@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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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.} } @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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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.} } @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 {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.} } @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.} } @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 {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 {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 {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 {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 {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 {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 {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.} } @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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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} }