been used to investigate spin-polarized xenon adsorbed onto poly(acrylic acid). The temperature dependence of the xenon-surface interaction, as measured by the xenon chemical shifts extrapolated to zero pressure, is shown to be consistent with a simple model of chemical exchange between the gas and adsorbed phases. The magnitude of the surface contribution to the Xe-129 chemical shift indicates a relatively strong interaction between xenon and poly(acrylic acid), possibly due to the polar carboxylic acid functional groups at the polymer surface. From the pressure dependence of the Xe-129 shift, the diffusion coefficient of xenon on poly(acrylic acid) is estimated to be 3.3 x 10(-5) cm2/s.

}, keywords = {temperature}, isbn = {0022-3654}, doi = {Doi 10.1021/J100110a029}, url = {://WOS:A1993KP60300029}, author = {Raftery, D. and Reven, L. and Long, H. and Pines, A. and Tang, P. and Reimer, J. A.} } @article {483, title = {Squid-Nmr Study of Methyl Quantum Tunneling in a Series of Carboxylic-Acids}, journal = {Chemical Physics Letters}, volume = {201}, year = {1993}, note = {Chem Phys LettKf754Times Cited:12Cited References Count:23}, month = {Jan 8}, pages = {550-554}, abstract = {

Quantum tunneling frequencies of methyl groups at low temperature can be measured directly by low-field nuclear magnetic resonance (NMR) using our dc-SQUID (superconducting quantum interference device) spectrometer. From NMR spectra recorded in magnetic fields below 20 mT, tunneling frequencies between 140 and 250 kHz were measured for a homologous series of carboxylic acids at 4.2 K. For solids with equivalent crystal structures, we observe an exponential correlation between the tunneling frequency and the enthalpy of fusion; from this correlation we obtain information about the contribution of intermolecular interactions to the energy barrier for methyl rotation.

}, keywords = {nuclear}, isbn = {0009-2614}, doi = {Doi 10.1016/0009-2614(93)85115-5}, url = {://WOS:A1993KF75400026}, author = {Black, B. and Majer, G. and Pines, A.} } @article {471, title = {Squid-Nqr of N-14 in Amino-Acids and Small Peptides}, journal = {Chemical Physics Letters}, volume = {209}, year = {1993}, note = {Chem Phys LettLh246Times Cited:7Cited References Count:13}, month = {Jun 25}, pages = {17-21}, abstract = {

We present a technique for the study of nuclear quadrupole resonance of N-14 interacting with low electric field gradients as found, for example, in amino acids. A superconducting quantum interference device (SQUID) is used to detect directly small NMR signals via cross relaxation of the N-14 polarization to adjacent proton spins, eliminating the need for field cycling. When one nitrogen quadrupolar transition matches the proton Zeeman splitting, the remaining two quadrupolar transitions can be observed by sweeping a saturating rf field through resonance. In addition, signal enhancement by simultaneous excitation of two nitro n resonances helps to identify connected transitions.

}, keywords = {resonance}, isbn = {0009-2614}, doi = {Doi 10.1016/0009-2614(93)87194-8}, url = {://WOS:A1993LH24600003}, author = {Werner, U. and Black, B. and Ziegeweid, M. and Pines, A.} } @article {480, title = {Variable-Angle 3-Dimensional Exchange Nuclear-Magnetic-Resonance Spectroscopy for the Study of Molecular-Motion in Complex Solids}, journal = {Journal of the American Chemical Society}, volume = {115}, year = {1993}, note = {J Am Chem SocLf062Times Cited:14Cited References Count:23}, month = {Jun 2}, pages = {4825-4829}, abstract = {

Although molecular motions are responsible for many of the macroscopic properties observed in solids, especially in polymers, methods for studying these processes in all but the simplest systems are scarce. In the present study we introduce a three-dimensional nuclear magnetic resonance experiment for characterizing ultraslow molecular motions in complex solid systems. The technique extracts dynamic information by resolving the two-dimensional exchange distributions that can be observed in spectra of static samples, according to the isotropic chemical shifts of individual molecular sites. These three-dimensional correlations are achieved by processing signals arising from a fast-spinning solid sample using two independent macroscopic axes of rotation as extraction parameters, an approach which becomes practical due to the simple scaling behavior of anisotropic chemical shifts with respect to the axis of sample rotation. The principles involved in this new spectroscopic technique are discussed, and the method is illustrated with an application to the analysis of motions in isotactic polypropylene.

}, keywords = {jumps}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja00064a050}, url = {://WOS:A1993LF06200050}, author = {Frydman, L. and Lee, Y. K. and Emsley, L. and Chingas, G. C. and Pines, A.} } @article {494, title = {Adsorption Effects in Aluminophosphate Molecular-Sieves Studied by Al-27 Double-Rotation Nmr}, journal = {Catalysis Letters}, volume = {15}, year = {1992}, note = {Catal LettJj259Times Cited:18Cited References Count:17}, pages = {65-73}, abstract = {

Al-27 double rotation NMR (DOR) spectroscopy is used to investigate structural changes in the framework of several aluminophosphate molecular sieves upon adsorption of water. The shapes, widths, and positions of the spectral lines yield information on the aluminum environments, adsorption sites, and degree of structural disorder undergone upon water adsorption.

}, keywords = {alpo4-8}, isbn = {1011-372X}, doi = {Doi 10.1007/Bf00770899}, url = {://WOS:A1992JJ25900008}, author = {Jelinek, R. and Chmelka, B. F. and Wu, Y. and Davis, M. E. and Ulan, J. G. and Gronsky, R. and Pines, A.} } @article {496, title = {Correlation of Isotropic and Anisotropic Chemical-Shifts in Solids by 2-Dimensional Variable-Angle-Spinning Nmr}, journal = {Israel Journal of Chemistry}, volume = {32}, year = {1992}, note = {Israel J ChemKt517Times Cited:29Cited References Count:19}, pages = {161-164}, abstract = {

We describe a new solid-state nuclear magnetic resonance (NMR) technique for correlating anisotropic and isotropic chemical shifts in powdered samples. Two-dimensional (2D) NMR spectra are obtained by processing signals acquired in independent experiments for different angles between the sample spinning axis and the Zeeman magnetic field. This 2D NMR approach can therefore resolve individual static anisotropic lineshapes according to their isotropic chemical shift frequencies, without use of sudden mechanical motions or multiple-pulse irradiation schemes. Applications of the technique are illustrated with an analysis of the chemical shift anisotropy for the eight distinct C-13 sites in tyrosine.

}, keywords = {magic-angle}, isbn = {0021-2148}, url = {://WOS:A1992KT51700005}, author = {Frydman, L. and Chingas, G. C. and Lee, Y. K. and Grandinetti, P. J. and Eastman, M. A. and Barrall, G. A. and Pines, A.} } @article {499, title = {Double-Tuned Hopping-Coil Probe for Dynamic-Angle-Spinning Nmr}, journal = {Journal of Magnetic Resonance}, volume = {98}, year = {1992}, note = {J Magn ResonHz623Times Cited:29Cited References Count:13}, month = {Jun 15}, pages = {333-341}, keywords = {axis}, isbn = {0022-2364}, doi = {Doi 10.1016/0022-2364(92)90136-U}, url = {://WOS:A1992HZ62300008}, author = {Eastman, M. A. and Grandinetti, P. J. and Lee, Y. K. and Pines, A.} } @article {492, title = {Isotropic Chemical-Shifts and Quadrupolar Parameters for O-17 Using Dynamic-Angle Spinning Nmr}, journal = {Journal of Physical Chemistry}, volume = {96}, year = {1992}, note = {J Phys Chem-UsJk807Times Cited:66Cited References Count:48}, month = {Aug 20}, pages = {7001-7004}, abstract = {

Several oxygen-17-enriched silicates were studied using dynamic-angle spinning (DAS) NMR spectroscopy at two magnetic field strengths. The DAS method averages second-order quadrupolar interactions by reorienting a sample about a time-dependent axis, thereby yielding high-resolution spectra for half-odd integer spin quadrupolar nuclei such as oxygen-17. A narrow spectral line is observed for each distinct oxygen site in a powdered sample at the sum of the isotropic chemical shift and the field-dependent isotropic second-order quadrupolar shift. Using equations for the total shift observed at two field strengths, the chemical shift is uniquely determined together with a product of the quadrupolar coupling constant (C(Q) = e2qQ/h) and the quadrupolar asymmetry parameter (eta). For one silicate, we demonstrate aa computer program that uses the isotropic shifts and quadrupolar products as constraints and provides simulations of overlapped magic-angle spinning line shapes. In this way the quadrupolar parameters, C(Q) and eta, are determined separately for each crystallographic site. The silicates studied include the discrete orthosilicates larnite (Ca2SiO4) and forsterite (Mg2SiO4), as well as diopside (CaMgSi2O6), wollastonite (CaSiO3), and clinoenstatite (MgSiO3), which are minerals composed of chains of silicon-oxygen tetrahedra.

}, keywords = {zeolites}, isbn = {0022-3654}, doi = {Doi 10.1021/J100196a028}, url = {://WOS:A1992JK80700028}, author = {Mueller, K. T. and Baltisberger, J. H. and Wooten, E. W. and Pines, A.} } @article {491, title = {Multiple-Quantum Nmr-Study of the Distribution of Benzene in Nay Zeolite}, journal = {Journal of Physical Chemistry}, volume = {96}, year = {1992}, note = {J Phys Chem-UsJu555Times Cited:26Cited References Count:24}, month = {Oct 15}, pages = {8517-8522}, abstract = {

We have used multiple-quantum NMR to measure the apparent spin network size as a function of excitation time of NaY zeolite samples containing varying amounts of benzene. Behavior observed at low concentrations of benzene was consistent with the presence of isolated clusters of benzene molecules in the supercages, with a statistical distribution of benzene molecules between supercages. Behavior observed at high concentrations of benzene was consistent with the presence of weakly coupled clusters of benzene molecules, with a uniform distribution of benzene molecules between supercages.

}, keywords = {solids}, isbn = {0022-3654}, doi = {Doi 10.1021/J100200a057}, url = {://WOS:A1992JU55500057}, author = {Pearson, J. G. and Chmelka, B. F. and Shykind, D. N. and Pines, A.} } @inbook {486, title = {New Angles in Motional Averaging}, booktitle = {Pulsed magnetic resonance: NMR, ESR and optics: A recognition of E.L. Hahn}, year = {1992}, pages = {80 - 94}, publisher = {Claredon Press}, organization = {Claredon Press}, chapter = {3}, address = {Oxford}, author = {Samoson, A. and Sun, B.Q. and Pines, A.}, editor = {Bagguley, D.M.S.} } @article {484, title = {New Angles in Nuclear-Magnetic-Resonance Sample Spinning}, journal = {Accounts of Chemical Research}, volume = {25}, year = {1992}, note = {Accounts Chem ResHu248Times Cited:41Cited References Count:29}, month = {May}, pages = {209-215}, keywords = {axis}, isbn = {0001-4842}, doi = {Doi 10.1021/Ar00017a001}, url = {://WOS:A1992HU24800001}, author = {Wooten, E. W. and Mueller, K. T. and Pines, A.} } @article {489, title = {Nmr of Optically Pumped Xenon Thin-Films}, journal = {Chemical Physics Letters}, volume = {191}, year = {1992}, note = {Chem Phys LettHp501Times Cited:25Cited References Count:25}, month = {Apr 10}, pages = {385-390}, abstract = {

NMR of Xe-129 has been observed in thin films of xenon frozen onto the surfaces of glass sample cells with various geometries. The Xe-129 polarization was enhanced by optical pumping, and the xenon was then transferred to a high-field pulsed NMR spectrometer allowing the observation of strong signals from xenon films of approximately 1-mu-m thickness. The line shape depends on the film geometry because of the bulk diamagnetic susceptibility chi(D) of solid xenon. The spectral line shape and resonance frequency also depend on temperature.

}, isbn = {0009-2614}, doi = {Doi 10.1016/0009-2614(92)85396-R}, url = {://WOS:A1992HP50100002}, author = {Raftery, D. and Long, H. and Reven, L. and Tang, P. and Pines, A.} } @article {487, title = {Nmr-Studies of the Surface-Structure and Dynamics of Semiconductor Nanocrystals}, journal = {Chemical Physics Letters}, volume = {198}, year = {1992}, note = {Chem Phys LettJt385Times Cited:77Cited References Count:27}, month = {Oct 16}, pages = {431-436}, abstract = {

H-1 NMR studies of thiophenol capping groups on cadmium sulfide nanocrystals demonstrate that the coverage of the capping molecule depends on the size of the nanocrystal. Data are presented which show that as the size of the nanocrystal increases, the coverage of thiophenol decreases. In addition, information about the overall tumbling of the nanocrystal and the motion of the capping groups relative to the surface can be obtained from linewidth studies, indicating that the rotation of the capping groups is hindered in the smaller nanocrystals (r almost-equal-to 12 angstrom) and becomes less so in larger nanocrystals (r almost-equal-to 20 angstrom). The coverage data are related to the electronic properties of this important class of compounds.

}, keywords = {relaxation}, isbn = {0009-2614}, doi = {Doi 10.1016/0009-2614(92)80023-5}, url = {://WOS:A1992JT38500001}, author = {Sachleben, J. R. and Wooten, E. W. and Emsley, L. and Pines, A. and Colvin, V. L. and Alivisatos, A. P.} } @article {495, title = {Pulsed Fourier-Transform Nqr of N-14 with a Dc Squid}, journal = {Physical Review Letters}, volume = {69}, year = {1992}, note = {Phys Rev LettJe754Times Cited:23Cited References Count:27}, month = {Jul 27}, pages = {684-687}, abstract = {

The zero-field free induction decay of solid ammonium perchlorate at 1.5 K has been directly detected with a dc superconducting quantum interference device. The Fourier-transform spectrum consists of three sharp lines at 17.4, 38.8, and 56.2 kHz arising from pure N-14 nucLear quadrupole resonance transitions. The absence of splittings and resonance transitions from dipolar-coupled proton spins is attributed to reorientation of the ammonium groups by quantum tunneling in combination with motional averaging in the three proton levels characterized by the irreducible representation T. The measured N-14 spin-spin relaxation time is 22+/-2 ms and the spin-lattice relaxation time is 63+/-6 ms.

}, keywords = {nh4clo4}, isbn = {0031-9007}, doi = {Doi 10.1103/Physrevlett.69.684}, url = {://WOS:A1992JE75400034}, author = {Hurlimann, M. D. and Pennington, C. H. and Fan, N. Q. and Clarke, J. and Pines, A. and Hahn, E. L.} } @article {498, title = {Quantification of the Disorder in Network-Modified Silicate-Glasses}, journal = {Nature}, volume = {358}, year = {1992}, note = {NatureJb341Times Cited:169Cited References Count:32}, month = {Jul 2}, pages = {31-35}, abstract = {

Local order in silicate glasses has been observed by many experimental techniques to be similar to that in crystalline materials. Details of the intermediate-range order are more elusive, but essential for understanding the lack of long-range symmetry in glasses and the effect of composition on glass structure. Two-dimensional O-17 dynamic-angle-spinning nuclear magnetic resonance experiments reveal intermediate-range order in the distribution of inter-tetrahedral (Si-O-Si) bond angles and a high degree of order in the disposition of oxygen atoms around the network-modifying cations.

}, keywords = {time}, isbn = {0028-0836}, doi = {Doi 10.1038/358031a0}, url = {://WOS:A1992JB34100043}, author = {Farnan, I. and Grandinetti, P. J. and Baltisberger, J. H. and Stebbins, J. F. and Werner, U. and Eastman, M. A. and Pines, A.} } @article {500, title = {Rb-87 Dynamic-Angle Spinning Nmr-Spectroscopy of Inorganic Rubidium Salts}, journal = {Journal of the American Chemical Society}, volume = {114}, year = {1992}, note = {J Am Chem SocJm979Times Cited:39Cited References Count:28}, month = {Sep 9}, pages = {7489-7493}, abstract = {

Five inorganic rubidium salts, RbCl, RbClO4, Rb2SO4, Rb2CrO4, and RbNO3, were examined using Rb-87 NMR spectroscopy. Significant line narrowing occurs under dynamic-angle spinning (DAS) compared to magic-angle spinning (MAS) or variable-angle spinning (VAS). From DAS spectra acquired at various magnetic field strengths, isotropic chemical shifts and isotropic second-order quadrupolar shifts were obtained. By simulations of single-site line shapes obtained from MAS-detected DAS experiments, complete chemical shift and quadrupolar parameters were determined for each of the three crystallographically distinct rubidium sites in RbNO3.

}, keywords = {cesium}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja00045a023}, url = {://WOS:A1992JM97900023}, author = {Baltisberger, J. H. and Gann, S. L. and Wooten, E. W. and Chang, T. H. and Mueller, K. T. and Pines, A.} } @article {485, title = {Sidebands in dynamic angle spinning (DAS) and double rotation (DOR) NMR}, journal = {Solid State Nuclear Magnetic Resonance}, volume = {1}, year = {1992}, note = {Solid State Nucl MagV26htTimes Cited:63Cited References Count:29}, month = {Dec}, pages = {267-295}, abstract = {

A theory of dynamic angle spinning (DAS) and double rotation (DOR) NMR is described using average Hamiltonian and irreducible tensor methods. Sideband intensities in DAS and DOR spectra are analyzed by both the moment and Bessel function methods, and general formulae are derived. Results show that the DAS moments depend on the relative rotor phase between the first and the second evolution periods, whereas the second and third DOR moments are independent of the relative phase between the inner and outer rotors. Sideband intensities in DAS spectra also depend on the relative rotor phases between evolution at the first and second angles, as well as on the ratio of time spent at each angle. Sideband intensities and phases in DOR spectra are related to the relative rotor phases between the inner and outer rotors, and the sideband pattern is determined by the ratio of the inner and outer rotor spinning speeds. An inversion symmetry of the odd numbered DOR sidebands at the relative rotor phase gamma(r) = 0 degrees. 180 degrees permits the elimination of these sidebands. Finally, numerical simulations are implemented and shown to agree with experimental results. Quadrupolar parameters can therefore be recovered either by calculating the second and third moments or by simulating the sideband intensities and phases.

}, keywords = {central transition}, isbn = {0926-2040}, doi = {Doi 10.1016/0926-2040(92)90047-D}, url = {://WOS:000208537400006}, author = {Sun, B. Q. and Baltisberger, J. H. and Wu, Y. and Samoson, A. and Pines, A.} } @article {488, title = {Solid-state Al-27 NMR studies of aluminophosphate molecular sieves}, journal = {Solid State Nuclear Magnetic Resonance}, volume = {1}, year = {1992}, note = {Solid State Nucl MagV26hsTimes Cited:12Cited References Count:33}, month = {Nov}, pages = {217-225}, abstract = {Solid-state Al-27 NMR spectra of several aluminophosphate molecular sieves have been recorded with conventional magic-angle spinning (MAS), double-rotation (DOR) and quadrupole nutation with fast MAS. Enhanced resolution was obtained in the quadrupole nutation experiment at certain radiofrequency pulse strengths. This extra resolution can be comparable to that attainable using DOR, and does not introduce spinning sidebands.}, keywords = {double-rotation}, isbn = {0926-2040}, url = {://WOS:000208537300007}, author = {Rocha, J. and Klinowski, J. and Barrie, P. J. and Jelinek, R. and Pines, A.} } @article {490, title = {Solid-State Nmr - Some Personal Recollections}, journal = {Israel Journal of Chemistry}, volume = {32}, year = {1992}, note = {Israel J ChemKt517Times Cited:1Cited References Count:0}, pages = {137-144}, isbn = {0021-2148}, url = {://WOS:A1992KT51700003}, author = {Pines, A.} } @article {493, title = {A study of nanostructure assemblies and guest-host interactions in sodium zeolite-Y using Na-23 double rotation NMR}, journal = {Nanotechnology}, year = {1992}, pages = {182-186}, author = {Jelinek, R. and Pines, A. and Ozkar, S. and Ozin, G.A.} } @article {497, title = {Variable-Angle Correlation Spectroscopy in Solid-State Nuclear-Magnetic-Resonance}, journal = {Journal of Chemical Physics}, volume = {97}, year = {1992}, note = {J Chem PhysJr338Times Cited:90Cited References Count:28}, month = {Oct 1}, pages = {4800-4808}, abstract = {

We describe here a new solid-state nuclear-magnetic-resonance (NMR) experiment for correlating anisotropic and isotropic chemical shifts of inequivalent nuclei in powdered samples. Spectra are obtained by processing signals arising from a spinning sample, acquired in independent experiments as a function of the angle between the axis of macroscopic rotation and the external magnetic field. This is in contrast to previously proposed techniques, which were based on sudden mechanical flippings or multiple-pulse sequences. We show that the time evolution of variable-angle-spinning signals is determined by a distribution relating the isotropic frequencies of the spins with their corresponding chemical shift anisotropies. Fourier transformation of these data therefore affords a two-dimensional NMR spectrum, in which line shapes of isotropic and anisotropic interactions are correlated. Theoretical and experimental considerations involved in the extraction of this spectral information are discussed, and the technique is illustrated by an analysis of C-13 NMR anisotropy in glycine, cysteine, and p-anisic acid.

}, keywords = {axis}, isbn = {0021-9606}, doi = {Doi 10.1063/1.463860}, url = {://WOS:A1992JR33800022}, author = {Frydman, L. and Chingas, G. C. and Lee, Y. K. and Grandinetti, P. J. and Eastman, M. A. and Barrall, G. A. and Pines, A.} } @article {503, title = {C-13 Nmr in Solids - a Citation-Classic Commentary on Proton-Enhanced Nmr of Dilute Spins in Solids by Pines,A., Gibby,M.G., and Waugh,J.S.}, journal = {Current Contents/Physical Chemical \& Earth Sciences}, year = {1991}, note = {Cc/Phys Chem EarthFy134Times Cited:0Cited References Count:2}, month = {Aug 12}, pages = {10-10}, isbn = {0163-2574}, url = {://WOS:A1991FY13400001}, author = {Pines, A.} } @conference {509, title = {Framework ordering in aluminophosphate molecular sieves studied by (27)Al double rotation NMR}, volume = {69}, year = {1991}, month = {1991}, pages = {435-442}, publisher = {Elsevier}, organization = {Elsevier}, author = {Chmelka, B.F. and Wu, Y. and Jelinek, R. and Davis, M.E. and Pines, A.}, editor = {P.A. Jacobs, N.I. Jaeger, L. Kubelkova, and B. Wichterlov} } @article {501, title = {High-Field Nmr of Adsorbed Xenon Polarized by Laser Pumping}, journal = {Physical Review Letters}, volume = {66}, year = {1991}, note = {Phys Rev LettEv897Times Cited:202Cited References Count:35}, month = {Feb 4}, pages = {584-587}, abstract = {

Optical pumping has been used to enhance the pulsed NMR signal of Xe-129, allowing the detection of low-pressure xenon gas and of xenon adsorbed on powdered solids. We observe an increase in sensitivity of more than 2 orders of magnitude over conventional NMR, the current limitation being the laser power. Adsorbed xenon is observed at 298 K on graphitized carbon (10 m2/g) and on powdered benzanthracene (approximately 0.5 m2/g) below 170 K. The increased sensitivity of this technique allows the study of a large class of amorphous materials with surface areas below 10 m2/g including semiconductors, polymers, metal oxides, and catalysts.

}, keywords = {solids}, isbn = {0031-9007}, doi = {Doi 10.1103/Physrevlett.66.584}, url = {://WOS:A1991EV89700017}, author = {Raftery, D. and Long, H. and Meersmann, T. and Grandinetti, P. J. and Reven, L. and Pines, A.} } @article {504, title = {High-Resolution O-17 Nmr of Solid Silicates}, journal = {Journal of the American Chemical Society}, volume = {113}, year = {1991}, note = {J Am Chem SocEr082Times Cited:90Cited References Count:39}, month = {Jan 2}, pages = {32-38}, abstract = {

Several O-17-enriched silicates were studied by use of dynamic angle spinning (DAS) and double rotation (DOR) nuclear magnetic resonance spectroscopy. These methods average away second-order quadrupolar interactions by reorienting a sample about a time-dependent axis, thereby yielding high-resolution spectra of oxygen-17 nuclei. A narrow spectral line is observed for each distinct oxygen site at the sum of the isotropic chemical shift and the field-dependent isotropic second-order quadrupolar shift. Resolution is increased by up to 2 orders of magnitude compared to conventional magic angle spinning (MAS) spectra. Crystallographically inequivalent oxygens are now observable as distinct resonances in spectra of polycrystalline silicates such as diopside (CaMgSi2(17)O6), wollastonite (CaSi17O3), clinoenstatite (MgSi17O3), larnite (Ca2Si17O4),and forsterite (Mg2Si17O4).

}, keywords = {spectra}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja00001a006}, url = {://WOS:A1991ER08200006}, author = {Mueller, K. T. and Wu, Y. and Chmelka, B. F. and Stebbins, J. and Pines, A.} } @article {510, title = {Measurement of Xenon Distribution Statistics in Na-a Zeolite Cavities}, journal = {Physical Review Letters}, volume = {66}, year = {1991}, note = {Phys Rev LettEv897Times Cited:78Cited References Count:21}, month = {Feb 4}, pages = {580-583}, abstract = {

Xe-129 NMR spectroscopy has been used to probe directly the distribution of xenon atoms confined in atomic-size Na-A zeolite cavities. For mean xenon occupancies less than about three Xe atoms per a-cage, the guest populations are well described by binomial statistics. At higher guest loadings the finite volumes of the xenon atoms become significant, as reflected by a fit of the experimental populations with a hypergeometric distribution, with a maximum of seven Xe atoms per cage. At the highest xenon loadings the experimental distribution is narrower than hypergeometric, as predicted by Monte Carlo simulations.

}, keywords = {fluids}, isbn = {0031-9007}, doi = {Doi 10.1103/Physrevlett.66.580}, url = {://WOS:A1991EV89700016}, author = {Chmelka, B. F. and Raftery, D. and Mccormick, A. V. and Demenorval, L. C. and Levine, R. D. and Pines, A.} } @article {506, title = {Nmr Probe for Dynamic-Angle Spinning}, journal = {Review of Scientific Instruments}, volume = {62}, year = {1991}, note = {Rev Sci InstrumFp312Times Cited:31Cited References Count:35}, month = {Jun}, pages = {1445-1452}, abstract = {

We describe the design of a probe for dynamic-angle spinning (DAS) NMR experiments, comprised of a spinning cylindrical sample holder whose axis may be reoriented rapidly between discrete directions within the bore of a superconducting magnet. This allows the refocusing of nuclear spin magnetization that evolves under anisotropic interactions such as chemical shift anisotropy and quadrupolar coupling, providing high resolution NMR spectra for quadrupolar nuclei in solid materials. The probe includes an axial air delivery system to bearing and drive jets which support and spin a rotor containing the sample. Axis reorientation is accomplished with a pulley attached to the probehead and coupled to a stepping motor outside of the magnet. The choice of motor and gear ratio is based on an analysis of the moments of inertia of the motor and load, the desired angular resolution, and simplicity of design. Control of angular accuracy and precision are discussed, as well as the efficiency of radiofrequency irradiation and detection. High resolution DAS spectra of oxygen-17 and aluminum-27 nuclei in polycrystalline minerals illustrate the experimental capabilities.

}, keywords = {minerals}, isbn = {0034-6748}, doi = {Doi 10.1063/1.1142465}, url = {://WOS:A1991FP31200011}, author = {Mueller, K. T. and Chingas, G. C. and Pines, A.} } @article {511, title = {Nmr-Study of the Distribution of Aromatic-Molecules in Nay Zeolite}, journal = {Journal of Physical Chemistry}, volume = {95}, year = {1991}, note = {J Phys Chem-UsEr473Times Cited:70Cited References Count:64}, month = {Jan 10}, pages = {303-310}, abstract = {

Local and macroscopic distributions of adsorbed benzene, 1,3,5-trimethylbenzene, and hexamethylbenzene (HMB) molecules among the intracrystalline of NaY zeolite samples have been investigated by Xe-129 and multiple-quantum NMR. Xenon-129 NMR, a sensitive probe of macroscopic distributions of molecules in zeolites at room temperature, demonstrates the importance of sample heat treatment in distributing an adsorbate homogeneously throughout a collection of zeolite particles. NaY samples containing organic guests adsorbed a temperatures near the bulk species\&$\#$39; melting point produce multiple or broad xenon lines characteristic of macroscopic (i.e., interparticle) adsorbate concentration gradients. After thorough heat treatment of the samples at elevated temperatures, the xenon spectrum collapses to a single sharp line, consistent with a macroscopically uniform distribution. For HMB adsorbed in NaY, \"counting\" hydrogen clusters by multiple-quantum NMR reveals intraparticle HMB distributions consistent with one molecular per cavity at low loadings (average bulk loading less-than-or-equal-to 1 molecule per cavity) and two molecules per cavity at higher loadings.

}, keywords = {catalysts}, isbn = {0022-3654}, doi = {Doi 10.1021/J100154a056}, url = {://WOS:A1991ER47300056}, author = {Chmelka, B. F. and Pearson, J. G. and Liu, S. B. and Ryoo, R. and Demenorval, L. C. and Pines, A.} } @article {505, title = {Pure-Absorption-Phase Dynamic-Angle Spinning}, journal = {Journal of Magnetic Resonance}, volume = {92}, year = {1991}, note = {J Magn ResonFj100Times Cited:30Cited References Count:15}, month = {May}, pages = {620-627}, keywords = {nuclei}, isbn = {0022-2364}, doi = {Doi 10.1016/0022-2364(91)90359-2}, url = {://WOS:A1991FJ10000018}, author = {Mueller, K. T. and Wooten, E. W. and Pines, A.} } @article {507, title = {Scaling and Time-Reversal of Spin Couplings in Zero-Field Nmr}, journal = {Physical Review Letters}, volume = {67}, year = {1991}, note = {Phys Rev LettGj319Times Cited:13Cited References Count:25}, month = {Oct 7}, pages = {1989-1992}, abstract = {

We report the observation of spin echoes resulting from the time reversal of isotropic many-body spin couplings in zero-field NMR. The coherent-averaging pulse sequences responsible for the scaling and the time reversal of isotropic interactions of first and second rank are based on cubic and icosahedral symmetry.

}, keywords = {nqr}, isbn = {0031-9007}, doi = {Doi 10.1103/Physrevlett.67.1989}, url = {://WOS:A1991GJ31900014}, author = {Llor, A. and Olejniczak, Z. and Sachleben, J. and Pines, A.} } @article {508, title = {Study of the Aluminophosphates Alpo4-21 and Alpo4-25 by Al-27 Double-Rotation Nmr}, journal = {Journal of the American Chemical Society}, volume = {113}, year = {1991}, note = {J Am Chem SocFn005Times Cited:53Cited References Count:16}, month = {May 22}, pages = {4097-4101}, abstract = {

Aluminum-27 double-rotation NMR in a magnetic field of 11.7 T distinguishes the extremely distorted five-coordinated aluminum sites in the molecular sieve precursor ALPO4(-21). Upon calcination, ALPO4(-21) transforms to ALPO4(-25), which has two tetrahedral aluminum sites with similar isotropic chemical shifts that cannot be resolved in an 11.7 T field. The two tetrahedral environments, however, have a different quadrupole coupling constants and are distinguished by double rotation at 4.2 T field. The quadrupole coupling constants obtained for these sites indicates that the tetrahedral aluminum environments are less distorted in the hydrated material.

}, keywords = {nuclei}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja00011a007}, url = {://WOS:A1991FN00500007}, author = {Jelinek, R. and Chmelka, B. F. and Wu, Y. and Grandinetti, P. J. and Pines, A. and Barrie, P. J. and Klinowski, J.} } @article {522, title = {2-Dimensional Nmr-Studies of Flexible Molecules in Liquid-Crystals - Orientational Order and Conformational Probabilities of N-Hexane}, journal = {Molecular Physics}, volume = {69}, year = {1990}, note = {Mol PhysCy544Times Cited:38Cited References Count:55}, month = {Mar}, pages = {671-695}, isbn = {0026-8976}, doi = {Doi 10.1080/00268979000100501}, url = {://WOS:A1990CY54400007}, author = {Gochin, M. and Pines, A. and Rosen, M. E. and Rucker, S. P. and Schmidt, C.} } @proceedings {519, title = {Abelian and non-abelian holonomy in NMR interferometry}, journal = {Proc. of the Conference on Fundamental Aspects of Quantum Theory}, year = {1990}, publisher = {World Scientific Press}, author = {Pines, A. and Meuller, K.T.}, editor = {Anandan, J.} } @article {524, title = {Aluminum and Boron Nuclear-Quadrupole Resonance with a Direct-Current Superconducting Quantum Interference Device}, journal = {Journal of Chemical Physics}, volume = {93}, year = {1990}, note = {J Chem PhysEl294Times Cited:12Cited References Count:49}, month = {Dec 1}, pages = {7639-7646}, isbn = {0021-9606}, doi = {Doi 10.1063/1.459395}, url = {://WOS:A1990EL29400010}, author = {Connor, C. and Chang, J. and Pines, A.} } @article {513, title = {Berrys Phase}, journal = {Annual Review of Physical Chemistry}, volume = {41}, year = {1990}, note = {Annu Rev Phys ChemEf685Times Cited:96Cited References Count:286}, pages = {601-646}, isbn = {0066-426X}, doi = {Doi 10.1146/Annurev.Pc.41.100190.003125}, url = {://WOS:A1990EF68500020}, author = {Zwanziger, J. W. and Koenig, M. and Pines, A.} } @article {521, title = {Dynamic-Angle Spinning of Quadrupolar Nuclei}, journal = {Journal of Magnetic Resonance}, volume = {86}, year = {1990}, note = {J Magn ResonCu525Times Cited:288Cited References Count:32}, month = {Feb 15}, pages = {470-487}, isbn = {0022-2364}, doi = {Doi 10.1016/0022-2364(90)90025-5}, url = {://WOS:A1990CU52500003}, author = {Mueller, K. T. and Sun, B. Q. and Chingas, G. C. and Zwanziger, J. W. and Terao, T. and Pines, A.} } @article {517, title = {A Fast, Stable Quadrature Phase Generator for Multiple-Pulse Nmr}, journal = {Review of Scientific Instruments}, volume = {61}, year = {1990}, note = {Rev Sci InstrumDc425Times Cited:8Cited References Count:14}, month = {May}, pages = {1474-1479}, isbn = {0034-6748}, doi = {Doi 10.1063/1.1141155}, url = {://WOS:A1990DC42500016}, author = {Shykind, D. N. and Chingas, G. C. and Pines, A. and Shaka, A. J.} } @article {515, title = {High-Resolution Al-27 Nmr-Spectroscopy of the Aluminophosphate Molecular-Sieve Vpi-5}, journal = {Nature}, volume = {346}, year = {1990}, note = {NatureDt679Times Cited:97Cited References Count:12}, month = {Aug 9}, pages = {550-552}, isbn = {0028-0836}, doi = {Doi 10.1038/346550a0}, url = {://WOS:A1990DT67900067}, author = {Wu, Y. and Chmelka, B. F. and Pines, A. and Davis, M. E. and Grobet, P. J. and Jacobs, P. A.} } @article {523, title = {Investigations of Adsorbed Organic-Molecules in Na-Y Zeolite by Xe-129 Nmr}, journal = {Journal of Physical Chemistry}, volume = {94}, year = {1990}, note = {J Phys Chem-UsCh532Times Cited:61Cited References Count:26}, month = {Jan 11}, pages = {27-31}, isbn = {0022-3654}, doi = {Doi 10.1021/J100364a006}, url = {://WOS:A1990CH53200006}, author = {Demenorval, L. C. and Raftery, D. and Liu, S. B. and Takegoshi, K. and Ryoo, R. and Pines, A.} } @article {525, title = {Magnetic-Resonance Spectrometer with a Dc Squid Detector}, journal = {Review of Scientific Instruments}, volume = {61}, year = {1990}, note = {Rev Sci InstrumCu216Times Cited:30Cited References Count:19}, month = {Mar}, pages = {1059-1063}, isbn = {0034-6748}, doi = {Doi 10.1063/1.1141476}, url = {://WOS:A1990CU21600021}, author = {Connor, C. and Chang, J. and Pines, A.} } @article {514, title = {Nmr Experiments with a New Double Rotor}, journal = {Journal of Magnetic Resonance}, volume = {89}, year = {1990}, note = {J Magn ResonDu813Times Cited:113Cited References Count:13}, month = {Sep}, pages = {297-309}, isbn = {0022-2364}, doi = {Doi 10.1016/0022-2364(90)90236-3}, url = {://WOS:A1990DU81300008}, author = {Wu, Y. and Sun, B. Q. and Pines, A. and Samoson, A. and Lippmaa, E.} } @article {520, title = {NMR in physics, chemistry and biology: Illustrations of Bloch{\textquoteright}s legacy in proceedings of the Bloch symposium}, journal = {International Journal of Modern Physics B}, volume = {4}, year = {1990}, pages = {1241-1267}, author = {Pines, A.} } @article {512, title = {Non-Abelian Effects in a Quadrupole System Rotating around 2 Axes}, journal = {Physical Review A}, volume = {42}, year = {1990}, note = {Phys Rev ADy007Times Cited:30Cited References Count:22}, month = {Sep 1}, pages = {3107-3110}, isbn = {1050-2947}, doi = {Doi 10.1103/Physreva.42.3107}, url = {://WOS:A1990DY00700066}, author = {Zwanziger, J. W. and Koenig, M. and Pines, A.} } @article {518, title = {Nuclear Magnetic Resonance}, journal = {Spectroscopy}, volume = {5}, year = {1990}, pages = {34-35}, author = {Pines, A. and Wu, Y.} } @article {516, title = {A suggestion for detecting rotational tunnelling of CD3: Groups by mulitple quantum spectroscopy}, journal = {Bulletin of Magnetic Resonance}, volume = {12}, year = {1990}, pages = {9-14}, author = {Werner, U. and Muller-Warmuth, W. and Pines, A.} } @inbook {555, title = {Calcination-dependence ofplatinum cluster formation in NaY zeolite: A xenon-129 NMR study}, booktitle = {Structure and Reactivity of Surfaces}, year = {1989}, pages = {269-278}, publisher = {Elsevier Science Publishers}, organization = {Elsevier Science Publishers}, address = {Amsterdam}, author = {Chmelka, B.F. and de Menorval, L.C. and Csencsits, R. and Ryoo, R. and Liu, S.B. and Radke, C.J. and Petersen, E.E. and Pines, A.}, editor = {C. Morterra, A. Zecchina, and G. Costa} } @article {556, title = {Direct Detection of Al-27 Resonance with a Squid Spectrometer}, journal = {Journal of Magnetic Resonance}, volume = {82}, year = {1989}, note = {J Magn ResonU1146Times Cited:16Cited References Count:13}, month = {Apr}, pages = {387-391}, isbn = {0022-2364}, doi = {Doi 10.1016/0022-2364(89)90044-9}, url = {://WOS:A1989U114600019}, author = {Chang, J. and Connor, C. and Hahn, E. L. and Huber, H. and Pines, A.} } @booklet {549, title = {Double Rotor for Solid-State Nmr}, journal = {Review of Scientific Instruments}, volume = {60}, year = {1989}, note = {Rev Sci InstrumAu005Times Cited:54Cited References Count:12}, month = {Oct}, pages = {3239-3241}, isbn = {0034-6748}, doi = {Doi 10.1063/1.1140558}, url = {://WOS:A1989AU00500021}, author = {Samoson, A. and Pines, A.} } @article {552, title = {Frequency Selective Nmr Pulse Sequences Generated by Iterative Schemes with Multiple Fixed-Points}, journal = {Molecular Physics}, volume = {67}, year = {1989}, note = {Mol PhysAf151Times Cited:3Cited References Count:24}, month = {Jun 20}, pages = {505-516}, isbn = {0026-8976}, doi = {Doi 10.1080/00268978900101251}, url = {://WOS:A1989AF15100003}, author = {Cho, H. and Mueller, K. T. and Shaka, A. J. and Pines, A.} } @article {557, title = {Non-Abelian Geometric Phase from Incomplete Quantum Measurements}, journal = {Physics Letters A}, volume = {141}, year = {1989}, note = {Phys Lett ACb816Times Cited:19Cited References Count:16}, month = {Nov 13}, pages = {335-339}, isbn = {0375-9601}, doi = {Doi 10.1016/0375-9601(89)90060-1}, url = {://WOS:A1989CB81600005}, author = {Anandan, J. and Pines, A.} } @article {551, title = {Nuclear Magnetic-Resonance with Dc Squid Preamplifiers}, journal = {Ieee Transactions on Magnetics}, volume = {25}, year = {1989}, note = {Ieee T MagnT6706Times Cited:21Cited References Count:23}, month = {Mar}, pages = {1193-1199}, isbn = {0018-9464}, doi = {Doi 10.1109/20.92510}, url = {://WOS:A1989T670600113}, author = {Fan, N. Q. and Heaney, M. B. and Clarke, J. and Newitt, D. and Wald, L. L. and Hahn, E. L. and Bielecki, A. and Pines, A.} } @article {554, title = {O-17 Nmr in Solids by Dynamic-Angle Spinning and Double Rotation}, journal = {Nature}, volume = {339}, year = {1989}, note = {NatureU4451Times Cited:177Cited References Count:15}, month = {May 4}, pages = {42-43}, isbn = {0028-0836}, doi = {Doi 10.1038/339042a0}, url = {://WOS:A1989U445100054}, author = {Chmelka, B. F. and Mueller, K. T. and Pines, A. and Stebbins, J. and Wu, Y. and Zwanziger, J. W.} } @article {553, title = {Some Developments in Nuclear Magnetic-Resonance of Solids}, journal = {Science}, volume = {246}, year = {1989}, note = {ScienceAt607Times Cited:33Cited References Count:91}, month = {Oct 6}, pages = {71-77}, isbn = {0036-8075}, doi = {Doi 10.1126/Science.246.4926.71}, url = {://WOS:A1989AT60700032}, author = {Chmelka, B. F. and Pines, A.} } @article {550, title = {Suppression of the Zero Frequency Peak in Zero-Field Nmr}, journal = {Chemical Physics Letters}, volume = {158}, year = {1989}, note = {Chem Phys LettAb503Times Cited:1Cited References Count:22}, month = {Jun 9}, pages = {325-328}, isbn = {0009-2614}, doi = {Doi 10.1016/0009-2614(89)87345-2}, url = {://WOS:A1989AB50300029}, author = {Jarvie, T. P. and Takegoshi, K. and Suter, D. and Pines, A. and Zax, D. B.} } @article {559, title = {Broad-Band Heteronuclear Spin Decoupling in Solids}, journal = {Chemical Physics Letters}, volume = {144}, year = {1988}, note = {Chem Phys LettM4326Times Cited:19Cited References Count:11}, month = {Mar 4}, pages = {324-327}, isbn = {0009-2614}, doi = {Doi 10.1016/0009-2614(88)87122-7}, url = {://WOS:A1988M432600002}, author = {Suter, D. and Pines, A. and Lee, J. H. and Drobny, G.} } @article {568, title = {Diffusive Motion in Alkali Silicate Melts - an Nmr-Study at High-Temperature}, journal = {Geochimica Et Cosmochimica Acta}, volume = {52}, year = {1988}, note = {Geochim Cosmochim AcM3100Times Cited:79Cited References Count:67}, month = {Feb}, pages = {527-538}, isbn = {0016-7037}, doi = {Doi 10.1016/0016-7037(88)90108-1}, url = {://WOS:A1988M310000028}, author = {Liu, S. B. and Stebbins, J. F. and Schneider, E. and Pines, A.} } @article {565, title = {High-Resolution Solid-State Nmr Averaging of 2nd-Order Effects by Means of a Double-Rotor}, journal = {Molecular Physics}, volume = {65}, year = {1988}, note = {Mol PhysR5253Times Cited:405Cited References Count:34}, month = {Nov}, pages = {1013-1018}, isbn = {0026-8976}, doi = {Doi 10.1080/00268978800101571}, url = {://WOS:A1988R525300018}, author = {Samoson, A. and Lippmaa, E. and Pines, A.} } @article {563, title = {Iterative Carr-Purcell Trains}, journal = {Journal of Magnetic Resonance}, volume = {77}, year = {1988}, note = {J Magn ResonN4561Times Cited:39Cited References Count:13}, month = {May}, pages = {606-611}, isbn = {0022-2364}, doi = {Doi 10.1016/0022-2364(88)90022-4}, url = {://WOS:A1988N456100022}, author = {Shaka, A. J. and Rucker, S. P. and Pines, A.} } @article {564, title = {Iterative Schemes for Bilinear Operators - Application to Spin Decoupling}, journal = {Journal of Magnetic Resonance}, volume = {77}, year = {1988}, note = {J Magn ResonN1647Times Cited:752Cited References Count:31}, month = {Apr}, pages = {274-293}, isbn = {0022-2364}, doi = {Doi 10.1016/0022-2364(88)90178-3}, url = {://WOS:A1988N164700006}, author = {Shaka, A. J. and Lee, C. J. and Pines, A.} } @book {566, title = {Lectures on pulsed NMR in proceedings of the 100th school of physics Enrico Fermi}, year = {1988}, chapter = {43-120}, address = {North Holland, Amsterdam}, author = {Pines, A.}, editor = {Maraviglia, B.} } @article {562, title = {Multiple-Pulse Sequences for Precise Transmitter Phase Alignment}, journal = {Journal of Magnetic Resonance}, volume = {80}, year = {1988}, note = {J Magn ResonQ6187Times Cited:10Cited References Count:33}, month = {Oct 15}, pages = {96-111}, isbn = {0022-2364}, doi = {Doi 10.1016/0022-2364(88)90060-1}, url = {://WOS:A1988Q618700008}, author = {Shaka, A. J. and Shykind, D. N. and Chingas, G. C. and Pines, A.} } @article {558, title = {Observation of Molecular-Reorientation in Ice by Proton and Deuterium Magnetic-Resonance}, journal = {Journal of the American Chemical Society}, volume = {110}, year = {1988}, note = {J Am Chem SocP7649Times Cited:80Cited References Count:16}, month = {Aug 17}, pages = {5668-5671}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja00225a013}, url = {://WOS:A1988P764900013}, author = {Wittebort, R. J. and Usha, M. G. and Ruben, D. J. and Wemmer, D. E. and Pines, A.} } @article {561, title = {Phase-Incremented Multiple-Quantum Nmr Experiments}, journal = {Journal of Magnetic Resonance}, volume = {76}, year = {1988}, note = {J Magn ResonL9552Times Cited:49Cited References Count:17}, month = {Jan}, pages = {149-154}, isbn = {0022-2364}, doi = {Doi 10.1016/0022-2364(88)90209-0}, url = {://WOS:A1988L955200015}, author = {Shykind, D. N. and Baum, J. and Liu, S. B. and Pines, A.} } @article {569, title = {Probing Metal Cluster Formation in Nay Zeolite by Xe-129 Nmr}, journal = {Journal of the American Chemical Society}, volume = {110}, year = {1988}, note = {J Am Chem SocP0739Times Cited:33Cited References Count:18}, month = {Jun 22}, pages = {4465-4467}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja00221a086}, url = {://WOS:A1988P073900086}, author = {Chmelka, B. F. and Ryoo, R. and Liu, S. B. and Demenorval, L. C. and Radke, C. J. and Petersen, E. E. and Pines, A.} } @article {567, title = {A Si-29 Nuclear Magnetic-Resonance Study of Silicon-Aluminum Ordering in Leucite and Analcite}, journal = {Physics and Chemistry of Minerals}, volume = {15}, year = {1988}, note = {Phys Chem MinerM6832Times Cited:44Cited References Count:39}, pages = {370-382}, isbn = {0342-1791}, doi = {Doi 10.1007/Bf00311042}, url = {://WOS:A1988M683200009}, author = {Murdoch, J. B. and Stebbins, J. F. and Carmichael, I. S. E. and Pines, A.} } @article {560, title = {Study of the Aharonov-Anandan Quantum Phase by Nmr Interferometry}, journal = {Physical Review Letters}, volume = {60}, year = {1988}, note = {Phys Rev LettM6160Times Cited:184Cited References Count:43}, month = {Mar 28}, pages = {1218-1220}, isbn = {0031-9007}, doi = {Doi 10.1103/Physrevlett.60.1218}, url = {://WOS:A1988M616000003}, author = {Suter, D. and Mueller, K. T. and Pines, A.} } @article {592, title = {Assignment of Dipolar Couplings and Estimation of Conformational Probabilities in Partially Oriented Hexane}, journal = {Chemical Physics Letters}, volume = {137}, year = {1987}, note = {Chem Phys LettH6843Times Cited:19Cited References Count:19}, month = {May 29}, pages = {51-56}, isbn = {0009-2614}, doi = {Doi 10.1016/0009-2614(87)80303-2}, url = {://WOS:A1987H684300012}, author = {Gochin, M. and Zimmermann, H. and Pines, A.} } @article {579, title = {Berry Phase in Magnetic-Resonance}, journal = {Molecular Physics}, volume = {61}, year = {1987}, note = {Mol PhysK2154Times Cited:90Cited References Count:47}, month = {Aug 20}, pages = {1327-1340}, isbn = {0026-8976}, doi = {Doi 10.1080/00268978700101831}, url = {://WOS:A1987K215400001}, author = {Suter, D. and Chingas, G. C. and Harris, R. A. and Pines, A.} } @article {582, title = {Broad-Band Heteronuclear Decoupling in the Presence of Homonuclear Dipolar and Quadrupolar Interactions}, journal = {Journal of Magnetic Resonance}, volume = {73}, year = {1987}, note = {J Magn ResonH7285Times Cited:40Cited References Count:31}, month = {Jun 1}, pages = {99-113}, isbn = {0022-2364}, doi = {Doi 10.1016/0022-2364(87)90228-9}, url = {://WOS:A1987H728500009}, author = {Schenker, K. V. and Suter, D. and Pines, A.} } @article {583, title = {Distribution of Hexamethylbenzene in a Zeolite Studied by Xe-129 and Multiple-Quantum Nmr}, journal = {Journal of Physical Chemistry}, volume = {91}, year = {1987}, note = {J Phys Chem-UsL6632Times Cited:63Cited References Count:16}, month = {Dec 31}, pages = {6575-6577}, isbn = {0022-3654}, doi = {Doi 10.1021/J100311a003}, url = {://WOS:A1987L663200003}, author = {Ryoo, R. and Liu, S. B. and Demenorval, L. C. and Takegoshi, K. and Chmelka, B. and Trecoske, M. and Pines, A.} } @article {591, title = {Effect of Correlated Proton Jumps on the Zero-Field Nmr-Spectrum of Solid P-Toluic Acid}, journal = {Journal of Physical Chemistry}, volume = {91}, year = {1987}, note = {J Phys Chem-UsH0705Times Cited:15Cited References Count:14}, month = {Apr 23}, pages = {2240-2242}, isbn = {0022-3654}, doi = {Doi 10.1021/J100293a006}, url = {://WOS:A1987H070500006}, author = {Jarvie, T. P. and Thayer, A. M. and Millar, J. M. and Pines, A.} } @article {573, title = {Heteronuclear Zero-Field Nmr of Liquid-Crystals}, journal = {Journal of Magnetic Resonance}, volume = {72}, year = {1987}, note = {J Magn ResonH2852Times Cited:1Cited References Count:13}, month = {May}, pages = {567-573}, isbn = {0022-2364}, doi = {Doi 10.1016/0022-2364(87)90164-8}, url = {://WOS:A1987H285200020}, author = {Thayer, A. M. and Luzar, M. and Pines, A.} } @article {594, title = {Iterative Maps for Broad-Band Excitation of Transverse Coherence in 2 Level Systems}, journal = {Journal of Chemical Physics}, volume = {86}, year = {1987}, note = {J Chem PhysH7665Times Cited:6Cited References Count:38}, month = {Jun 15}, pages = {6591-6601}, isbn = {0021-9606}, doi = {Doi 10.1063/1.452405}, url = {://WOS:A1987H766500003}, author = {Cho, H. and Pines, A.} } @article {595, title = {Iterative Maps with Multiple Fixed-Points for Excitation of 2 Level Systems}, journal = {Journal of Chemical Physics}, volume = {86}, year = {1987}, note = {J Chem PhysG4424Times Cited:12Cited References Count:68}, month = {Mar 15}, pages = {3089-3106}, isbn = {0021-9606}, doi = {Doi 10.1063/1.452020}, url = {://WOS:A1987G442400004}, author = {Cho, H. and Baum, J. and Pines, A.} } @article {577, title = {Multiple Quantum Nmr Excitation with a One-Quantum Hamiltonian}, journal = {Chemical Physics}, volume = {114}, year = {1987}, note = {Chem PhysH4338Times Cited:45Cited References Count:16}, month = {May 15}, pages = {103-109}, isbn = {0301-0104}, doi = {Doi 10.1016/0301-0104(87)80023-X}, url = {://WOS:A1987H433800010}, author = {Suter, D. and Liu, S. B. and Baum, J. and Pines, A.} } @article {584, title = {Multiple-Quantum Dynamics in Nmr - a Directed Walk through Liouville Space}, journal = {Journal of Chemical Physics}, volume = {86}, year = {1987}, note = {J Chem PhysG4424Times Cited:72Cited References Count:24}, month = {Mar 15}, pages = {3172-3182}, isbn = {0021-9606}, doi = {Doi 10.1063/1.452028}, url = {://WOS:A1987G442400012}, author = {Munowitz, M. and Pines, A. and Mehring, M.} } @article {574, title = {Multiple-Quantum Nmr-Study on Correlation of 2 Methyl-Groups}, journal = {Scientia Sinica Series a-Mathematical Physical Astronomical \& Technical Sciences}, volume = {30}, year = {1987}, note = {Sci China Ser AG8059Times Cited:2Cited References Count:12}, month = {Feb}, pages = {157-164}, url = {://WOS:A1987G805900005}, author = {Tang, J. and Wang, J. F. and Pines, A.} } @article {578, title = {Observation of Spin Diffusion in Zero-Field Magnetic-Resonance}, journal = {Physical Review Letters}, volume = {59}, year = {1987}, note = {Phys Rev LettH9613Times Cited:4Cited References Count:15}, month = {Jul 6}, pages = {106-108}, isbn = {0031-9007}, doi = {Doi 10.1103/Physrevlett.59.106}, url = {://WOS:A1987H961300028}, author = {Suter, D. and Jarvie, T. P. and Sun, B. and Pines, A.} } @article {596, title = {Pake Patterns from Zero to High-Field}, journal = {Journal of Magnetic Resonance}, volume = {74}, year = {1987}, note = {J Magn ResonK2008Times Cited:2Cited References Count:17}, month = {Sep}, pages = {381-385}, isbn = {0022-2364}, doi = {Doi 10.1016/0022-2364(87)90349-0}, url = {://WOS:A1987K200800016}, author = {Bielecki, A. and Pines, A.} } @article {585, title = {Principles and Applications of Multiple-Quantum Nmr}, journal = {Advances in Chemical Physics}, volume = {66}, year = {1987}, note = {Adv Chem PhysF9398Times Cited:113Cited References Count:286}, pages = {1-152}, isbn = {0065-2385}, url = {://WOS:A1987F939800001}, author = {Munowitz, M. and Pines, A.} } @article {587, title = {Quenching of Residual Fields by Nonaxially Symmetrical Dipolar Coupling in Zero-Field Nmr}, journal = {Journal of Magnetic Resonance}, volume = {73}, year = {1987}, note = {J Magn ResonJ1554Times Cited:1Cited References Count:22}, month = {Jul}, pages = {459-466}, isbn = {0022-2364}, doi = {Doi 10.1016/0022-2364(87)90008-4}, url = {://WOS:A1987J155400008}, author = {Luzar, M. and Thayer, A. M. and Pines, A.} } @article {576, title = {Recursive Evaluation of Interaction Pictures}, journal = {Journal of Magnetic Resonance}, volume = {75}, year = {1987}, note = {J Magn ResonL8015Times Cited:1Cited References Count:8}, month = {Dec}, pages = {509-512}, isbn = {0022-2364}, doi = {Doi 10.1016/0022-2364(87)90106-5}, url = {://WOS:A1987L801500011}, author = {Suter, D. and Pines, A.} } @article {589, title = {Relaxation Mechanisms and Effects of Motion in Albite (Naalsi3o8) Liquid and Glass - a High-Temperature Nmr-Study}, journal = {Physics and Chemistry of Minerals}, volume = {15}, year = {1987}, note = {Phys Chem MinerL0167Times Cited:40Cited References Count:57}, pages = {155-162}, isbn = {0342-1791}, doi = {Doi 10.1007/Bf00308778}, url = {://WOS:A1987L016700007}, author = {Liu, S. B. and Pines, A. and Brandriss, M. and Stebbins, J. F.} } @article {581, title = {Speciation and Local-Structure in Alkali and Alkaline-Earth Silicate-Glasses - Constraints from Si-29 Nmr-Spectroscopy}, journal = {Journal of Non-Crystalline Solids}, volume = {89}, year = {1987}, note = {J Non-Cryst SolidsG5155Times Cited:74Cited References Count:46}, month = {Mar}, pages = {371-383}, isbn = {0022-3093}, doi = {Doi 10.1016/S0022-3093(87)80279-X}, url = {://WOS:A1987G515500011}, author = {Schneider, E. and Stebbins, J. F. and Pines, A.} } @article {580, title = {Symmetrical Phase-Alternating Composite Pulses}, journal = {Journal of Magnetic Resonance}, volume = {71}, year = {1987}, note = {J Magn ResonG3693Times Cited:74Cited References Count:28}, month = {Feb 15}, pages = {495-503}, isbn = {0022-2364}, doi = {Doi 10.1016/0022-2364(87)90249-6}, url = {://WOS:A1987G369300009}, author = {Shaka, A. J. and Pines, A.} } @article {575, title = {Theory of Broad-Band Heteronuclear Decoupling in Multispin Systems}, journal = {Journal of Magnetic Resonance}, volume = {73}, year = {1987}, note = {J Magn ResonH7285Times Cited:23Cited References Count:6}, month = {Jun 1}, pages = {90-98}, isbn = {0022-2364}, doi = {Doi 10.1016/0022-2364(87)90227-7}, url = {://WOS:A1987H728500008}, author = {Suter, D. and Schenker, K. V. and Pines, A.} } @article {586, title = {Theory of Line-Shapes for Zero-Field Nmr in the Presence of Molecular-Motion}, journal = {Journal of Chemical Physics}, volume = {87}, year = {1987}, note = {J Chem PhysL1661Times Cited:10Cited References Count:41}, month = {Dec 15}, pages = {6867-6876}, isbn = {0021-9606}, doi = {Doi 10.1063/1.453381}, url = {://WOS:A1987L166100011}, author = {Meier, P. and Kothe, G. and Jonsen, P. and Trecoske, M. and Pines, A.} } @article {590, title = {Theory of Multiple-Pulse Nmr at Low and Zero Fields}, journal = {Journal of Magnetic Resonance}, volume = {75}, year = {1987}, note = {J Magn ResonK7509Times Cited:14Cited References Count:18}, month = {Oct 15}, pages = {110-124}, isbn = {0022-2364}, doi = {Doi 10.1016/0022-2364(87)90318-0}, url = {://WOS:A1987K750900010}, author = {Lee, C. J. and Suter, D. and Pines, A.} } @article {593, title = {Two-Dimensional Multiple Quantum Nmr of Isotopic Mixtures in Liquid-Crystals}, journal = {Molecular Physics}, volume = {60}, year = {1987}, note = {Mol PhysF9930Times Cited:12Cited References Count:18}, month = {Jan}, pages = {205-212}, isbn = {0026-8976}, doi = {Doi 10.1080/00268978700100151}, url = {://WOS:A1987F993000015}, author = {Gochin, M. and Hugicleary, D. and Zimmermann, H. and Pines, A.} } @article {570, title = {Zero-Field Nmr}, journal = {Accounts of Chemical Research}, volume = {20}, year = {1987}, note = {Accounts Chem ResG2724Times Cited:35Cited References Count:39}, month = {Feb}, pages = {47-53}, isbn = {0001-4842}, doi = {Doi 10.1021/Ar00134a001}, url = {://WOS:A1987G272400001}, author = {Thayer, A. M. and Pines, A.} } @article {572, title = {Zero-Field Nmr of Nematic Liquid-Crystals with Positive and Negative Magnetic-Susceptibility Anisotropies}, journal = {Journal of Physical Chemistry}, volume = {91}, year = {1987}, note = {J Phys Chem-UsG8355Times Cited:4Cited References Count:22}, month = {Apr 9}, pages = {2194-2197}, isbn = {0022-3654}, doi = {Doi 10.1021/J100292a043}, url = {://WOS:A1987G835500043}, author = {Thayer, A. M. and Luzar, M. and Pines, A.} } @article {588, title = {Zero-Field Nmr of Uniaxial and Biaxial Smectic Liquid-Crystals}, journal = {Molecular Physics}, volume = {62}, year = {1987}, note = {Mol PhysL0770Times Cited:2Cited References Count:30}, month = {Oct 20}, pages = {573-583}, isbn = {0026-8976}, doi = {Doi 10.1080/00268978700102411}, url = {://WOS:A1987L077000003}, author = {Luzar, M. and Thayer, A. M. and Pines, A.} } @article {571, title = {Zero-Field Nmr-Study of the Biaxial Smectic-E Phase}, journal = {Liquid Crystals}, volume = {2}, year = {1987}, note = {Liq CrystH5818Times Cited:3Cited References Count:12}, month = {Mar-Apr}, pages = {241-244}, isbn = {0267-8292}, doi = {Doi 10.1080/02678298708086296}, url = {://WOS:A1987H581800012}, author = {Thayer, A. M. and Luzar, M. and Pines, A.} } @article {604, title = {Book review of Solid State NMR for Chemists by Colin J. Fyfe}, journal = {Journal of the American Chemical Society}, year = {1986}, pages = {5373}, author = {Pines, A.} } @article {598, title = {Composite Pulses in Zero-Field Nmr}, journal = {Journal of Magnetic Resonance}, volume = {70}, year = {1986}, note = {J Magn ResonF4381Times Cited:8Cited References Count:33}, month = {Dec}, pages = {518-522}, isbn = {0022-2364}, doi = {Doi 10.1016/0022-2364(86)90147-2}, url = {://WOS:A1986F438100023}, author = {Thayer, A. M. and Pines, A.} } @article {603, title = {Defects and Short-Range Order in Nepheline Group Minerals - a Si-29 Nuclear-Magnetic-Resonance Study}, journal = {Physics and Chemistry of Minerals}, volume = {13}, year = {1986}, note = {Phys Chem MinerE6311Times Cited:40Cited References Count:61}, pages = {371-381}, isbn = {0342-1791}, url = {://WOS:A1986E631100003}, author = {Stebbins, J. F. and Murdoch, J. B. and Carmichael, I. S. E. and Pines, A.} } @article {609, title = {Determination of Dipole Dipole Couplings in Oriented Normal-Hexane by Two-Dimensional Nmr}, journal = {Journal of the American Chemical Society}, volume = {108}, year = {1986}, note = {J Am Chem SocE5180Times Cited:22Cited References Count:17}, month = {Oct 15}, pages = {6813-6814}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja00281a064}, url = {://WOS:A1986E518000064}, author = {Gochin, M. and Schenker, K. V. and Zimmermann, H. and Pines, A.} } @article {606, title = {High-Resolution Studies of Deuterium by Time-Domain Zero-Field Nqr}, journal = {Journal of Magnetic Resonance}, volume = {69}, year = {1986}, note = {J Magn ResonE1115Times Cited:11Cited References Count:49}, month = {Sep}, pages = {243-257}, isbn = {1090-7807}, doi = {Doi 10.1016/0022-2364(86)90076-4}, url = {://WOS:A1986E111500005}, author = {Millar, J. M. and Thayer, A. M. and Zimmermann, H. and Pines, A.} } @article {601, title = {Indirect Phase Detection of Nmr Spinor Transitions}, journal = {Physical Review Letters}, volume = {57}, year = {1986}, note = {Phys Rev LettD1256Times Cited:13Cited References Count:11}, month = {Jul 14}, pages = {242-244}, isbn = {0031-9007}, doi = {Doi 10.1103/Physrevlett.57.242}, url = {://WOS:A1986D125600022}, author = {Suter, D. and Pines, A. and Mehring, M.} } @article {611, title = {Iterative Maps for Bistable Excitation of 2-Level Systems}, journal = {Physical Review Letters}, volume = {56}, year = {1986}, note = {Phys Rev LettC1114Times Cited:23Cited References Count:21}, month = {May 5}, pages = {1905-1908}, isbn = {0031-9007}, doi = {Doi 10.1103/Physrevlett.56.1905}, url = {://WOS:A1986C111400006}, author = {Cho, H. M. and Tycko, R. and Pines, A. and Guckenheimer, J.} } @article {610, title = {Multiple Quantum Spectrum of Oriented Hexane-D6}, journal = {Chemical Physics}, volume = {108}, year = {1986}, note = {Chem PhysE1754Times Cited:7Cited References Count:27}, month = {Oct 1}, pages = {179-185}, isbn = {0301-0104}, doi = {Doi 10.1016/0301-0104(86)85039-X}, url = {://WOS:A1986E175400001}, author = {Drobny, G. and Weitekamp, D. P. and Pines, A.} } @article {616, title = {Multiple-Quantum Nmr-Study of Clustering in Hydrogenated Amorphous-Silicon}, journal = {Physical Review Letters}, volume = {56}, year = {1986}, note = {Phys Rev LettA6285Times Cited:157Cited References Count:13}, month = {Mar 31}, pages = {1377-1380}, isbn = {0031-9007}, doi = {Doi 10.1103/Physrevlett.56.1377}, url = {://WOS:A1986A628500016}, author = {Baum, J. and Gleason, K. K. and Pines, A. and Garroway, A. N. and Reimer, J. A.} } @article {605, title = {Multiple-Quantum Nuclear-Magnetic-Resonance Spectroscopy}, journal = {Science}, volume = {233}, year = {1986}, note = {ScienceD3391Times Cited:50Cited References Count:59}, month = {Aug 1}, pages = {525-531}, isbn = {0036-8075}, doi = {Doi 10.1126/Science.233.4763.525}, url = {://WOS:A1986D339100022}, author = {Munowitz, M. and Pines, A.} } @article {602, title = {New Probe for High-Temperature Nmr-Spectroscopy with Ppm Resolution}, journal = {Review of Scientific Instruments}, volume = {57}, year = {1986}, note = {Rev Sci InstrumAxa20Times Cited:15Cited References Count:19}, month = {Jan}, pages = {39-42}, isbn = {0034-6748}, doi = {Doi 10.1063/1.1139115}, url = {://WOS:A1986AXA2000010}, author = {Stebbins, J. F. and Schneider, E. and Murdoch, J. B. and Pines, A. and Carmichael, I. S. E.} } @article {615, title = {Nmr-Studies of Clustering in Solids}, journal = {Journal of the American Chemical Society}, volume = {108}, year = {1986}, note = {J Am Chem SocF0090Times Cited:114Cited References Count:28}, month = {Nov 26}, pages = {7447-7454}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja00284a001}, url = {://WOS:A1986F009000001}, author = {Baum, J. and Pines, A.} } @article {614, title = {Spatially Selective Nmr with Broad-Band Radiofrequency Pulses}, journal = {Chemical Physics}, volume = {105}, year = {1986}, note = {Chem PhysC7043Times Cited:6Cited References Count:47}, month = {Jun 1}, pages = {7-14}, isbn = {0301-0104}, doi = {Doi 10.1016/0301-0104(86)80051-9}, url = {://WOS:A1986C704300002}, author = {Baum, J. and Tycko, R. and Pines, A.} } @article {608, title = {Theory of Chemical-Exchange in Zero-Field Nmr - 2-Site Flips}, journal = {Journal of Chemical Physics}, volume = {85}, year = {1986}, note = {J Chem PhysE5176Times Cited:9Cited References Count:13}, month = {Nov 1}, pages = {4873-4880}, isbn = {0021-9606}, doi = {Doi 10.1063/1.451722}, url = {://WOS:A1986E517600014}, author = {Jonsen, P. and Luzar, M. and Pines, A. and Mehring, M.} } @article {613, title = {Time Domain Zero-Field Nmr and Nqr}, journal = {Zeitschrift Fur Naturforschung Section a-a Journal of Physical Sciences}, volume = {41}, year = {1986}, note = {Z Naturforsch AA6350Times Cited:2Cited References Count:22}, month = {Jan-Feb}, pages = {440-444}, isbn = {0932-0784}, url = {://WOS:A1986A635000084}, author = {Bielecki, A. and Zax, D. B. and Thayer, A. M. and Millar, J. M. and Pines, A.} } @article {599, title = {Two-Dimensional Zero-Field Nmr and Nqr}, journal = {Chemical Physics Letters}, volume = {129}, year = {1986}, note = {Chem Phys LettD7200Times Cited:16Cited References Count:24}, month = {Aug 15}, pages = {55-58}, isbn = {0009-2614}, doi = {Doi 10.1016/0009-2614(86)80167-1}, url = {://WOS:A1986D720000011}, author = {Thayer, A. M. and Millar, J. M. and Pines, A.} } @article {612, title = {Zero-Field Nmr and Nqr Spectrometer}, journal = {Review of Scientific Instruments}, volume = {57}, year = {1986}, note = {Rev Sci InstrumA7607Times Cited:42Cited References Count:59}, month = {Mar}, pages = {393-403}, isbn = {0034-6748}, doi = {Doi 10.1063/1.1138898}, url = {://WOS:A1986A760700017}, author = {Bielecki, A. and Zax, D. B. and Zilm, K. W. and Pines, A.} } @article {607, title = {Zero-Field Nmr of Small-Amplitude Motions in a Polycrystalline Solid}, journal = {Journal of the American Chemical Society}, volume = {108}, year = {1986}, note = {J Am Chem SocD7238Times Cited:22Cited References Count:21}, month = {Aug 20}, pages = {5113-5116}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja00277a012}, url = {://WOS:A1986D723800012}, author = {Millar, J. M. and Thayer, A. M. and Zax, D. B. and Pines, A.} } @article {597, title = {Zero-Field Nmr of Solid Bis(Mu-Hydrido)Decacarbonyltriosmium}, journal = {Journal of Physical Chemistry}, volume = {90}, year = {1986}, note = {J Phys Chem-UsA5026Times Cited:5Cited References Count:26}, month = {Mar 13}, pages = {1065-1069}, isbn = {0022-3654}, doi = {Doi 10.1021/J100278a021}, url = {://WOS:A1986A502600021}, author = {Zax, D. B. and Bielecki, A. and Kulzick, M. A. and Muetterties, E. L. and Pines, A.} } @article {600, title = {Zero-Field Nuclear-Magnetic-Resonance of a Nematic Liquid-Crystal}, journal = {Journal of Physical Chemistry}, volume = {90}, year = {1986}, note = {J Phys Chem-UsA8609Times Cited:10Cited References Count:32}, month = {Apr 10}, pages = {1577-1581}, isbn = {0022-3654}, doi = {Doi 10.1021/J100399a024}, url = {://WOS:A1986A860900024}, author = {Thayer, A. M. and Millar, J. M. and Luzar, M. and Jarvie, T. P. and Pines, A.} } @article {624, title = {Broad-Band and Adiabatic Inversion of a 2-Level System by Phase-Modulated Pulses}, journal = {Physical Review A}, volume = {32}, year = {1985}, note = {Phys Rev AAvc77Times Cited:227Cited References Count:35}, pages = {3435-3447}, isbn = {1050-2947}, doi = {Doi 10.1103/Physreva.32.3435}, url = {://WOS:A1985AVC7700029}, author = {Baum, J. and Tycko, R. and Pines, A.} } @article {619, title = {Composite Pulses without Phase-Distortion}, journal = {Journal of Magnetic Resonance}, volume = {61}, year = {1985}, note = {J Magn ResonAbv11Times Cited:124Cited References Count:37}, pages = {90-101}, isbn = {1090-7807}, doi = {Doi 10.1016/0022-2364(85)90270-7}, url = {://WOS:A1985ABV1100009}, author = {Tycko, R. and Cho, H. M. and Schneider, E. and Pines, A.} } @article {618, title = {Fixed-Point Theory of Iterative Excitation Schemes in Nmr}, journal = {Journal of Chemical Physics}, volume = {83}, year = {1985}, note = {J Chem PhysAqw58Times Cited:126Cited References Count:72}, pages = {2775-2802}, isbn = {0021-9606}, doi = {Doi 10.1063/1.449228}, url = {://WOS:A1985AQW5800020}, author = {Tycko, R. and Pines, A. and Guckenheimer, J.} } @article {623, title = {High-Resolution Nmr with a Surface Coil}, journal = {Journal of the American Chemical Society}, volume = {107}, year = {1985}, note = {J Am Chem SocAvb48Times Cited:6Cited References Count:18}, pages = {7193-7194}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja00310a082}, url = {://WOS:A1985AVB4800082}, author = {Gochin, M. and Pines, A.} } @article {620, title = {A High-Temperature High-Resolution Nmr-Study of Na-23, Al-27 and Si-29 in Molten Silicates}, journal = {Nature}, volume = {314}, year = {1985}, note = {NatureAdt99Times Cited:58Cited References Count:13}, pages = {250-252}, isbn = {0028-0836}, doi = {Doi 10.1038/314250a0}, url = {://WOS:A1985ADT9900039}, author = {Stebbins, J. F. and Murdoch, J. B. and Schneider, E. and Carmichael, I. S. E. and Pines, A.} } @article {625, title = {Multiple-Quantum Dynamics in Solid-State Nmr}, journal = {Journal of Chemical Physics}, volume = {83}, year = {1985}, note = {J Chem PhysAqg37Times Cited:212Cited References Count:53}, pages = {2015-2025}, isbn = {0021-9606}, doi = {Doi 10.1063/1.449344}, url = {://WOS:A1985AQG3700002}, author = {Baum, J. and Munowitz, M. and Garroway, A. N. and Pines, A.} } @article {622, title = {A Sharp Method for High-Resolution Nmr of Heteronuclear Spin Systems in Inhomogeneous Fields}, journal = {Journal of Magnetic Resonance}, volume = {63}, year = {1985}, note = {J Magn ResonAmg38Times Cited:18Cited References Count:30}, pages = {431-437}, isbn = {1090-7807}, doi = {Doi 10.1016/0022-2364(85)90341-5}, url = {://WOS:A1985AMG3800028}, author = {Gochin, M. and Weitekamp, D. P. and Pines, A.} } @article {617, title = {Zero-Field Nmr and Nqr}, journal = {Journal of Chemical Physics}, volume = {83}, year = {1985}, note = {J Chem PhysAtt21Times Cited:105Cited References Count:184}, pages = {4877-4905}, isbn = {0021-9606}, doi = {Doi 10.1063/1.449748}, url = {://WOS:A1985ATT2100005}, author = {Zax, D. B. and Bielecki, A. and Zilm, K. W. and Pines, A. and Weitekamp, D. P.} } @article {621, title = {Zero-Field Nmr and Nqr with Selective Pulses and Indirect Detection}, journal = {Journal of Chemical Physics}, volume = {83}, year = {1985}, note = {J Chem PhysAmg31Times Cited:36Cited References Count:31}, pages = {934-938}, isbn = {0021-9606}, doi = {Doi 10.1063/1.449419}, url = {://WOS:A1985AMG3100004}, author = {Millar, J. M. and Thayer, A. M. and Bielecki, A. and Zax, D. B. and Pines, A.} } @article {629, title = {Broad-Band Population-Inversion in Solid-State Nmr}, journal = {Journal of Chemical Physics}, volume = {81}, year = {1984}, note = {J Chem PhysTb783Times Cited:50Cited References Count:41}, pages = {680-688}, isbn = {0021-9606}, doi = {Doi 10.1063/1.447749}, url = {://WOS:A1984TB78300012}, author = {Tycko, R. and Schneider, E. and Pines, A.} } @article {633, title = {Computer-Simulations of Multiple-Quantum Nmr Experiments .1. Nonselective Excitation}, journal = {Journal of Magnetic Resonance}, volume = {60}, year = {1984}, note = {J Magn ResonTw096Times Cited:58Cited References Count:50}, pages = {205-235}, isbn = {1090-7807}, doi = {Doi 10.1016/0022-2364(84)90327-5}, url = {://WOS:A1984TW09600005}, author = {Murdoch, J. B. and Warren, W. S. and Weitekamp, D. P. and Pines, A.} } @article {628, title = {Computer-Simulations of Multiple-Quantum Nmr Experiments .2. Selective Excitation}, journal = {Journal of Magnetic Resonance}, volume = {60}, year = {1984}, note = {J Magn ResonTw096Times Cited:11Cited References Count:23}, pages = {236-256}, isbn = {1090-7807}, doi = {Doi 10.1016/0022-2364(84)90328-7}, url = {://WOS:A1984TW09600006}, author = {Warren, W. S. and Murdoch, J. B. and Pines, A.} } @article {627, title = {Differentiation between Al-27 Nuclei in Alums by Fourier-Transform Pure Nuclear-Quadrupole Resonance}, journal = {Nature}, volume = {312}, year = {1984}, note = {NatureTt555Times Cited:17Cited References Count:12}, pages = {351-352}, isbn = {0028-0836}, doi = {Doi 10.1038/312351a0}, url = {://WOS:A1984TT55500046}, author = {Zax, D. B. and Bielecki, A. and Pines, A. and Sinton, S. W.} } @article {635, title = {Fourier-Transform Pure Nuclear-Quadrupole Resonance by Pulsed Field Cycling}, journal = {Journal of Chemical Physics}, volume = {80}, year = {1984}, note = {J Chem PhysSh432Times Cited:34Cited References Count:23}, pages = {2232-2234}, isbn = {0021-9606}, doi = {Doi 10.1063/1.446915}, url = {://WOS:A1984SH43200068}, author = {Bielecki, A. and Murdoch, J. B. and Weitekamp, D. P. and Zax, D. B. and Zilm, K. W. and Zimmermann, H. and Pines, A.} } @article {626, title = {Heteronuclear Zero-Field Nmr}, journal = {Chemical Physics Letters}, volume = {106}, year = {1984}, note = {Chem Phys LettSt870Times Cited:16Cited References Count:9}, pages = {550-553}, isbn = {0009-2614}, doi = {Doi 10.1016/0009-2614(84)85381-6}, url = {://WOS:A1984ST87000014}, author = {Zax, D. B. and Bielecki, A. and Zilm, K. W. and Pines, A.} } @article {631, title = {Iterative Schemes for Broad-Band and Narrow-Band Population-Inversion in Nmr}, journal = {Chemical Physics Letters}, volume = {111}, year = {1984}, note = {Chem Phys LettTu813Times Cited:50Cited References Count:18}, pages = {462-467}, isbn = {0009-2614}, doi = {Doi 10.1016/0009-2614(84)85541-4}, url = {://WOS:A1984TU81300031}, author = {Tycko, R. and Pines, A.} } @article {632, title = {Multiple-Quantum Nmr-Study of Molecular-Structure and Ordering in a Liquid-Crystal}, journal = {Molecular Physics}, volume = {53}, year = {1984}, note = {Mol PhysTq351Times Cited:65Cited References Count:45}, pages = {333-362}, isbn = {0026-8976}, doi = {Doi 10.1080/00268978400102351}, url = {://WOS:A1984TQ35100007}, author = {Sinton, S. W. and Zax, D. B. and Murdoch, J. B. and Pines, A.} } @article {634, title = {Nmr Imaging in Solids by Multiple-Quantum Resonance}, journal = {Journal of Magnetic Resonance}, volume = {60}, year = {1984}, note = {J Magn ResonTw096Times Cited:79Cited References Count:24}, pages = {337-341}, isbn = {1090-7807}, doi = {Doi 10.1016/0022-2364(84)90336-6}, url = {://WOS:A1984TW09600014}, author = {Garroway, A. N. and Baum, J. and Munowitz, M. G. and Pines, A.} } @article {630, title = {Spatial Localization of Nmr Signals by Narrowband Inversion}, journal = {Journal of Magnetic Resonance}, volume = {60}, year = {1984}, note = {J Magn ResonTs255Times Cited:66Cited References Count:26}, pages = {156-160}, isbn = {1090-7807}, doi = {Doi 10.1016/0022-2364(84)90042-8}, url = {://WOS:A1984TS25500022}, author = {Tycko, R. and Pines, A.} } @article {643, title = {Broad-Band Population-Inversion by Phase Modulated Pulses}, journal = {Journal of Chemical Physics}, volume = {79}, year = {1983}, note = {J Chem PhysRn512Times Cited:89Cited References Count:13}, pages = {4643-4644}, isbn = {0021-9606}, doi = {Doi 10.1063/1.446381}, url = {://WOS:A1983RN51200071}, author = {Baum, J. and Tycko, R. and Pines, A.} } @article {638, title = {Multiple quantum NMR spectroscopy}, journal = {Chinese Journal of Microwave and Radio Frequency Spectroscopy}, volume = {1}, year = {1983}, pages = {12}, author = {Ye, C. and Tang, J. and Pines, A.} } @article {637, title = {Multiple-Quantum Nmr in Solids}, journal = {Journal of Chemical Physics}, volume = {78}, year = {1983}, note = {J Chem PhysQg963Times Cited:107Cited References Count:15}, pages = {3579-3582}, isbn = {0021-9606}, doi = {Doi 10.1063/1.445185}, url = {://WOS:A1983QG96300031}, author = {Yen, Y. S. and Pines, A.} } @article {639, title = {Spin Diffusion and Orientation Dependence of Deuterium T1 in Solids}, journal = {Journal of Magnetic Resonance}, volume = {55}, year = {1983}, note = {J Magn ResonRr923Times Cited:10Cited References Count:7}, pages = {334-337}, isbn = {1090-7807}, doi = {Doi 10.1016/0022-2364(83)90245-7}, url = {://WOS:A1983RR92300016}, author = {Ye, C. and Eckman, R. and Pines, A.} } @article {642, title = {Spin Diffusion between Inequivalent Quadrupolar Nuclei by Double-Quantum Flip-Flops}, journal = {Chemical Physics Letters}, volume = {99}, year = {1983}, note = {Chem Phys LettRb604Times Cited:13Cited References Count:13}, pages = {35-40}, isbn = {0009-2614}, doi = {Doi 10.1016/0009-2614(83)80265-6}, url = {://WOS:A1983RB60400008}, author = {Eckman, R. and Pines, A. and Tycko, R. and Weitekamp, D. P.} } @article {636, title = {Study of Anisotropic Diffusion of Oriented Molecules by Multiple Quantum Spin Echoes}, journal = {Journal of Chemical Physics}, volume = {78}, year = {1983}, note = {J Chem PhysQn789Times Cited:66Cited References Count:17}, pages = {6333-6334}, isbn = {0021-9606}, doi = {Doi 10.1063/1.444559}, url = {://WOS:A1983QN78900060}, author = {Zax, D. and Pines, A.} } @article {641, title = {Total Spin Coherence Transfer Echo Spectroscopy}, journal = {Journal of Chemical Physics}, volume = {79}, year = {1983}, note = {J Chem PhysRr565Times Cited:25Cited References Count:43}, pages = {5301-5310}, isbn = {0021-9606}, doi = {Doi 10.1063/1.445692}, url = {://WOS:A1983RR56500011}, author = {Garbow, J. R. and Weitekamp, D. P. and Pines, A.} } @article {640, title = {Zero-Field Nuclear Magnetic-Resonance}, journal = {Physical Review Letters}, volume = {50}, year = {1983}, note = {Phys Rev LettQr621Times Cited:103Cited References Count:21}, pages = {1807-1810}, isbn = {0031-9007}, doi = {Doi 10.1103/Physrevlett.50.1807}, url = {://WOS:A1983QR62100025}, author = {Weitekamp, D. P. and Bielecki, A. and Zax, D. and Zilm, K. and Pines, A.} } @article {648, title = {Bilinear Rotation Decoupling of Homonuclear Scalar Interactions}, journal = {Chemical Physics Letters}, volume = {93}, year = {1982}, note = {Chem Phys LettPw861Times Cited:358Cited References Count:22}, pages = {504-509}, isbn = {0009-2614}, doi = {Doi 10.1016/0009-2614(82)83229-6}, url = {://WOS:A1982PW86100020}, author = {Garbow, J. R. and Weitekamp, D. P. and Pines, A.} } @article {645, title = {Determination of Dipole Coupling-Constants Using Heteronuclear Multiple Quantum Nmr}, journal = {Journal of Chemical Physics}, volume = {77}, year = {1982}, note = {J Chem PhysPf412Times Cited:119Cited References Count:44}, pages = {2870-2883}, isbn = {0021-9606}, doi = {Doi 10.1063/1.444180}, url = {://WOS:A1982PF41200024}, author = {Weitekamp, D. P. and Garbow, J. R. and Pines, A.} } @article {644, title = {Search Procedure for Optimizing High-Order Multiple-Quantum Transition Intensities}, journal = {Journal of Magnetic Resonance}, volume = {46}, year = {1982}, note = {J Magn ResonNc063Times Cited:24Cited References Count:11}, pages = {529-534}, isbn = {1090-7807}, doi = {Doi 10.1016/0022-2364(82)90104-4}, url = {://WOS:A1982NC06300015}, author = {Weitekamp, D. P. and Garbow, J. R. and Pines, A.} } @article {646, title = {Simple Pulse Sequences for Selective Multiple-Quantum Excitation}, journal = {Chemical Physics Letters}, volume = {88}, year = {1982}, note = {Chem Phys LettNs759Times Cited:15Cited References Count:12}, pages = {441-443}, isbn = {0009-2614}, doi = {Doi 10.1016/0009-2614(82)83042-X}, url = {://WOS:A1982NS75900018}, author = {Warren, W. S. and Pines, A.} } @article {647, title = {Time-Resolved Optical Nuclear-Polarization by Rapid Field Switching}, journal = {Chemical Physics Letters}, volume = {93}, year = {1982}, note = {Chem Phys LettPv837Times Cited:4Cited References Count:15}, pages = {392-395}, isbn = {0009-2614}, doi = {Doi 10.1016/0009-2614(82)83716-0}, url = {://WOS:A1982PV83700018}, author = {Tycko, R. and Pines, A. and Stehlik, D.} } @article {653, title = {Analogy of Multiple-Quantum Nmr to Isotopic Spin Labeling}, journal = {Journal of the American Chemical Society}, volume = {103}, year = {1981}, note = {J Am Chem SocLk271Times Cited:43Cited References Count:40}, pages = {1613-1617}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja00397a001}, url = {://WOS:A1981LK27100001}, author = {Warren, W. S. and Pines, A.} } @article {651, title = {C-13 Chemical-Shifts in Solid Metal Sandwich Compounds}, journal = {Journal of the American Chemical Society}, volume = {103}, year = {1981}, note = {J Am Chem SocKy444Times Cited:40Cited References Count:8}, pages = {34-36}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja00391a007}, url = {://WOS:A1981KY44400007}, author = {Wemmer, D. E. and Pines, A.} } @article {650, title = {C-13 Nmr-Studies of Coal and Coal Extracts}, journal = {Philosophical Transactions of the Royal Society a-Mathematical Physical and Engineering Sciences}, volume = {300}, year = {1981}, note = {Philos T R Soc ALj670Times Cited:50Cited References Count:25}, pages = {15-41}, isbn = {1364-503X}, doi = {Doi 10.1098/Rsta.1981.0045}, url = {://WOS:A1981LJ67000002}, author = {Wemmer, D. E. and Pines, A. and Whitehurst, D. D.} } @article {655, title = {Dipolar Relaxation by Rotation in Spin Space}, journal = {Journal of Magnetic Resonance}, volume = {45}, year = {1981}, note = {J Magn ResonMk798Times Cited:7Cited References Count:28}, pages = {94-101}, isbn = {1090-7807}, doi = {Doi 10.1016/0022-2364(81)90103-7}, url = {://WOS:A1981MK79800009}, author = {Emid, S. and Smidt, J. and Pines, A.} } @article {654, title = {Experiments on Selective Excitation of Multiple-Quantum Transitions in Nmr-Spectroscopy}, journal = {Journal of Chemical Physics}, volume = {74}, year = {1981}, note = {J Chem PhysLg574Times Cited:57Cited References Count:23}, pages = {2808-2818}, isbn = {0021-9606}, doi = {Doi 10.1063/1.441452}, url = {://WOS:A1981LG57400021}, author = {Warren, W. S. and Pines, A.} } @article {652, title = {High-Resolution Nmr-Spectra in Inhomogeneous Magnetic-Fields - Application of Total Spin Coherence Transfer Echoes}, journal = {Journal of the American Chemical Society}, volume = {103}, year = {1981}, note = {J Am Chem SocLt874Times Cited:64Cited References Count:10}, pages = {3578-3579}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja00402a057}, url = {://WOS:A1981LT87400057}, author = {Weitekamp, D. P. and Garbow, J. R. and Murdoch, J. B. and Pines, A.} } @article {649, title = {Nmr-Study of Molecular-Reorientation under Fivefold Symmetry - Solid Permethylferrocene}, journal = {Journal of the American Chemical Society}, volume = {103}, year = {1981}, note = {J Am Chem SocKy444Times Cited:68Cited References Count:21}, pages = {28-33}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja00391a006}, url = {://WOS:A1981KY44400006}, author = {Wemmer, D. E. and Ruben, D. J. and Pines, A.} } @article {656, title = {Selectivity in Multiple-Quantum Spectroscopy}, journal = {Philosophical Transactions of the Royal Society a-Mathematical Physical and Engineering Sciences}, volume = {299}, year = {1981}, note = {Philos T R Soc ALj669Times Cited:19Cited References Count:17}, pages = {585-592}, isbn = {1364-503X}, doi = {Doi 10.1098/Rsta.1981.0036}, url = {://WOS:A1981LJ66900008}, author = {Drobny, G. and Pines, A. and Sinton, S. and Warren, W. S. and Weitekamp, D. P.} } @article {660, title = {Anisotropic Spin-Lattice Relaxation of Deuterated Hexamethylbenzene}, journal = {Journal of Magnetic Resonance}, volume = {41}, year = {1980}, note = {J Magn ResonKx294Times Cited:25Cited References Count:7}, pages = {389-394}, isbn = {1090-7807}, doi = {Doi 10.1016/0022-2364(80)90294-2}, url = {://WOS:A1980KX29400004}, author = {Tang, J. and Sterna, L. and Pines, A.} } @article {669, title = {Deuterium Double-Quantum Nmr with Magic Angle Spinning}, journal = {Chemical Physics Letters}, volume = {74}, year = {1980}, note = {Chem Phys LettKh902Times Cited:35Cited References Count:13}, pages = {376-378}, isbn = {0009-2614}, doi = {Doi 10.1016/0009-2614(80)85182-7}, url = {://WOS:A1980KH90200041}, author = {Eckman, R. and Muller, L. and Pines, A.} } @article {670, title = {Deuterium Nmr in Solids with a Cylindrical Magic Angle Sample Spinner}, journal = {Journal of Magnetic Resonance}, volume = {41}, year = {1980}, note = {J Magn ResonKx294Times Cited:41Cited References Count:10}, pages = {440-446}, isbn = {1090-7807}, doi = {Doi 10.1016/0022-2364(80)90301-7}, url = {://WOS:A1980KX29400011}, author = {Eckman, R. and Alla, M. and Pines, A.} } @article {659, title = {Double-Quantum Cross-Polarization Nmr in Solids}, journal = {Physical Review A}, volume = {22}, year = {1980}, note = {Phys Rev AKb812Times Cited:53Cited References Count:27}, pages = {638-661}, isbn = {1050-2947}, doi = {Doi 10.1103/Physreva.22.638}, url = {://WOS:A1980KB81200041}, author = {Vega, S. and Shattuck, T. W. and Pines, A.} } @article {658, title = {High-Order Selective Sequences in Multiple-Quantum Nmr}, journal = {Journal of Magnetic Resonance}, volume = {40}, year = {1980}, note = {J Magn ResonKh908Times Cited:21Cited References Count:3}, pages = {581-583}, isbn = {1090-7807}, doi = {Doi 10.1016/0022-2364(80)90015-3}, url = {://WOS:A1980KH90800015}, author = {Warren, W. S. and Weitekamp, D. P. and Pines, A.} } @article {662, title = {Multiple Quantum Nmr and Relaxation of an Oriented Ch3 Group}, journal = {Journal of Chemical Physics}, volume = {72}, year = {1980}, note = {J Chem PhysJm229Times Cited:41Cited References Count:26}, pages = {3290-3297}, isbn = {0021-9606}, doi = {Doi 10.1063/1.439565}, url = {://WOS:A1980JM22900051}, author = {Tang, J. and Pines, A.} } @article {663, title = {Multiple Quantum Nmr-Study of Correlation of 2 Methyl-Groups}, journal = {Journal of Chemical Physics}, volume = {73}, year = {1980}, note = {J Chem PhysKh292Times Cited:18Cited References Count:14}, pages = {2512-2513}, isbn = {0021-9606}, doi = {Doi 10.1063/1.440366}, url = {://WOS:A1980KH29200064}, author = {Tang, J. and Pines, A.} } @article {666, title = {Proton-Enhanced Deuterium Nmr in Rotating Solids}, journal = {Chemical Physics Letters}, volume = {76}, year = {1980}, note = {Chem Phys LettKt859Times Cited:10Cited References Count:22}, pages = {149-154}, isbn = {0009-2614}, doi = {Doi 10.1016/0009-2614(80)80625-7}, url = {://WOS:A1980KT85900034}, author = {Muller, L. and Eckman, R. and Pines, A.} } @article {667, title = {Selective Double-Quantum Nmr in Solids}, journal = {Chemical Physics Letters}, volume = {73}, year = {1980}, note = {Chem Phys LettKe433Times Cited:7Cited References Count:24}, pages = {496-499}, isbn = {0009-2614}, doi = {Doi 10.1016/0009-2614(80)80703-2}, url = {://WOS:A1980KE43300021}, author = {Emid, S. and Smidt, J. and Pines, A.} } @article {668, title = {On the short time behavior of the dipolar signal in relaxation measurements by the pulse method}, journal = {Physica}, year = {1980}, pages = {215-218}, author = {Emid, S. and Konijnendijk, J. and Schmidt, J. and Pines, A.} } @article {671, title = {Spin Diffusion and Spin-Lattice Relaxation of Deuterium in Rotating Solids}, journal = {Chemical Physics Letters}, volume = {71}, year = {1980}, note = {Chem Phys LettJq737Times Cited:39Cited References Count:7}, pages = {148-151}, isbn = {0009-2614}, doi = {Doi 10.1016/0009-2614(80)85309-7}, url = {://WOS:A1980JQ73700031}, author = {Alla, M. and Eckman, R. and Pines, A.} } @article {661, title = {Spin-Lattice Relaxation of Reorienting or Tunneling Deuterated Methyl-Groups}, journal = {Journal of Chemical Physics}, volume = {73}, year = {1980}, note = {J Chem PhysKb127Times Cited:10Cited References Count:18}, pages = {172-175}, isbn = {0021-9606}, doi = {Doi 10.1063/1.439903}, url = {://WOS:A1980KB12700025}, author = {Tang, J. and Pines, A. and Emid, S.} } @article {665, title = {Study of Liquid-Crystal Conformation by Multiple Quantum Nmr - Normal-Pentyl Cyanobiphenyl}, journal = {Chemical Physics Letters}, volume = {76}, year = {1980}, note = {Chem Phys LettKx693Times Cited:104Cited References Count:19}, pages = {263-267}, isbn = {0009-2614}, doi = {Doi 10.1016/0009-2614(80)87017-5}, url = {://WOS:A1980KX69300017}, author = {Sinton, S. and Pines, A.} } @article {657, title = {Theory of Selective Excitation of Multiple-Quantum Transitions}, journal = {Journal of Chemical Physics}, volume = {73}, year = {1980}, note = {J Chem PhysKh292Times Cited:159Cited References Count:26}, pages = {2084-2099}, isbn = {0021-9606}, doi = {Doi 10.1063/1.440403}, url = {://WOS:A1980KH29200011}, author = {Warren, W. S. and Weitekamp, D. P. and Pines, A.} } @article {664, title = {Viscosity and Temperature-Dependence of the Magnetic Isotope Effect}, journal = {Journal of Chemical Physics}, volume = {73}, year = {1980}, note = {J Chem PhysKx295Times Cited:53Cited References Count:35}, pages = {5493-5499}, isbn = {0021-9606}, doi = {Doi 10.1063/1.440068}, url = {://WOS:A1980KX29500010}, author = {Sterna, L. and Ronis, D. and Wolfe, S. and Pines, A.} } @article {675, title = {Experimental Results on Deuterium Nmr in the Solid-State by Magic Angle Sample Spinning}, journal = {Chemical Physics}, volume = {42}, year = {1979}, note = {Chem PhysHl541Times Cited:50Cited References Count:15}, pages = {423-428}, isbn = {0301-0104}, doi = {Doi 10.1016/0301-0104(79)80092-0}, url = {://WOS:A1979HL54100022}, author = {Ackerman, J. L. and Eckman, R. and Pines, A.} } @article {674, title = {Multiple Quantum Coherence in Dipolar Relaxation Measurements}, journal = {Physica B \& C}, volume = {96}, year = {1979}, note = {Physica B \& CHb239Times Cited:26Cited References Count:9}, pages = {333-336}, isbn = {0378-4371}, doi = {Doi 10.1016/0378-4363(79)90018-4}, url = {://WOS:A1979HB23900006}, author = {Emid, S. and Bax, A. and Konijnendijk, J. and Smidt, J. and Pines, A.} } @article {673, title = {Quantitative Aspects of Deuteron (Spin 1) Spin Decoupling in Solid-State Nmr}, journal = {Physical Review B}, volume = {19}, year = {1979}, note = {Phys Rev BGn686Times Cited:13Cited References Count:14}, pages = {238-246}, isbn = {0163-1829}, doi = {Doi 10.1103/Physrevb.19.238}, url = {://WOS:A1979GN68600029}, author = {Suwelack, D. and Mehring, M. and Pines, A.} } @article {672, title = {Selective Excitation of Multiple-Quantum Coherence in Nuclear Magnetic-Resonance}, journal = {Physical Review Letters}, volume = {43}, year = {1979}, note = {Phys Rev LettHw700Times Cited:85Cited References Count:14}, pages = {1791-1794}, isbn = {0031-9007}, doi = {Doi 10.1103/Physrevlett.43.1791}, url = {://WOS:A1979HW70000008}, author = {Warren, W. S. and Sinton, S. and Weitekamp, D. P. and Pines, A.} } @article {676, title = {5-Quantum and 6-Quantum Nmr-Spectra of Oriented Benzene}, journal = {Bulletin of the American Physical Society}, volume = {23}, year = {1978}, note = {B Am Phys SocEg455Times Cited:27Cited References Count:3}, pages = {21-21}, isbn = {0003-0503}, url = {://WOS:A1978EG45500071}, author = {Pines, A. and Wemmer, D. and Tang, J. and Sinton, S.} } @article {679, title = {Fourier transform multiple quantum nuclear magnetic resonance}, journal = {Faraday Symposia of the Chemical Society}, volume = {13}, year = {1978}, pages = {49-55}, abstract = {

The excitation and detection of multiple quantum transitions in systems of coupled spins offers, among other advantages, an increase in resolution over single quantum n.m.r. since the number of lines decreases as the order of the transition increases. This paper reviews the motivation for detecting multiple quantum transitions by a Fourier transform experiment and describes an experimental approach to high resolution multiple quantum spectra in dipolar systems along with results on some protonated liquid crystal systems. A simple operator formalism for the essential features of the time development is presented and some applications in progress are discussed.

}, isbn = {0301-5696}, url = {http://dx.doi.org/10.1039/FS9781300049}, author = {Drobny, Gary and Pines, Alexander and Sinton, Steven and Weitekamp, Daniel P. and Wemmer, David} } @article {677, title = {Nmr Double-Quantum Spin Decoupling in Solids}, journal = {Physical Review B}, volume = {18}, year = {1978}, note = {Phys Rev BFl373Times Cited:35Cited References Count:28}, pages = {112-125}, isbn = {1098-0121}, doi = {Doi 10.1103/Physrevb.18.112}, url = {://WOS:A1978FL37300014}, author = {Pines, A. and Vega, S. and Mehring, M.} } @article {678, title = {Review of NMR, Basic Principles and Progress volume II by Springer Verlag}, journal = {Journal of Magnetic Resonance}, year = {1978}, pages = {356}, author = {Pines, A.} } @inbook {682, title = {Double quantum NMR in solids}, booktitle = {Magnetic Resonance in Condensed Matter: Recent developments}, year = {1977}, pages = {127-129}, publisher = {University of Ljubljana Press}, organization = {University of Ljubljana Press}, author = {Pines, A. and Vega, S. and Ruben, D.J. and Shattuck, T.W. and Wemmer, D.}, editor = {Lahajanr, R. Blinc and G.} } @article {681, title = {Operator Formalism for Double Quantum Nmr}, journal = {Journal of Chemical Physics}, volume = {66}, year = {1977}, note = {J Chem PhysDl332Times Cited:348Cited References Count:20}, pages = {5624-5644}, isbn = {0021-9606}, doi = {Doi 10.1063/1.433884}, url = {://WOS:A1977DL33200046}, author = {Vega, S. and Pines, A.} } @inbook {680, title = {Theory of double-quantum coherence and high resolution deuterium NMR in solids}, booktitle = {Magnetic resonance and related phenomena}, year = {1977}, pages = {395-400}, publisher = {Beltz-Offsetdruck}, organization = {Beltz-Offsetdruck}, address = {Heidelburg}, author = {Vega, S. and Pines, A.}, editor = {Hausser, K.} } @proceedings {683, title = {Application of novel NMR techniques to coal structure}, journal = {Coal Chemistry Workshop}, year = {1976}, pages = {229}, address = {Stanford}, author = {Wemmer, D. and Whitehurst, D. and Pines, A.} } @article {685, title = {Dynamics of Spin Decoupling in Carbon-13-Proton Nmr}, journal = {Chemical Physics Letters}, volume = {43}, year = {1976}, note = {Chem Phys LettCk656Times Cited:35Cited References Count:19}, pages = {382-386}, isbn = {0009-2614}, doi = {Doi 10.1016/0009-2614(76)85325-0}, url = {://WOS:A1976CK65600042}, author = {Sinning, G. and Mehring, M. and Pines, A.} } @article {684, title = {Fourier-Transform Double-Quantum Nmr in Solids}, journal = {Physical Review Letters}, volume = {37}, year = {1976}, note = {Phys Rev LettBv563Times Cited:139Cited References Count:12}, pages = {43-46}, isbn = {0031-9007}, doi = {Doi 10.1103/Physrevlett.37.43}, url = {://WOS:A1976BV56300013}, author = {Vega, S. and Shattuck, T. W. and Pines, A.} } @article {686, title = {New Approach to High-Resolution Proton Nmr in Solids - Deuterium Spin Decoupling by Multiple-Quantum Transitions}, journal = {Physical Review Letters}, volume = {36}, year = {1976}, note = {Phys Rev LettBb171Times Cited:105Cited References Count:12}, pages = {110-113}, isbn = {0031-9007}, doi = {Doi 10.1103/Physrevlett.36.110}, url = {://WOS:A1976BB17100014}, author = {Pines, A. and Ruben, D. J. and Vega, S. and Mehring, M.} } @article {687, title = {Nmr Line Broadening in Solids by Slowing down of Spin Fluctuations}, journal = {Zeitschrift Fur Physik B-Condensed Matter}, volume = {24}, year = {1976}, note = {Z Phys B Con MatBs166Times Cited:23Cited References Count:13}, pages = {73-76}, isbn = {0722-3277}, doi = {Doi 10.1007/Bf01312875}, url = {://WOS:A1976BS16600009}, author = {Mehring, M. and Sinning, G. and Pines, A.} } @article {689, title = {C-13 Chemical Shielding in Oxalic-Acid, Oxalic-Acid Dihydrate, and Diammonium Oxalate}, journal = {Journal of Chemical Physics}, volume = {63}, year = {1975}, note = {J Chem PhysAk998Times Cited:49Cited References Count:20}, pages = {1267-1271}, isbn = {0021-9606}, doi = {Doi 10.1063/1.431418}, url = {://WOS:A1975AK99800034}, author = {Griffin, R. G. and Pines, A. and Pausak, S. and Waugh, J. S.} } @article {691, title = {C-13 Chemical Shielding Tensors in Ammonium Hydrogen Malonate}, journal = {Journal of Chemical Physics}, volume = {62}, year = {1975}, note = {J Chem PhysAf060Times Cited:23Cited References Count:14}, pages = {4923-4926}, isbn = {0021-9606}, doi = {Doi 10.1063/1.430406}, url = {://WOS:A1975AF06000046}, author = {Chang, J. J. and Griffin, R. G. and Pines, A.} } @article {688, title = {Observation of C-13-N-14 Dipolar Couplings in Single-Crystals of Glycine}, journal = {Journal of Chemical Physics}, volume = {63}, year = {1975}, note = {J Chem PhysAt263Times Cited:24Cited References Count:10}, pages = {3676-3677}, isbn = {0021-9606}, doi = {Doi 10.1063/1.431768}, url = {://WOS:A1975AT26300072}, author = {Griffin, R. G. and Pines, A. and Waugh, J. S.} } @article {690, title = {Qualitative Analysis of Chemisorbed Molecular Species Via C-13 Nmr}, journal = {Surface Science}, volume = {47}, year = {1975}, note = {Surf SciV7219Times Cited:36Cited References Count:22}, pages = {661-665}, isbn = {0039-6028}, doi = {Doi 10.1016/0039-6028(75)90211-3}, url = {://WOS:A1975V721900023}, author = {Chang, J. J. and Pines, A. and Fripiat, J. J. and Resing, H. A.} } @article {703, title = {C-13 and N-15 chemical shielding anisotropy in acetonitrile}, journal = {Chemical Physics Letters}, year = {1974}, pages = {78}, author = {Kaplan, S. and Pines, A. and Griffin, R.G. and Waugh, J.S.} } @article {697, title = {C-13 Nuclear Magnetic-Resonance in Solid Ammonium-Tartrate}, journal = {Journal of Chemical Physics}, volume = {61}, year = {1974}, note = {J Chem PhysT7994Times Cited:76Cited References Count:35}, pages = {1021-1030}, isbn = {0021-9606}, doi = {Doi 10.1063/1.1681970}, url = {://WOS:A1974T799400040}, author = {Pines, A. and Chang, J. J. and Griffin, R. G.} } @article {693, title = {C-13 Proton Nmr Cross-Polarization Times in Solid Adamantane}, journal = {Journal of Chemical Physics}, volume = {61}, year = {1974}, note = {J Chem PhysT7994Times Cited:44Cited References Count:16}, pages = {1255-1256}, isbn = {0021-9606}, doi = {Doi 10.1063/1.1682009}, url = {://WOS:A1974T799400079}, author = {Pines, A. and Shattuck, T. W.} } @article {704, title = {Chemical Shielding Anisotropy of C-13 and N-15 in Acetonitrile}, journal = {Chemical Physics Letters}, volume = {25}, year = {1974}, note = {Chem Phys LettS5222Times Cited:46Cited References Count:8}, pages = {78-79}, isbn = {0009-2614}, doi = {Doi 10.1016/0009-2614(74)80336-2}, url = {://WOS:A1974S522200017}, author = {Kaplan, S. and Pines, A. and Griffin, R. G. and Waugh, J. S.} } @article {705, title = {Chemical Shielding Tensor of C-13 in a Carboxyl Group}, journal = {Journal of Chemical Physics}, volume = {60}, year = {1974}, note = {J Chem PhysS6878Times Cited:22Cited References Count:10}, pages = {2561-2562}, isbn = {0021-9606}, doi = {Doi 10.1063/1.1681401}, url = {://WOS:A1974S687800054}, author = {Chang, J. J. and Griffin, R. G. and Pines, A.} } @article {695, title = {Chemical Shielding Tensors of C-13 in Oxalates}, journal = {Bulletin of the American Physical Society}, volume = {19}, year = {1974}, note = {B Am Phys SocS5575Times Cited:0Cited References Count:1}, pages = {486-487}, isbn = {0003-0503}, url = {://WOS:A1974S557500422}, author = {Pines, A. and Griffin, R. G. and Waugh, J. S.} } @article {700, title = {Chemical Shielding Tensors of C-13 in Solid Dimethyl Oxalate}, journal = {Journal of Chemical Physics}, volume = {60}, year = {1974}, note = {J Chem PhysT5858Times Cited:29Cited References Count:9}, pages = {5130-5131}, isbn = {0021-9606}, doi = {Doi 10.1063/1.1681041}, url = {://WOS:A1974T585800081}, author = {Pines, A. and Abramson, E.} } @article {692, title = {Dipolar Spin Temperature in a Periodically Perturbed Nuclear Spin System}, journal = {Physics Letters A}, volume = {A 47}, year = {1974}, note = {Phys Lett AS7970Times Cited:11Cited References Count:5}, pages = {337-338}, isbn = {0375-9601}, doi = {Doi 10.1016/0375-9601(74)90192-3}, url = {://WOS:A1974S797000033}, author = {Pines, A. and Waugh, J. S.} } @article {698, title = {Effect of Phase-Transitions on C-13 Nuclear Magnetic-Resonance Spectra in Para-Azoxydianisole, a Nematic Liquid-Crystal}, journal = {Journal of the American Chemical Society}, volume = {96}, year = {1974}, note = {J Am Chem SocT8383Times Cited:28Cited References Count:14}, pages = {5590-5591}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja00824a057}, url = {://WOS:A1974T838300057}, author = {Pines, A. and Chang, J. J.} } @article {696, title = {High-Resolution C-13 Nmr in Solid Ammonium-Tartrate}, journal = {Bulletin of the American Physical Society}, volume = {19}, year = {1974}, note = {B Am Phys SocS1647Times Cited:0Cited References Count:0}, pages = {349-349}, isbn = {0003-0503}, url = {://WOS:A1974S164701005}, author = {Pines, A. and Chang, J. J. and Griffin, R. G.} } @article {694, title = {Molecular Ordering and Even-Odd Effect in a Homologous Series of Nematic Liquid-Crystals}, journal = {Physical Review Letters}, volume = {33}, year = {1974}, note = {Phys Rev LettU3736Times Cited:72Cited References Count:26}, pages = {1002-1005}, isbn = {0031-9007}, doi = {Doi 10.1103/Physrevlett.33.1002}, url = {://WOS:A1974U373600004}, author = {Pines, A. and Ruben, D. J. and Allison, S.} } @article {701, title = {Review of Advances in Magnetic Resonance}, journal = {Journal of the American Chemical Society}, volume = {6}, year = {1974}, pages = {6538}, author = {Pines, A.} } @article {702, title = {Simple Data Acquisition-System for Proton-Enhanced Nuclear Induction Spectroscopy}, journal = {Journal of Magnetic Resonance}, volume = {14}, year = {1974}, note = {J Magn ResonT4998Times Cited:2Cited References Count:7}, pages = {270-273}, isbn = {1090-7807}, doi = {Doi 10.1016/0022-2364(74)90283-2}, url = {://WOS:A1974T499800003}, author = {Merrick, T. and Smiriga, S. and Pines, A.} } @article {699, title = {Study of Isotropic-Nematic-Solid Transitions in a Liquid-Crystal by Carbon-13-Proton Double-Resonance}, journal = {Physical Review A}, volume = {10}, year = {1974}, note = {Phys Rev AU0398Times Cited:73Cited References Count:18}, pages = {946-949}, isbn = {1050-2947}, doi = {Doi 10.1103/Physreva.10.946}, url = {://WOS:A1974U039800024}, author = {Pines, A. and Chang, J. J.} } @article {710, title = {C-13 Chemical Shielding Tensors in Single-Crystal Durene}, journal = {Journal of Chemical Physics}, volume = {59}, year = {1973}, note = {J Chem PhysQ3293Times Cited:124Cited References Count:22}, pages = {591-595}, isbn = {0021-9606}, doi = {Doi 10.1063/1.1680062}, url = {://WOS:A1973Q329300002}, author = {Pausak, S. and Pines, A. and Waugh, J. S.} } @article {711, title = {Electrochemical Synthesis of Cis-3,4-Dicarbomethoxycyclobutene}, journal = {Israel Journal of Chemistry}, volume = {11}, year = {1973}, note = {Israel J ChemP7708Times Cited:5Cited References Count:13}, pages = {75-77}, isbn = {0021-2148}, url = {://WOS:A1973P770800010}, author = {Leftin, J. H. and Redpath, D. and Pines, A. and Gilav, E.} } @article {706, title = {Enhanced Inhomogeneous Nuclear Spin Echoes for Dilute Spins in Solids}, journal = {Chemical Physics Letters}, volume = {23}, year = {1973}, note = {Chem Phys LettS0678Times Cited:16Cited References Count:14}, pages = {614-616}, isbn = {0009-2614}, doi = {Doi 10.1016/0009-2614(73)89042-6}, url = {://WOS:A1973S067800042}, author = {Pines, A. and Shattuck, T. W.} } @article {712, title = {Optically Detected Electron-Spin Echoes and Free Precession in Molecular Excited-States}, journal = {Physical Review Letters}, volume = {30}, year = {1973}, note = {Phys Rev LettO5544Times Cited:56Cited References Count:25}, pages = {158-161}, isbn = {0031-9007}, doi = {Doi 10.1103/Physrevlett.30.158}, url = {://WOS:A1973O554400002}, author = {Breiland, W. G. and Harris, C. B. and Pines, A.} } @article {707, title = {Proton-Enhanced Nmr of Dilute Spins in Solids}, journal = {Journal of Chemical Physics}, volume = {59}, year = {1973}, note = {J Chem PhysQ3293Times Cited:2144Cited References Count:119}, pages = {569-590}, isbn = {0021-9606}, doi = {Doi 10.1063/1.1680061}, url = {://WOS:A1973Q329300001}, author = {Pines, A. and Gibby, M. G. and Waugh, J. S.} } @article {708, title = {Pulsed Spin Decoupling in Nuclear Magnetic-Resonance}, journal = {Journal of the American Chemical Society}, volume = {95}, year = {1973}, note = {J Am Chem SocQ0006Times Cited:7Cited References Count:5}, pages = {4437-4438}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja00794a059}, url = {://WOS:A1973Q000600060}, author = {Pines, A. and Ellett, J. D.} } @proceedings {709, title = {Sensitivity in high resolution nuclear magnetic double resonance, proceedings of the first specialized colloque ampere}, journal = {The First Specialized Colloque Ampere}, year = {1973}, pages = {165-170}, address = {Krakow, Poland}, author = {Pines, A.} } @article {720, title = {Anisotropic Nuclear Spin Relaxation of C-13 in Solid Benzene}, journal = {Chemical Physics Letters}, volume = {16}, year = {1972}, note = {Chem Phys LettN8559Times Cited:53Cited References Count:17}, pages = {296-\&}, isbn = {0009-2614}, doi = {Doi 10.1016/0009-2614(72)80276-8}, url = {://WOS:A1972N855900018}, author = {Gibby, M. G. and Waugh, J. S. and Pines, A.} } @article {722, title = {High-Resolution Nmr of N-15 in Solids}, journal = {Chemical Physics Letters}, volume = {17}, year = {1972}, note = {Chem Phys LettO4215Times Cited:47Cited References Count:17}, pages = {80-84}, isbn = {0009-2614}, doi = {Doi 10.1016/0009-2614(72)80330-0}, url = {://WOS:A1972O421500021}, author = {Gibby, M. G. and Griffin, R. G. and Pines, A. and Waugh, J. S.} } @article {718, title = {Homogeneous and Inhomogeneous Nuclear Spin Echoes in Solids}, journal = {Journal of Magnetic Resonance}, volume = {6}, year = {1972}, note = {J Magn ResonM2264Times Cited:33Cited References Count:32}, pages = {457-\&}, isbn = {1090-7807}, doi = {Doi 10.1016/0022-2364(72)90154-0}, url = {://WOS:A1972M226400001}, author = {Pines, A. and Rhim, W. and Waugh, J. S.} } @article {719, title = {P-31 Chemical Shielding Anisotropy in Solids - Single-Crystal and Powder Studies at 99.4 Mhz}, journal = {Journal of Chemical Physics}, volume = {56}, year = {1972}, note = {J Chem PhysL3043Times Cited:33Cited References Count:21}, pages = {991-\&}, isbn = {0021-9606}, doi = {Doi 10.1063/1.1677259}, url = {://WOS:A1972L304300043}, author = {Gibby, M. G. and Waugh, J. S. and Pines, A. and Rhim, W. K.} } @proceedings {714, title = {Proton-enhance NMR of dilute spins in solids, proceedings of the congress ampere}, journal = {The Congress Ampere}, year = {1972}, pages = {11-17}, publisher = {North Holland Publishers}, address = {Turku, Finland}, author = {Waugh, J.S. and Gibby, M.G. and Kaplan, S. and Pines, A.} } @article {716, title = {Proton-Enhanced Nuclear Induction Spectroscopy C-13 Chemical Shielding Anisotropy in Some Organic Solids}, journal = {Chemical Physics Letters}, volume = {15}, year = {1972}, note = {Chem Phys LettN5315Times Cited:290Cited References Count:10}, pages = {373-\&}, isbn = {0009-2614}, doi = {Doi 10.1016/0009-2614(72)80191-X}, url = {://WOS:A1972N531500014}, author = {Pines, A. and Waugh, J. S. and Gibby, M. G.} } @article {715, title = {Proton-Enhanced Nuclear Induction Spectroscopy - Method for High-Resolution Nmr of Dilute Spins in Solids}, journal = {Journal of Chemical Physics}, volume = {56}, year = {1972}, note = {J Chem PhysL5803Times Cited:520Cited References Count:10}, pages = {1776-\&}, isbn = {0021-9606}, doi = {Doi 10.1063/1.1677439}, url = {://WOS:A1972L580300054}, author = {Pines, A. and Waugh, J. S. and Gibby, M. G.} } @article {721, title = {Proton-Enhanced Nuclear Induction Spectroscopy - Silicon-29 Chemical Shielding Anisotropy in Some Organosilicon Compounds}, journal = {Journal of the American Chemical Society}, volume = {94}, year = {1972}, note = {J Am Chem SocN2839Times Cited:31Cited References Count:5}, pages = {6231-\&}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja00772a071}, url = {://WOS:A1972N283900071}, author = {Gibby, M. G. and Pines, A. and Waugh, J. S.} } @article {717, title = {Quantitative Aspects of Coherent Averaging - Simple Treatment of Resonance Offset Processes in Multiple-Pulse Nmr}, journal = {Journal of Magnetic Resonance}, volume = {8}, year = {1972}, note = {J Magn ResonO1700Times Cited:34Cited References Count:38}, pages = {354-\&}, isbn = {1090-7807}, doi = {Doi 10.1016/0022-2364(72)90053-4}, url = {://WOS:A1972O170000009}, author = {Pines, A. and Waugh, J. S.} } @article {713, title = {Spin Echoes and Loschmidt{\textquoteright}s paradox}, journal = {Journal Pure Applied Chemistry}, volume = {32}, year = {1972}, pages = {317-324}, author = {Waugh, J.S. and Rhim, W.-K. and Pines, A.} } @article {724, title = {C-13 Chemical Shielding Anisotropy in Solids - Cs2 and Caco3}, journal = {Journal of Chemical Physics}, volume = {54}, year = {1971}, note = {J Chem PhysJ6303Times Cited:30Cited References Count:17}, pages = {5438-\&}, isbn = {0021-9606}, doi = {Doi 10.1063/1.1674855}, url = {://WOS:A1971J630300070}, author = {Pines, A. and Rhim, W. K. and Waugh, J. S.} } @article {726, title = {High Resolution Nmr of Dilute Spins in Solids}, journal = {Bulletin of the American Physical Society}, volume = {16}, year = {1971}, note = {B Am Phys SocL0382Times Cited:0Cited References Count:3}, pages = {1408-\&}, isbn = {0003-0503}, url = {://WOS:A1971L038200080}, author = {Pines, A. and Gibby, M. G. and Waugh, J. S.} } @article {725, title = {Nuclear Magnetic Resonance Study of Dipolar Contribution to Ground State in a Series of Fulvenes}, journal = {Journal of the Chemical Society B-Physical Organic}, year = {1971}, note = {J Chem Soc BI6991Times Cited:12Cited References Count:20}, pages = {385-\&}, doi = {Doi 10.1039/J29710000385}, url = {://WOS:A1971I699100040}, author = {Pines, A. and Rabinovi.M} } @article {728, title = {Spectrometers for multiple pulse NMR}, journal = {Advances in Magnetic Resonance}, volume = {5}, year = {1971}, pages = {117-175}, author = {Ellett, J.D., Jr. and Gibby, M.G. and Haeberlen, U. and Huber, L.M. and Mehring, M. and Pines, A. and Waugh, J.S.} } @article {727, title = {Spin-Decoupling in Resolution of Chemical Shifts in Solids by Pulsed Nmr}, journal = {Journal of Chemical Physics}, volume = {54}, year = {1971}, note = {J Chem PhysJ1849Times Cited:49Cited References Count:9}, pages = {3239-\&}, isbn = {0021-9606}, doi = {Doi 10.1063/1.1675324}, url = {://WOS:A1971J184900070}, author = {Mehring, M. and Pines, A. and Rhim, W. K. and Waugh, J. S.} } @article {723, title = {Time-Reversal Experiments in Dipolar-Coupled Spin Systems}, journal = {Physical Review B}, volume = {3}, year = {1971}, note = {Phys Rev BI5979Times Cited:281Cited References Count:36}, pages = {684-\&}, doi = {Doi 10.1103/Physrevb.3.684}, url = {://WOS:A1971I597900016}, author = {Rhim, W. K. and Pines, A. and Waugh, J. S.} } @article {729, title = {Violation of Spin-Temperature Hypothesis}, journal = {Physical Review Letters}, volume = {25}, year = {1970}, note = {Phys Rev LettG8549Times Cited:140Cited References Count:17}, pages = {218-\&}, isbn = {0031-9007}, doi = {Doi 10.1103/Physrevlett.25.218}, url = {://WOS:A1970G854900007}, author = {Rhim, W. K. and Pines, A. and Waugh, J. S.} } @booklet {734, title = {Hindered Internal Rotation and Dimerization of N,N-Dimethylformamide in Carbon Tetrachloride}, journal = {Journal of the American Chemical Society}, volume = {91}, year = {1969}, note = {J Am Chem SocC9912Times Cited:170Cited References Count:39}, pages = {1585-\&}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja01035a001}, url = {://WOS:A1969C991200001}, author = {Rabinovi, M. and Pines, A.} } @article {733, title = {3 Geometrical Isomers of a 2,4-Disubstituted Bicyclobutane}, journal = {Chemical Communications}, year = {1968}, note = {Chem CommunA9390Times Cited:4Cited References Count:5}, pages = {396-\&}, isbn = {1359-7345}, doi = {Doi 10.1039/C19680000396}, url = {://WOS:A1968A939000036}, author = {Leftin, J. H. and Gilav, E. and Pines, A.} } @article {735, title = {Association of Dimethylformamide Molecules in Carbon Tetrachloride Solution}, journal = {Journal of the Chemical Society B-Physical Organic}, year = {1968}, note = {J Chem Soc BC0167Times Cited:47Cited References Count:14}, pages = {1110-\&}, doi = {Doi 10.1039/J29680001110}, url = {://WOS:A1968C016700007}, author = {Rabinovi, M. and Pines, A.} } @article {736, title = {A Nuclear Magnetic Resonance Total Line-Shape Treatment of Internal Rotation in Dimethylformamide}, journal = {Tetrahedron Letters}, year = {1968}, note = {Tetrahedron LettB1658Times Cited:26Cited References Count:15}, pages = {3529-\&}, isbn = {0040-4039}, url = {://WOS:A1968B165800021}, author = {Pines, A. and Rabinovi, M.} } @article {1925, title = {Non-disruptive dissolution of hp-129Xe in viscou aqueous and organic liquid crystalline environments}, author = {Ashley E. Truxal and Clancy C. Slack and Muller D. Gomes and Christophoros C. Vassiliou and David E. Wemmer and Alexander Pines} }