%0 Journal Article %D Submitted %T Realization of portable room temperature nanodiamond 13C hyperpolarizer %A A. Ajoy %A R. Nazaryan %A E. Druga %A K. Liu %A B. Han %A J.T. Oon %A M. Gierth %A R. Tsang %A J.H. Walton %A C.A. Meriles %A J.A. Reimer %A D. Suter %A A. Pines %G eng %0 Journal Article %J Nano Letters %D In Press %T Two-electron-spin ratchets as a platform for microwave-free dynamic nuclear polarization of arbitrary material targets %A P.R. Zangara %A J. Henshaw %A D. Pagliero %A A. Ajoy %A J. Reimer %A A. Pines %A C. Meriles %B Nano Letters %G eng %0 Journal Article %J Proceedings of the National Academy of Science %D 2019 %T Dynamics of frequency-swept nuclear spin optical pumping in powdered diamond at low magnetic fields %A P.R. Zangara %A S. Dhomkar %A A. Ajoy %A K. Liu %A R. Nazaryan %A D. Pagliero %A D. Suter %A J. Reimer %A A. Pines %A C. Meriles %X

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

%B Proceedings of the National Academy of Science %8 01/2019 %G eng %U https://www.pnas.org/content/early/2019/01/23/1811994116 %R https://doi.org/10.1073/pnas.1811994116 %0 Journal Article %J Nano Letters %D 2019 %T Two-Electron-Spin Ratchets as a Platform for Microwave-Free Dynamic Nuclear Polarization of Arbitrary Material Targets %A Pablo R. Zangara %A J. Henshaw %A Daniela Pagliero %A Ashok Ajoy %A Jeffrey A. Reimer %A Alexander Pines %A Carlos A. Meriles %X

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

%B Nano Letters %8 03/2019 %G eng %U https://pubs.acs.org/doi/full/10.1021/acs.nanolett.8b05114 %R 10.1021/acs.nanolett.8b05114 %0 Journal Article %J Review of Scientific Instruments %D 2019 %T Wide dynamic range magnetic field cycler: Harnessing quantum control at low and high fields %A A. Ajoy %A X. Lv %A E. Druga %A K. Liu %A B. Safvati %A A. Morabe %A M. Fenton %A R. Nazaryan %A S. Patel %A T. Sjolander %A J. Reimer %A D Sakellariou %A C. Meriles %A A. Pines %X

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

%B Review of Scientific Instruments %V 90 %8 01/2019 %G eng %U https://aip.scitation.org/doi/10.1063/1.5064685 %R https://doi.org/10.1063/1.5064685 %0 Journal Article %J Nature Communications %D 2019 %T Zero-Field Nuclear Magnetic Resonance of Chemically Exchanging Systems %A Danila Barskiy %A Michael Tayler %A Irene Marco-Rius %A John Kurhanewicz %A Daniel Vigneron %A Sevil Cikrikci %A Ayca Aydogdu %A Moritz Reh %A Andrey Pravdivtsev %A Jan-Bernd Hövener %A John Blanchard %A Teng Wu %A Dmitry Budker %A Alexander Pines %X

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

%B Nature Communications %V 10 %8 07/2019 %G eng %U https://www.nature.com/articles/s41467-019-10787-9?fbclid=IwAR1MB5nAamCMGynKRk0sjD6V8rTlZ329IvrVKrCwIO8QjrEH4wD23BV5gak %R https://doi.org/10.1038/s41467-019-10787-9 %0 Journal Article %J Proc. Natl. Acad. Sci %D 2018 %T Enhanced dynamic nuclear polarization via swept microwave frequency combs %A Ashok Ajoy %A Kristina Liu %A Xudong Lv %A Raffi Nazaryan %A G.Wang %A E . Druga %A Jeff Reimer %A Ditter Suter %A C. Ramanathan %A C.A Meriles %A Alexander Pines %X

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

%B Proc. Natl. Acad. Sci %8 10/2018 %G eng %U https://doi.org/10.1073/pnas.1807125115 %R 1807125115 %0 Journal Article %J Science Advances %D 2018 %T Orientation independent room-temperature optical 13C hyperpolarization in powdered diamond %A Ashok Ajoy %A Kristina Liu %A Raff Nazaryan %A Xudong Lv %A Pablo R. Zangara %A Benjamin Safvati %A Guoqing Wang %A Daniel Arnold %A Grace Li %A Arthur Lin %A Priyanka Raghavan %A Emanuel Druga %A Siddharth Dhomkar %A Daniela Pagliero %A Jeffrey A. Reimer %A Dieter Suter %A Carlos A. Meriles %A Alexander Pines %X

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

%B Science Advances %V 4 %8 05/2018 %G eng %U http://advances.sciencemag.org/content/4/5/eaar5492 %N 5 %R 10.1126/sciadv.aar5492 %0 Journal Article %J Chemistry - A European Journal %D 2018 %T Selective Single‐Site Pd−In Hydrogenation Catalyst for Production of Enhanced Magnetic Resonance Signals using Parahydrogen %A Dudari Burueva %A Kirill Kovtunov %A Andrey Bukhtiyarov %A Danila Barskiy %A Igor Prosvirin %A Igor Mashkovsky %A Galina Baeva %A Valerii Bukhtiyarov %A Aleksandr Stakheev %A Igor Koptyug %X

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

%B Chemistry - A European Journal %V 24 %8 01/2018 %G eng %U https://onlinelibrary.wiley.com/doi/full/10.1002/chem.201705644 %N 11 %& 2547 %R 10.1002/chem.201705644 %0 Journal Article %J Scientific Reports %D 2017 %T An optimized microfabricated platform for the optical generation and detection of hyperpolarized 129Xe %A Daniel J. Kennedy %A Scott J. Seltzer %A Ricardo Jimenez-Martinez %A Hattie L. Ring %A Nicholas Malecek %A Svenja Knappe %A Elizabeth Donley %A John Kitching %A Vikram S. Bajaj %A Alexander Pines %B Scientific Reports %G eng %U http://www.nature.com/articles/srep43994 %0 Journal Article %J Bioconjugate Chemistry %D 2016 %T Targeted Molecular Imaging of Cancer Cells using MS2-Based 129Xe NMR %A Keunhong Jeong %A Chawita Netirojjanakul %A Henrik K Munch %A Jinny Sun %A Joel A Finbloom %A David E Wemmer %A Alexander Pines %A Matthew B Francis %B Bioconjugate Chemistry %V 27 %8 07/2016 %G eng %U http://pubs.acs.org/doi/abs/10.1021/acs.bioconjchem.6b00275 %N 8 %& 1796 %R 10.1021/acs.bioconjchem.6b00275 %0 Journal Article %J Journal of Magnetic Resonance %D 2014 %T Gradient-free microfluidic flow labeling using thin magnetic films and remotely detected MRI (Cover Article) %A Halpern-Manners, N.W. %A Kennedy, D.J. %A Trease, D.R. %A Teisseyre, T.Z. %A Malecek, N.S. %A Pines, A. %A Bajaj, V.S. %B Journal of Magnetic Resonance %V 249 %P 135-140 %8 12/2014 %G eng %0 Journal Article %J Journal of the American Chemical Society %D 2013 %T Hyperpolarized xenon-based molecular sensors for label-free detection of analytes %A Garimella, Praveena %A Meldrum, Tyler %A Witus, Leah Suzanne %A Smith, Monica %A Bajaj, Vikram %A Wemmer, David E. %A Francis, Matthew B. %A Pines, Alexander %B Journal of the American Chemical Society %V 136 %P 164-168 %8 12/2013 %G eng %R 10.1021/ja406760r %0 Journal Article %J Applied Magnetic Resonance %D 2012 %T Measurement of Arterial Input Function in Hyperpolarized C-13 Studies %A Marjanska, M. %A Teisseyre, T. Z. %A Halpern-Manners, N. W. %A Zhang, Y. %A Iltis, I. %A Bajaj, V. %A Ugurbil, K. %A Pines, A. %A Henry, P. G. %K kinetics %X

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

%B Applied Magnetic Resonance %V 43 %P 289-297 %8 Jul %@ 0937-9347 %G English %U ://WOS:000306421200024 %N 1-2 %M WOS:000306421200024 %! Measurement of Arterial Input Function in Hyperpolarized C-13 Studies %R Doi 10.1007/S00723-012-0348-3 %0 Journal Article %J Journal of Applied Physics %D 2012 %T Room-temperature operation of a radiofrequency diamond magnetometer near the shot-noise limit %A Shin, C. S. %A Avalos, C. E. %A Butler, M. C. %A Trease, D. R. %A Seltzer, S. J. %A Mustonen, J. P. %A Kennedy, D. J. %A Acosta, V. M. %A Budker, D. %A Pines, A. %A Bajaj, V. S. %K spin %X

We operate a nitrogen-vacancy (NV-) diamond magnetometer at ambient temperatures and study the dependence of its bandwidth on experimental parameters including optical and microwave excitation powers. A model based on the Bloch equations is used to analyze the NV center's response time, tau, during continuous optical and microwave irradiation, and tau(-1) is shown to be a weighted average of T-1(-1) and T-2(-1), where T-1 and T-2 are the longitudinal and transverse relaxation times of the electron spin during optical irradiation. We measured a maximum detection bandwidth of similar to 1.6 MHz with optical excitation intensity of similar to 2.3MW/cm(2), limited by the available optical power. The sensitivity of the NV ensemble for continuous-wave magnetometry in the presence of photon shot noise is analyzed. Two detection schemes are compared, one involving modulation of the fluorescence by an oscillating magnetic field while the microwave frequency is held constant, and the other involving double modulation of the fluorescence when the microwave frequency is modulated during the detection. For the first of these methods, we measure a sensitivity of 4.6 +/- 0.3 nT/root Hz, unprecedented in a detector with this active volume of similar to 10 mu m(3) and close to the photon-shot-noise limit of our experiment. The measured bandwidth and sensitivity of our device should allow detection of micro-scale NMR signals with microfluidic devices. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4771924]

%B Journal of Applied Physics %V 112 %P 124519 %8 Dec 15, 2012 %@ 0021-8979 %G English %U http://link.aip.org/link/doi/10.1063/1.4771924 %N 12 %M WOS:000312829400142 %! Room-temperature operation of a radiofrequency diamond magnetometer near the shot-noise limit %& 124519 %R Doi 10.1063/1.4771924 %0 Journal Article %J Journal of Magnetic Resonance %D 2011 %T Band-selective chemical exchange saturation transfer imaging with hyperpolarized xenon-based molecular sensors %A Meldrum, T. %A Bajaj, V. S. %A Wemmer, D. E. %A Pines, A. %K xe-129 %X

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

%B Journal of Magnetic Resonance %V 213 %P 14-21 %8 Dec %@ 1090-7807 %G English %U ://WOS:000296997800002 %N 1 %M WOS:000296997800002 %! Band-selective chemical exchange saturation transfer imaging with hyperpolarized xenon-based molecular sensors %R Doi 10.1016/J.Jmr.2011.06.027 %0 Journal Article %J Magnetic Resonance in Medicine %D 2011 %T Relaxivity of Gadolinium Complexes Detected by Atomic Magnetometry %A Michalak, D. J. %A Xu, S. J. %A Lowery, T. J. %A Crawford, C. W. %A Ledbetter, M. %A Bouchard, L. S. %A Wemmer, D. E. %A Budker, D. %A Pines, A. %K nmr %X

Laser atomic magnetomeby is a portable and low-cost yet highly sensitive method for low magnetic field detection. In this work, the atomic magnetometer was used in a remote-detection geometry to measure the relaxivity of aqueous gadolinium-diethylenetriamine pentaacetic acid Gd(DTPA) at the Earth's magnetic field (40 mu T). The measured relaxivity of 9.7 +/- 2.0 s(-1) mM(-1) is consistent with field-cycling experiments measured at slightly higher magnetic fields, but no cryogens or strong and homogeneous magnetic field were required for this experiment. The field-independent sensitivity of 80 fT Hz(-1/2) allowed an in vitro detection limit of similar to 10 mu M Gd(DTPA) to be measured in aqueous buffer solution. The low detection limit and enhanced relaxivity of Gd-containing complexes at Earth's field motivate continued development of atomic magnetometry toward medical applications. Magn Reson Med 66:605-608, 2011. (C) 2011 Wiley-Liss, Inc.

%B Magnetic Resonance in Medicine %V 66 %P 605-608 %8 Aug %@ 0740-3194 %G English %U ://WOS:000293256800033 %N 2 %M WOS:000293256800033 %! Relaxivity of Gadolinium Complexes Detected by Atomic Magnetometry %R Doi 10.1002/Mrm.22811 %0 Journal Article %J Journal of Chemical Physics %D 2010 %T Investigation of antirelaxation coatings for alkali-metal vapor cells using surface science techniques %A Seltzer, S. J. %A Michalak, D. J. %A Donaldson, M. H. %A Balabas, M. V. %A Barber, S. K. %A Bernasek, S. L. %A Bouchiat, M. A. %A Hexemer, A. %A Hibberd, A. M. %A Kimball, D. F. J. %A Jaye, C. %A Karaulanov, T. %A Narducci, F. A. %A Rangwala, S. A. %A Robinson, H. G. %A Shmakov, A. K. %A Voronov, D. L. %A Yashchuk, V. V. %A Pines, A. %A Budker, D. %K SPECTROSCOPY %X

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

%B Journal of Chemical Physics %V 133 %P 144703 %8 October 11, 2010 %@ 0021-9606 %G English %U http://link.aip.org/link/doi/10.1063/1.3489922 %N 14 %9 Article %M WOS:000283200400049 %] 144703 %! Investigation of antirelaxation coatings for alkali-metal vapor cells using surface science techniques %& 144703 %R 10.1063/1.3489922 %0 Journal Article %J Journal of the American Chemical Society %D 2010 %T A Xenon-Based Molecular Sensor Assembled on an MS2 Viral Capsid Scaffold %A Meldrum, T. %A Seim, K. L. %A Bajaj, V. S. %A Palaniappan, K. K. %A Wu, W. %A Francis, M. B. %A Wemmer, D. E. %A Pines, A. %K nmr %X

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

%B Journal of the American Chemical Society %V 132 %P 5936-+ %8 May 5 %@ 0002-7863 %G English %U ://WOS:000277158500007 %N 17 %M WOS:000277158500007 %! A Xenon-Based Molecular Sensor Assembled on an MS2 Viral Capsid Scaffold %R Doi 10.1021/Ja100319f %0 Journal Article %J Journal of Magnetic Resonance %D 2010 %T Xenon-based molecular sensors in lipid suspensions %A Meldrum, T. %A Schroder, L. %A Denger, P. %A Wemmer, D. E. %A Pines, A. %K binding %X

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

%B Journal of Magnetic Resonance %V 205 %P 242-246 %8 Aug %@ 1090-7807 %G English %U ://WOS:000280064500008 %N 2 %M WOS:000280064500008 %! Xenon-based molecular sensors in lipid suspensions %R Doi 10.1016/J.Jmr.2010.05.005 %0 Journal Article %J Journal of Magnetic Resonance %D 2009 %T Distortion-free magnetic resonance imaging in the zero-field limit %A Kelso, N. %A Lee, S. K. %A Bouchard, L. S. %A Demas, V. %A Mück, M. %A Pines, A. %A Clarke, J. %K gradients %X

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

%B Journal of Magnetic Resonance %V 200 %P 285-290 %8 Oct %@ 1090-7807 %G English %U ://WOS:000272260900015 %N 2 %M WOS:000272260900015 %! Distortion-free magnetic resonance imaging in the zero-field limit %R Doi 10.1016/J.Jmr.2009.07.016 %0 Journal Article %J Chemical Physics Letters %D 2009 %T 'Ex situ' magnetic resonance volume imaging %A Demas, V. %A Franck, J. M. %A Bouchard, L. S. %A Sakellariou, D. %A Meriles, C. A. %A Martin, R. %A Prado, P. J. %A Bussandri, A. %A Reimer, J. A. %A Pines, A. %K array %X

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

%B Chemical Physics Letters %V 467 %P 398-401 %8 Jan 5 %@ 0009-2614 %G English %U ://WOS:000261909700037 %N 4-6 %M WOS:000261909700037 %! 'Ex situ' magnetic resonance volume imaging %R Doi 10.1016/J.Cplett.2008.11.069 %0 Journal Article %J Journal of Chemical Physics %D 2009 %T Shimmed matching pulses: Simultaneous control of rf and static gradients for inhomogeneity correction %A Franck, J. M. %A Demas, V. %A Martin, R. W. %A Bouchard, L. S. %A Pines, A. %K design %X

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

%B Journal of Chemical Physics %V 131 %8 Dec 21 %@ 0021-9606 %G English %U ://WOS:000273036300030 %N 23 %M WOS:000273036300030 %! Shimmed matching pulses: Simultaneous control of rf and static gradients for inhomogeneity correction %R Doi 10.1063/1.3243850 %0 Journal Article %J Journal of Magnetic Resonance Imaging %D 2008 %T Flow in Porous Metallic Materials: A Magnetic Resonance Imaging Study %A Xu, S. J. %A Harel, E. %A Michalak, D. J. %A Crawford, C. W. %A Budker, D. %A Pines, A. %K mri %X

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

%B Journal of Magnetic Resonance Imaging %V 28 %P 1299-1302 %8 Nov %@ 1053-1807 %G English %U ://WOS:000260566100033 %N 5 %M WOS:000260566100033 %! Flow in Porous Metallic Materials: A Magnetic Resonance Imaging Study %R Doi 10.1002/Jmri.21532 %0 Journal Article %J Proceedings of the National Academy of Sciences of the United States of America %D 2008 %T Remote detection of nuclear magnetic resonance with an anisotropic magnetoresistive sensor %A Verpillat, F. %A Ledbetter, M. P. %A Xu, S. %A Michalak, D. J. %A Hilty, C. %A Bouchard, L. S. %A Antonijevic, S. %A Budker, D. %A Pines, A. %K mri %X

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

%B Proceedings of the National Academy of Sciences of the United States of America %V 105 %P 2271-2273 %8 Feb 19 %@ 0027-8424 %G English %U ://WOS:000253469900006 %N 7 %M WOS:000253469900006 %! Remote detection of nuclear magnetic resonance with an anisotropic magnetoresistive sensor %R Doi 10.1073/Pnas.0712129105 %0 Journal Article %J Physical Review Letters %D 2008 %T Temperature response of (129)Xe depolarization transfer and its application for ultrasensitive NMR detection %A Schroeder, L. %A Meldrum, T. %A Smith, M. %A Lowery, T. J. %A Wemmer, D. E. %A Pines, A. %K biosensors %X

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

%B Physical Review Letters %V 100 %8 Jun 27 %@ 0031-9007 %G English %U ://WOS:000257230500066 %N 25 %M WOS:000257230500066 %! Temperature response of (129)Xe depolarization transfer and its application for ultrasensitive NMR detection %R Doi 10.1103/Physrevlett.100.257603 %0 Journal Article %J Angewandte Chemie-International Edition %D 2008 %T Temperature-controlled molecular depolarization gates in nuclear magnetic resonance %A Schroder, L. %A Chavez, L. %A Meldrum, T. %A Smith, M. %A Lowery, T. J. %A Wemmer, D. E. %A Pines, A. %K mri %B Angewandte Chemie-International Edition %V 47 %P 4316-4320 %@ 1433-7851 %G English %U ://WOS:000256364400007 %N 23 %M WOS:000256364400007 %! Temperature-controlled molecular depolarization gates in nuclear magnetic resonance %R Doi 10.1002/Anie.200800382 %0 Journal Article %J Proceedings of the National Academy of Sciences of the United States of America %D 2008 %T Zero-field remote detection of NMR with a microfabricated atomic magnetometer %A Ledbetter, M. P. %A Savukov, I. M. %A Budker, D. %A Shah, V. %A Knappe, S. %A Kitching, J. %A Michalak, D. J. %A Xu, S. %A Pines, A. %K mri %X

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

%B Proceedings of the National Academy of Sciences of the United States of America %V 105 %P 2286-2290 %8 Feb 19 %@ 0027-8424 %G English %U ://WOS:000253469900009 %N 7 %M WOS:000253469900009 %! Zero-field remote detection of NMR with a microfabricated atomic magnetometer %R Doi 10.1073/Pnas.0711505105 %0 Journal Article %J Journal of Magnetic Resonance %D 2007 %T Design and construction of a contactless mobile RF coil for double resonance variable angle spinning NMR %A Qian, C. Q. %A Pines, A. %A Martin, R. W. %K magnetism %X

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

%B Journal of Magnetic Resonance %V 188 %P 183-189 %8 Sep %@ 1090-7807 %G English %U ://WOS:000249750800020 %N 1 %M WOS:000249750800020 %! Design and construction of a contactless mobile RF coil for double resonance variable angle spinning NMR %R Doi 10.1016/J.Jmr.2007.06.006 %0 Journal Article %J Review of Scientific Instruments %D 2007 %T Multipole shimming of permanent magnets using harmonic corrector rings %A Jachmann, R. C. %A Trease, D. R. %A Bouchard, L. S. %A Sakellariou, D. %A Martin, R. W. %A Schlueter, R. D. %A Budinger, T. F. %A Pines, A. %K field %X

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

%B Review of Scientific Instruments %V 78 %8 Mar %@ 0034-6748 %G English %U ://WOS:000245320800056 %N 3 %M WOS:000245320800056 %! Multipole shimming of permanent magnets using harmonic corrector rings %R Doi 10.1063/1.2713438 %0 Journal Article %J Physical Review Letters %D 2007 %T Time-of-flight flow imaging of two-component flow inside a microfluidic chip %A Harel, E. %A Hilty, C. %A Koen, K. %A McDonnell, E. E. %A Pines, A. %K microchannels %X

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

%B Physical Review Letters %V 98 %8 Jan 5 %@ 0031-9007 %G English %U ://WOS:000243379700050 %N 1 %M WOS:000243379700050 %! Time-of-flight flow imaging of two-component flow inside a microfluidic chip %R Doi 10.1103/Physrevlett.98.017601 %0 Journal Article %J Journal of Magnetic Resonance %D 2006 %T Auxiliary probe design adaptable to existing probes for remote detection NMR, MRI, and time-of-flight tracing %A Han, S. I. %A Granwehr, J. %A Garcia, S. %A McDonnell, E. E. %A Pines, A. %K flow %X

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.

%B Journal of Magnetic Resonance %V 182 %P 260-272 %8 Oct %@ 1090-7807 %G English %U ://WOS:000241203900010 %N 2 %M WOS:000241203900010 %! Auxiliary probe design adaptable to existing probes for remote detection NMR, MRI, and time-of-flight tracing %R Doi 10.1016/J.Jmr.2006.06.024 %0 Journal Article %J Solid State Nuclear Magnetic Resonance %D 2006 %T Solid-state NMR structural studies of the fibril form of a mutant mouse prion peptide PrP89-143(P101L) %A Lim, K. H. %A Nguyen, T. N. %A Damo, S. M. %A Mazur, T. %A Ball, H. L. %A Prusiner, S. B. %A Pines, A. %A Wemmer, D. E. %K identification %X

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

%B Solid State Nuclear Magnetic Resonance %V 29 %P 183-190 %8 Feb %@ 0926-2040 %G English %U ://WOS:000234417500020 %N 1-3 %M WOS:000234417500020 %! Solid-state NMR structural studies of the fibril form of a mutant mouse prion peptide PrP89-143(P101L) %R Doi 10.1016/J.Ssnmr.2005.09.017 %0 Journal Article %J Journal of Magnetic Resonance %D 2006 %T SQUID-detected microtesla MRI in the presence of metal %A Mossle, M. %A Han, S. I. %A Myers, W. R. %A Lee, S. K. %A Kelso, N. %A Hatridge, M. %A Pines, A. %A Clarke, J. %K nmr %X

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

%B Journal of Magnetic Resonance %V 179 %P 146-151 %8 Mar %@ 1090-7807 %G English %U ://WOS:000236977600019 %N 1 %M WOS:000236977600019 %! SQUID-detected microtesla MRI in the presence of metal %R Doi 10.1016/J.Jmr.2005.11.005 %0 Journal Article %J Concepts in Magnetic Resonance Part B-Magnetic Resonance Engineering %D 2006 %T Toward ex situ phase-encoded spectroscopic imaging %A Demas, V. %A Meriles, C. %A Sakellariou, D. %A Han, S. I. %A Reimer, J. %A Pines, A. %K probe %X

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

%B Concepts in Magnetic Resonance Part B-Magnetic Resonance Engineering %V 29B %P 137-144 %8 Aug %@ 1552-5031 %G English %U ://WOS:000239298100004 %N 3 %M WOS:000239298100004 %! Toward ex situ phase-encoded spectroscopic imaging %R Doi 10.1002/Cmr.B.20069 %0 Journal Article %J Journal of the American Chemical Society %D 2006 %T Xenon biosensor amplification via dendrimer-cage supramolecular constructs %A Mynar, J. L. %A Lowery, T. J. %A Wemmer, D. E. %A Pines, A. %A Frechet, J. M. J. %K chemistry %B Journal of the American Chemical Society %V 128 %P 6334-6335 %8 May 17 %@ 0002-7863 %G English %U ://WOS:000237590400033 %N 19 %M WOS:000237590400033 %! Xenon biosensor amplification via dendrimer-cage supramolecular constructs %R Doi 10.1021/Ja061735s %0 Journal Article %J Science %D 2005 %T High-resolution NMR spectroscopy with a portable single-sided sensor %A Perlo, J. %A Demas, V. %A Casanova, F. %A Meriles, C. A. %A Reimer, J. %A Pines, A. %A Blumich, B. %K fields %B Science %V 308 %P 1279-1279 %8 May 27 %@ 0036-8075 %G English %U ://WOS:000229482300037 %N 5726 %M WOS:000229482300037 %! High-resolution NMR spectroscopy with a portable single-sided sensor %R Doi 10.1126/Science.1108944 %0 Journal Article %J Magnetic Resonance in Medicine %D 2005 %T High-resolution nuclear magnetic resonance spectroscopy of biological tissues using projected magic angle spinning %A Martin, R. W. %A Jachmann, R. C. %A Sakellariou, D. %A Nielsen, U. G. %A Pines, A. %K field %X

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

%B Magnetic Resonance in Medicine %V 54 %P 253-257 %8 Aug %@ 0740-3194 %G English %U ://WOS:000230765700001 %N 2 %M WOS:000230765700001 %! High-resolution nuclear magnetic resonance spectroscopy of biological tissues using projected magic angle spinning %R Doi 10.1002/Mrm.20585 %0 Journal Article %J Proceedings of the National Academy of Sciences of the United States of America %D 2005 %T Microfluidic gas-flow profiling using remote-detection NMR %A Hilty, C. %A McDonnell, E. E. %A Granwehr, J. %A Pierce, K. L. %A Han, S. I. %A Pines, A. %K mri %X

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.

%B Proceedings of the National Academy of Sciences of the United States of America %V 102 %P 14960-14963 %8 Oct 18 %@ 0027-8424 %G English %U ://WOS:000232811800006 %N 42 %M WOS:000232811800006 %! Microfluidic gas-flow profiling using remote-detection NMR %R Doi 10.1073/Pnas.0507566102 %0 Journal Article %J Analytical Chemistry %D 2005 %T NMR analysis on microfluidic devices by remote detection %A McDonnell, E. E. %A Han, S. L. %A Hilty, C. %A Pierce, K. L. %A Pines, A. %K probes %X

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

%B Analytical Chemistry %V 77 %P 8109-8114 %8 Dec 15 %@ 0003-2700 %G English %U ://WOS:000234079200034 %N 24 %M WOS:000234079200034 %! NMR analysis on microfluidic devices by remote detection %R Doi 10.1021/Ac051320+ %0 Journal Article %J Magnetic Resonance Imaging %D 2005 %T NMR in rotating magnetic fields: magic-angle field spinning %A Sakellariou, D. %A Meriles, C. A. %A Martin, R. W. %A Pines, A. %K samples %X

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

%B Magnetic Resonance Imaging %V 23 %P 295-299 %8 Feb %@ 0730-725X %G English %U ://WOS:000228658400030 %N 2 %M WOS:000228658400030 %! NMR in rotating magnetic fields: magic-angle field spinning %R Doi 10.1016/J.Mri.2004.11.067 %0 Journal Article %J Ieee Transactions on Applied Superconductivity %D 2005 %T SQUID-detected in vivo MRI at microtesla magnetic fields %A Mossle, M. %A Myers, W. R. %A Lee, S. K. %A Kelso, N. %A Hatridge, M. %A Pines, A. %A Clarke, J. %K nmr %X

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

%B Ieee Transactions on Applied Superconductivity %V 15 %P 757-760 %8 Jun %@ 1051-8223 %G English %U ://WOS:000229765300170 %N 2 %M WOS:000229765300170 %! SQUID-detected in vivo MRI at microtesla magnetic fields %R Doi 10.1109/Tasc.2005.850043 %0 Journal Article %J Magnetic Resonance in Medicine %D 2005 %T SQUID-detected MRI at 132 mu T with T(1)-weighted contrast established at 10 mu T-300 mT %A Lee, S. K. %A Mossle, M. %A Myers, W. %A Kelso, N. %A Trabesinger, A. H. %A Pines, A. %A Clarke, J. %K dispersion %X

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

%B Magnetic Resonance in Medicine %V 53 %P 9-14 %8 Jan %@ 0740-3194 %G English %U ://WOS:000226380700003 %N 1 %M WOS:000226380700003 %! SQUID-detected MRI at 132 mu T with T(1)-weighted contrast established at 10 mu T-300 mT %R Doi 10.1002/Mrm.20316 %0 Journal Article %J Actualite Chimique %D 2005 %T Xenon NMR as a probe for microporous and mesoporous solids, polymers, liquid crystals, solutions, flames, proteins, imaging %A Bartik, K. %A Choquet, P. %A Constantinesco, A. %A Duhamel, G. %A Fraissard, J. %A Hyacinthe, J. N. %A Jokisaari, J. %A Locci, E. %A Lowery, T. J. %A Luhmer, M. %A Meersmann, T. %A Moudrakovski, I. L. %A Pavlovskaya, G. E. %A Pierce, K. L. %A Pines, A. %A Ripmeester, J. A. %A Telkki, V. V. %A Veeman, W. S. %K silica-gels %X

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

%B Actualite Chimique %P 16-34 %8 Jun %@ 0151-9093 %G English %U ://WOS:000230991500005 %M WOS:000230991500005 %! Xenon NMR as a probe for microporous and mesoporous solids, polymers, liquid crystals, solutions, flames, proteins, imaging %0 Journal Article %J Proceedings of the National Academy of Sciences of the United States of America %D 2005 %T Zero- to low-field MRI with averaging of concomitant gradient fields %A Meriles, C. A. %A Sakellariou, D. %A Trabesinger, A. H. %A Demas, V. %A Pines, A. %K selection %X

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

%B Proceedings of the National Academy of Sciences of the United States of America %V 102 %P 1840-1842 %8 Feb 8 %@ 0027-8424 %G English %U ://WOS:000227072900009 %N 6 %M WOS:000227072900009 %! Zero- to low-field MRI with averaging of concomitant gradient fields %R Doi 10.1073/Pnas.0409115102 %0 Journal Article %J Comptes Rendus Physique %D 2004 %T Advances in ex-situ Nuclear Magnetic Resonance %A Sakellariou, D. %A Meriles, C. A. %A Pines, A. %K in-vivo %X

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

%B Comptes Rendus Physique %V 5 %P 337-347 %8 Apr %@ 1631-0705 %G English %U ://WOS:000223073800006 %N 3 %M WOS:000223073800006 %! Advances in ex-situ Nuclear Magnetic Resonance %R Doi 10.1016/J.Crhy.2004.03.016 %0 Journal Article %J Journal of Magnetic Resonance %D 2004 %T High-resolution NMR of static samples by rotation of the magnetic field %A Meriles, C. A. %A Sakellariou, D. %A Moule, A. %A Goldman, M. %A Budinger, T. F. %A Pines, A. %K hz %X

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.

%B Journal of Magnetic Resonance %V 169 %P 13-18 %8 Jul %@ 1090-7807 %G English %U ://WOS:000222161900002 %N 1 %M WOS:000222161900002 %! High-resolution NMR of static samples by rotation of the magnetic field %R Doi 10.1016/J.Jmr.2004.03.023 %0 Journal Article %J Journal of Chemical Physics %D 2004 %T Isotropic-liquid crystalline phase diagram of a CdSe nanorod solution %A Li, L. S. %A Marjanska, M. %A Park, G. H. J. %A Pines, A. %A Alivisatos, A. P. %K model %X

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

%B Journal of Chemical Physics %V 120 %P 1149-1152 %8 Jan 15 %@ 0021-9606 %G English %U ://WOS:000188081000002 %N 3 %M WOS:000188081000002 %! Isotropic-liquid crystalline phase diagram of a CdSe nanorod solution %R Doi 10.1063/1.1640331 %0 Journal Article %J Proceedings of the National Academy of Sciences of the United States of America %D 2004 %T Microtesla MRI with a superconducting quantum interference device %A McDermott, R. %A Lee, S. K. %A ten Haken, B. %A Trabesinger, A. H. %A Pines, A. %A Clarke, J. %K system %X

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

%B Proceedings of the National Academy of Sciences of the United States of America %V 101 %P 7857-7861 %8 May 25 %@ 0027-8424 %G English %U ://WOS:000221652000005 %N 21 %M WOS:000221652000005 %! Microtesla MRI with a superconducting quantum interference device %R Doi 10.1073/Pnas.0402382101 %0 Journal Article %J Journal of Physical Chemistry A %D 2004 %T NMR studies of C-13-iodomethane: Different behavior in thermotropic and lyotropic liquid crystals %A Shahkhatuni, A. G. %A Shahkhatuni, A. A. %A Panosyan, H. A. %A Park, G. H. J. %A Martin, R. W. %A Pines, A. %K biomolecules %X

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

%B Journal of Physical Chemistry A %V 108 %P 6809-6813 %8 Aug 19 %@ 1089-5639 %G English %U ://WOS:000223289700001 %N 33 %M WOS:000223289700001 %! NMR studies of C-13-iodomethane: Different behavior in thermotropic and lyotropic liquid crystals %R Doi 10.1021/Jp047330g %0 Journal Article %J Proceedings of the National Academy of Sciences of the United States of America %D 2004 %T "Shim pulses" for NMR spectroscopy and imaging %A Topgaard, D. %A Martin, R. W. %A Sakellariou, D. %A Meriles, C. A. %A Pines, A. %K acquisition %X

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

%B Proceedings of the National Academy of Sciences of the United States of America %V 101 %P 17576-17581 %8 Dec 21 %@ 0027-8424 %G English %U ://WOS:000225951500004 %N 51 %M WOS:000225951500004 %! "Shim pulses" for NMR spectroscopy and imaging %R Doi 10.1073/Pnas.0408296102 %0 Journal Article %J Journal of Physical Chemistry A %D 2004 %T SQUID-detected liquid state NMR in microtesla fields %A Trabesinger, A. H. %A McDermott, R. %A Lee, S. K. %A Mück, M. %A Clarke, J. %A Pines, A. %K water %X

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

%B Journal of Physical Chemistry A %V 108 %P 957-963 %8 Feb 12 %@ 1089-5639 %G English %U ://WOS:000188831500005 %N 6 %M WOS:000188831500005 %! SQUID-detected liquid state NMR in microtesla fields %R Doi 10.1021/Jp035181g %0 Journal Article %J Journal of Low Temperature Physics %D 2004 %T SQUID-detected magnetic resonance imaging in microtesla magnetic fields %A McDermott, R. %A Kelso, N. %A Lee, S. K. %A Mossle, M. %A Mück, M. %A Myers, W. %A ten Haken, B. %A Seton, H. C. %A Trabesinger, A. H. %A Pines, A. %A Clarke, J. %K mri %X

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

%B Journal of Low Temperature Physics %V 135 %P 793-821 %8 Jun %@ 0022-2291 %G English %U ://WOS:000221710600023 %N 5-6 %M WOS:000221710600023 %! SQUID-detected magnetic resonance imaging in microtesla magnetic fields %R Doi 10.1023/B:Jolt.0000029519.09286.C5 %0 Journal Article %J Proceedings of the National Academy of Sciences of the United States of America %D 2004 %T Three-dimensional phase-encoded chemical shift MRI in the presence of inhomogeneous fields %A Demas, V. %A Sakellariou, D. %A Meriles, C. A. %A Han, S. %A Reimer, J. %A Pines, A. %K pulses %X

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

%B Proceedings of the National Academy of Sciences of the United States of America %V 101 %P 8845-8847 %8 Jun 15 %@ 0027-8424 %G English %U ://WOS:000222104900004 %N 24 %M WOS:000222104900004 %! Three-dimensional phase-encoded chemical shift MRI in the presence of inhomogeneous fields %R Doi 10.1073/Pnas.0403016101 %0 Journal Article %J Chemical Physics Letters %D 2004 %T Variable angle spinning (VAS) NMR study of solvent effects in liquid crystalline solutions of C-13-iodomethane %A Park, G. H. J. %A Martin, R. W. %A Sakellariou, D. %A Pines, A. %A Shahkhatuni, A. G. %A Shahkhatuni, A. A. %A Panosyan, H. A. %K phases %X

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

%B Chemical Physics Letters %V 399 %P 196-199 %8 Nov 21 %@ 0009-2614 %G English %U ://WOS:000225324400036 %N 1-3 %M WOS:000225324400036 %! Variable angle spinning (VAS) NMR study of solvent effects in liquid crystalline solutions of C-13-iodomethane %R Doi 10.1016/J.Cplett.2004.10.009 %0 Journal Article %J Proceedings of the National Academy of Sciences of the United States of America %D 2003 %T Amplification of xenon NMR and MRI by remote detection %A Moule, A. J. %A Spence, M. M. %A Han, S. I. %A Seeley, J. A. %A Pierce, K. L. %A Saxena, S. %A Pines, A. %K field %X

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

%B Proceedings of the National Academy of Sciences of the United States of America %V 100 %P 9122-9127 %8 Aug 5 %@ 0027-8424 %G English %U ://WOS:000184620000007 %N 16 %M WOS:000184620000007 %! Amplification of xenon NMR and MRI by remote detection %R Doi 10.1073/Pnas.1133497100 %0 Journal Article %J Journal of Magnetic Resonance %D 2003 %T Broadband phase modulation by adiabatic pulses %A Meriles, C. A. %A Sakellariou, D. %A Pines, A. %K fields %X

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

%B Journal of Magnetic Resonance %V 164 %P 177-181 %8 Sep %@ 1090-7807 %G English %U ://WOS:000185095200023 %N 1 %M WOS:000185095200023 %! Broadband phase modulation by adiabatic pulses %R Doi 10.1016/S1090-7807(03)00157-5 %0 Journal Article %J Journal of the American Chemical Society %D 2003 %T High-resolution NMR correlation spectra of disordered solids %A Sakellariou, D. %A Brown, S. P. %A Lesage, A. %A Hediger, S. %A Bardet, M. %A Meriles, C. A. %A Pines, A. %A Emsley, L. %K SPECTROSCOPY %X

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

%B Journal of the American Chemical Society %V 125 %P 4376-4380 %8 Apr 9 %@ 0002-7863 %G English %U ://WOS:000182003500067 %N 14 %M WOS:000182003500067 %! High-resolution NMR correlation spectra of disordered solids %R Doi 10.1021/Ja0292389 %0 Journal Article %J Chemical Physics Letters %D 2003 %T High-resolution NMR of anisotropic samples with spinning away from the magic angle %A Sakellariou, D. %A Meriles, C. A. %A Martin, R. W. %A Pines, A. %K axis %X

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

%B Chemical Physics Letters %V 377 %P 333-339 %8 Aug 15 %@ 0009-2614 %G English %U ://WOS:000184895200012 %N 3-4 %M WOS:000184895200012 %! High-resolution NMR of anisotropic samples with spinning away from the magic angle %R Doi 10.1016/S0009-2614(03)01149-7 %0 Journal Article %J Journal of Physical Chemistry B %D 2003 %T Inclusion complexes oriented in thermotropic liquid-crystalline solvents studied with carbon-13 NMR %A Marjanska, M. %A Goodson, B. M. %A Castiglione, F. %A Pines, A. %K xe-129 %X

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.

%B Journal of Physical Chemistry B %V 107 %P 12558-12561 %8 Nov 20 %@ 1520-6106 %G English %U ://WOS:000186574500003 %N 46 %M WOS:000186574500003 %! Inclusion complexes oriented in thermotropic liquid-crystalline solvents studied with carbon-13 NMR %R Doi 10.1021/Jp030431e %0 Journal Article %J Journal of the American Chemical Society %D 2003 %T Using switched angle spinning to simplify NMR spectra of strongly oriented samples %A Havlin, R. H. %A Park, G. H. J. %A Mazur, T. %A Pines, A. %K solids %X

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

%B Journal of the American Chemical Society %V 125 %P 7998-8006 %8 Jul 2 %@ 0002-7863 %G English %U ://WOS:000183814500059 %N 26 %M WOS:000183814500059 %! Using switched angle spinning to simplify NMR spectra of strongly oriented samples %R Doi 10.1021/Ja0342244 %0 Journal Article %J Journal of Magnetic Resonance %D 2002 %T Laser-polarized Xe-129 NMR and MRI at ultralow magnetic fields %A Wong-Foy, A. %A Saxena, S. %A Moule, A. J. %A Bitter, H. M. L. %A Seeley, J. A. %A McDermott, R. %A Clarke, J. %A Pines, A. %K atoms %X

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

%B Journal of Magnetic Resonance %V 157 %P 235-241 %8 Aug %@ 1090-7807 %G English %U ://WOS:000178377400009 %N 2 %M WOS:000178377400009 %! Laser-polarized Xe-129 NMR and MRI at ultralow magnetic fields %R Doi 10.1006/Jmre.2002.2592 %0 Journal Article %J Science %D 2002 %T Liquid-state NMR and scalar couplings in microtesla magnetic fields %A McDermott, R. %A Trabesinger, A. H. %A Mück, M. %A Hahn, E. L. %A Pines, A. %A Clarke, J. %K resonance %X

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

%B Science %V 295 %P 2247-2249 %8 Mar 22 %@ 0036-8075 %G English %U ://WOS:000174561700039 %N 5563 %M WOS:000174561700039 %! Liquid-state NMR and scalar couplings in microtesla magnetic fields %R Doi 10.1126/Science.1069280 %0 Journal Article %J Journal of Magnetic Resonance %D 2002 %T Measurement of dipolar couplings in partially oriented molecules by local field NMR spectroscopy with low-power decoupling %A Marjanska, M. %A Castiglione, F. %A Walls, J. D. %A Pines, A. %K resolution %X

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

%B Journal of Magnetic Resonance %V 158 %P 52-59 %8 Sep-Oct %@ 1090-7807 %G English %U ://WOS:000179497500006 %N 1-2 %M WOS:000179497500006 %! Measurement of dipolar couplings in partially oriented molecules by local field NMR spectroscopy with low-power decoupling %R Doi 10.1016/S1090-7807(02)00059-9 %0 Journal Article %J Chemical Physics Letters %D 2002 %T Resolved magic-angle spinning of anisotropic samples in inhomogeneous fields %A Meriles, C. A. %A Sakellariou, D. %A Pines, A. %K pulses %X

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

%B Chemical Physics Letters %V 358 %P 391-395 %8 Jun 7 %@ 0009-2614 %G English %U ://WOS:000176365900005 %N 5-6 %M WOS:000176365900005 %! Resolved magic-angle spinning of anisotropic samples in inhomogeneous fields %R Doi 10.1016/S0009-2614(02)00642-5 %0 Journal Article %J Chemical Physics Letters %D 2002 %T Selective excitation in dipole coupled systems %A Walls, J. D. %A Marjanska, M. %A Sakellariou, D. %A Castiglione, F. %A Pines, A. %K spin-diffusion %X

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

%B Chemical Physics Letters %V 357 %P 241-248 %8 May 10 %@ 0009-2614 %G English %U ://WOS:000175958700012 %N 3-4 %M WOS:000175958700012 %! Selective excitation in dipole coupled systems %R Doi 10.1016/S0009-2614(02)00493-1 %0 Journal Article %J Journal of Magnetic Resonance %D 2002 %T Sensitivity enhancement in multiple-quantum NMR experiments with CPMG detection %A Lim, K. H. %A Nguyen, T. %A Mazur, T. %A Wemmer, D. E. %A Pines, A. %K dynamics %X

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

%B Journal of Magnetic Resonance %V 157 %P 160-162 %8 Jul %@ 1090-7807 %G English %U ://WOS:000177742400019 %N 1 %M WOS:000177742400019 %! Sensitivity enhancement in multiple-quantum NMR experiments with CPMG detection %R Doi 10.1006/Jmre.2002.2578 %0 Journal Article %J Journal of Magnetic Resonance %D 2002 %T Two-dimensional high-resolution NMR spectra in matched B-0 and B-1 field gradients %A Heise, H. %A Sakellariou, D. %A Meriles, C. A. %A Moule, A. %A Pines, A. %K echoes %X

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

%B Journal of Magnetic Resonance %V 156 %P 146-151 %8 May %@ 1090-7807 %G English %U ://WOS:000176562100016 %N 1 %M WOS:000176562100016 %! Two-dimensional high-resolution NMR spectra in matched B-0 and B-1 field gradients %R Doi 10.1006/Jmre.2002.2545 %0 Journal Article %J Chemical Physics Letters %D 2002 %T Variable rotation composite pulses for high resolution nuclear magnetic resonance using inhomogeneous magnetic and radiofrequency fields %A Sakellariou, D. %A Meriles, C. A. %A Moule, A. %A Pines, A. %K echoes %X

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

%B Chemical Physics Letters %V 363 %P 25-33 %8 Sep 2 %@ 0009-2614 %G English %U ://WOS:000177896600005 %N 1-2 %M WOS:000177896600005 %! Variable rotation composite pulses for high resolution nuclear magnetic resonance using inhomogeneous magnetic and radiofrequency fields %R Doi 10.1016/S0009-2614(02)01116-8 %0 Journal Article %J Science %D 2001 %T Approach to high-resolution ex situ NMR spectroscopy %A Meriles, C. A. %A Sakellariou, D. %A Heise, H. %A Moule, A. J. %A Pines, A. %K echoes %X

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

%B Science %V 293 %P 82-85 %8 Jul 6 %@ 0036-8075 %G English %U ://WOS:000169780300032 %N 5527 %M WOS:000169780300032 %! Approach to high-resolution ex situ NMR spectroscopy %R Doi 10.1126/Science.1061498 %0 Journal Article %J Journal of Magnetic Resonance %D 2001 %T Dynamic NMR microscopy of gas phase Poiseuille flow %A Kaiser, L. G. %A Logan, J. W. %A Meersmann, T. %A Pines, A. %K transport %X

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

%B Journal of Magnetic Resonance %V 149 %P 144-148 %8 Mar %@ 1090-7807 %G English %U ://WOS:000168078800021 %N 1 %M WOS:000168078800021 %! Dynamic NMR microscopy of gas phase Poiseuille flow %R Doi 10.1006/Jmre.2000.2283 %0 Journal Article %J Journal of the American Chemical Society %D 2001 %T Resolution of Xe-129 chemical shifts at ultralow magnetic field %A Saxena, S. %A Wong-Foy, A. %A Moule, A. J. %A Seeley, J. A. %A McDermott, R. %A Clarke, J. %A Pines, A. %K adsorption %B Journal of the American Chemical Society %V 123 %P 8133-8134 %8 Aug 22 %@ 0002-7863 %G English %U ://WOS:000170494200027 %N 33 %M WOS:000170494200027 %! Resolution of Xe-129 chemical shifts at ultralow magnetic field %R Doi 10.1021/Ja011064s %0 Journal Article %J Journal of Physical Chemistry A %D 2000 %T Exploring single-file diffusion in one-dimensional nanochannels by laser-polarized Xe-129 NMR spectroscopy (Cover Article) %A Meersmann, T. %A Logan, J. W. %A Simonutti, R. %A Caldarelli, S. %A Comotti, A. %A Sozzani, P. %A Kaiser, L. G. %A Pines, A. %K model %X

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

%B Journal of Physical Chemistry A %V 104 %P 11665-11670 %8 Dec 21 %@ 1089-5639 %G English %U ://WOS:000165869600001 %N 50 %M WOS:000165869600001 %! Exploring single-file diffusion in one-dimensional nanochannels by laser-polarized Xe-129 NMR spectroscopy %R Doi 10.1021/Jp002322v %0 Journal Article %J Angewandte Chemie-International Edition %D 2000 %T A porous crystalline molecular solid explored by hyperpolarized xenon %A Sozzani, P. %A Comotti, A. %A Simonutti, R. %A Meersmann, T. %A Logan, J. W. %A Pines, A. %K c-13 %B Angewandte Chemie-International Edition %V 39 %P 2695-2698 %@ 1433-7851 %G English %U ://WOS:000088702200008 %N 15 %M WOS:000088702200008 %! A porous crystalline molecular solid explored by hyperpolarized xenon %R Doi 10.1002/1521-3773(20000804)39:15<2695::Aid-Anie2695>3.0.Co;2-M %0 Journal Article %J Proceedings of the National Academy of Sciences of the United States of America %D 2000 %T Visualization of gas flow and diffusion in porous media %A Kaiser, L. G. %A Meersmann, T. %A Logan, J. W. %A Pines, A. %K xenon %X

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

%B Proceedings of the National Academy of Sciences of the United States of America %V 97 %P 2414-2418 %8 Mar 14 %@ 0027-8424 %G English %U ://WOS:000085941400005 %N 6 %M WOS:000085941400005 %! Visualization of gas flow and diffusion in porous media %R Doi 10.1073/Pnas.050012497 %0 Journal Article %J Ieee Transactions on Applied Superconductivity %D 1999 %T High-T-c SQUIDs for low-field NMR and MRI of room temperature samples %A Schlenga, K. %A McDermott, R. F. %A Clarke, J. %A de Souza, R. E. %A Wong-Foy, A. %A Pines, A. %K frequencies %X

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

%B Ieee Transactions on Applied Superconductivity %V 9 %P 4424-4427 %8 Jun %@ 1051-8223 %G English %U ://WOS:000081964500386 %N 2 %M WOS:000081964500386 %! High-T-c SQUIDs for low-field NMR and MRI of room temperature samples %R Doi 10.1109/77.784006 %0 Journal Article %J Applied Physics Letters %D 1999 %T Low-field magnetic resonance imaging with a high-T-c dc superconducting quantum interference device %A Schlenga, K. %A McDermott, R. %A Clarke, J. %A de Souza, R. E. %A Wong-Foy, A. %A Pines, A. %K mri %X

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

%B Applied Physics Letters %V 75 %P 3695-3697 %8 Dec 6 %@ 0003-6951 %G English %U ://WOS:000083912800035 %N 23 %M WOS:000083912800035 %! Low-field magnetic resonance imaging with a high-T-c dc superconducting quantum interference device %R Doi 10.1063/1.125432 %0 Journal Article %J Journal of the Brazilian Chemical Society %D 1999 %T NMR and MRI obtained with high transition temperature DC SQUIDs %A de Souza, R. E. %A Schlenga, K. %A Wong-Foy, A. %A McDermott, R. %A Pines, A. %A Clarke, J. %K system %X

We have measured nuclear magnetic resonance (NMR) signals from several samples at room temperature in magnetic fields ranging from about 0.05 mT to 2 mT using a spectrometer based on a high-T-c de SQUID (high transition temperature de Superconducting QUantum Interference Device). We are able to observe proton signals from 1 mL of mineral oil in 2 mT in a single transient. The sensitivity of this system has also allowed the detection of proton NMR at magnetic fields as low as 0.059 mT, which is comparable to the Earth's field. Such results make possible a number of new experiments in magnetic resonance imaging (MRI). We present a two-dimensional image of a phantom filled with mineral oil obtained in a field of 2 mT.

%B Journal of the Brazilian Chemical Society %V 10 %P 307-312 %8 Jul-Aug %@ 0103-5053 %G English %U ://WOS:000083873500009 %N 4 %M WOS:000083873500009 %! NMR and MRI obtained with high transition temperature DC SQUIDs %0 Book %B NMR and MRI of Laser-Polarized Noble Gases in Molecules %D 1999 %T Proc. of the Int. School of Physics, Enrico Fermi Course CXXXIX - Magnetic Resonance and Brain Funtion: Approaches from Physics %A Goodson, B.M. %A Kaiser, L. %A Pines, A. %Y Maraviglia, B. %B NMR and MRI of Laser-Polarized Noble Gases in Molecules %I IOS Press %G eng %! Proc. of the Int. School of Physics, Enrico Fermi Course CXXXIX - Magnetic Resonance and Brain Funtion: Approaches from Physics %& 211-226 %0 Book %B Lectures on Pulsed NMR %D 1998 %T Proc. of the Int. School of Physics, Enrico Fermi Course CXXXIX - Magnetic Resonance and Brain Funtion: Approaches from Physics %A Emsley, L. %A Laws, D. %A Pines, A. %Y Maraviglia, B. %B Lectures on Pulsed NMR %7 3rd %I IOS Press %P 210 %G eng %! Proc. of the Int. School of Physics, Enrico Fermi Course CXXXIX - Magnetic Resonance and Brain Funtion: Approaches from Physics %( 988 %& 45-210 %0 Journal Article %J Journal of Chemical Physics %D 1998 %T Reversal of radio-frequency-driven spin diffusion by reorientation of the sample spinning axis %A De Paul, S. M. %A Tomaselli, M. %A Pines, A. %A Ernst, M. %A Meier, B. H. %K echoes %X

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

%B Journal of Chemical Physics %V 108 %P 826-829 %8 Jan 15 %@ 0021-9606 %G English %U ://WOS:000071487500002 %N 3 %M WOS:000071487500002 %! Reversal of radio-frequency-driven spin diffusion by reorientation of the sample spinning axis %R Doi 10.1063/1.475494 %0 Journal Article %J Molecular Physics %D 1998 %T Time reversal of cross-polarization in solid-state NMR %A Ernst, M. %A Meier, B. H. %A Tomaselli, M. %A Pines, A. %K echoes %X

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

%B Molecular Physics %V 95 %P 849-858 %8 Dec 10 %@ 0026-8976 %G English %U ://WOS:000077460200014 %N 5 %M WOS:000077460200014 %! Time reversal of cross-polarization in solid-state NMR %R Doi 10.1080/002689798166477 %0 Journal Article %J Journal of Chemical Physics %D 1998 %T Time-reversal of cross-polarization in nuclear magnetic resonance %A Ernst, M. %A Meier, B. H. %A Tomaselli, M. %A Pines, A. %K echoes %X

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

%B Journal of Chemical Physics %V 108 %P 9611-9613 %8 Jun 15 %@ 0021-9606 %G English %U ://WOS:000075256100001 %N 23 %M WOS:000075256100001 %! Time-reversal of cross-polarization in nuclear magnetic resonance %R Doi 10.1063/1.476435 %0 Journal Article %J Physics Letters A %D 1997 %T Optical magnetic resonance imaging of Rb vapor in low magnetic fields %A Skalla, J. %A Wackerle, G. %A Mehring, M. %A Pines, A. %K xe-129 %X

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

%B Physics Letters A %V 226 %P 69-74 %8 Feb 10 %@ 0375-9601 %G English %U ://WOS:A1997WF93900012 %N 1-2 %M WOS:A1997WF93900012 %! Optical magnetic resonance imaging of Rb vapor in low magnetic fields %R Doi 10.1016/S0375-9601(96)00927-9 %0 Journal Article %J Chemical Physics Letters %D 1997 %T SQUID detected NMR of laser-polarized xenon at 4.2 K and at frequencies down to 200 Hz %A TonThat, D. M. %A Ziegeweid, M. %A Song, Y. Q. %A Munson, E. J. %A Appelt, S. %A Pines, A. %A Clarke, J. %K relaxation %X

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

%B Chemical Physics Letters %V 272 %P 245-249 %8 Jun 27 %@ 0009-2614 %G English %U ://WOS:A1997XH44000017 %N 3-4 %M WOS:A1997XH44000017 %! SQUID detected NMR of laser-polarized xenon at 4.2 K and at frequencies down to 200 Hz %R Doi 10.1016/S0009-2614(97)88016-5 %0 Journal Article %J Applied Magnetic Resonance %D 1995 %T High-Field Cross-Polarization Nmr from Laser-Polarized Xenon to Surface Nuclei %A Gaede, H. C. %A Song, Y. Q. %A Taylor, R. E. %A Munson, E. J. %A Reimer, J. A. %A Pines, A. %K gel %X

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.

%B Applied Magnetic Resonance %V 8 %P 373-384 %@ 0937-9347 %G English %U ://WOS:A1995RT20200005 %N 3-4 %M WOS:A1995RT20200005 %! High-Field Cross-Polarization Nmr from Laser-Polarized Xenon to Surface Nuclei %0 Journal Article %J Chemistry of Materials %D 1995 %T Xe-129 Nmr-Studies of Hyper-Cross-Linked Polyarylcarbinols - Rigid Versus Flexible Structures %A Urban, C. %A Mccord, E. F. %A Webster, O. W. %A Abrams, L. %A Long, H. W. %A Gaede, H. %A Tang, P. %A Pines, A. %K adsorption %X

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.

%B Chemistry of Materials %V 7 %P 1325-1332 %8 Jul %@ 0897-4756 %G English %U ://WOS:A1995RK99300008 %N 7 %M WOS:A1995RK99300008 %! Xe-129 Nmr-Studies of Hyper-Cross-Linked Polyarylcarbinols - Rigid Versus Flexible Structures %R Doi 10.1021/Cm00055a008 %0 Book %B Lectures in Pulsed NMR %D 1994 %T Proceedings of the International School of Physics Enrico Fermi, Course CXXIII 1992 %A Emsley, L. %A Pines, A. %Y Maraviglia, B. %B Lectures in Pulsed NMR %7 2nd %I World Scientific %G eng %! Proceedings of the International School of Physics Enrico Fermi, Course CXIII 1992 %& 123-266 %0 Journal Article %J Chemical Physics Letters %D 1993 %T Squid-Nmr Study of Methyl Quantum Tunneling in a Series of Carboxylic-Acids %A Black, B. %A Majer, G. %A Pines, A. %K nuclear %X

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

%B Chemical Physics Letters %V 201 %P 550-554 %8 Jan 8 %@ 0009-2614 %G English %U ://WOS:A1993KF75400026 %N 5-6 %M WOS:A1993KF75400026 %! Squid-Nmr Study of Methyl Quantum Tunneling in a Series of Carboxylic-Acids %R Doi 10.1016/0009-2614(93)85115-5 %0 Journal Article %J Journal of Physical Chemistry %D 1992 %T Isotropic Chemical-Shifts and Quadrupolar Parameters for O-17 Using Dynamic-Angle Spinning Nmr %A Mueller, K. T. %A Baltisberger, J. H. %A Wooten, E. W. %A Pines, A. %K zeolites %X

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

%B Journal of Physical Chemistry %V 96 %P 7001-7004 %8 Aug 20 %@ 0022-3654 %G English %U ://WOS:A1992JK80700028 %N 17 %M WOS:A1992JK80700028 %! Isotropic Chemical-Shifts and Quadrupolar Parameters for O-17 Using Dynamic-Angle Spinning Nmr %R Doi 10.1021/J100196a028 %0 Journal Article %J Accounts of Chemical Research %D 1992 %T New Angles in Nuclear-Magnetic-Resonance Sample Spinning %A Wooten, E. W. %A Mueller, K. T. %A Pines, A. %K axis %B Accounts of Chemical Research %V 25 %P 209-215 %8 May %@ 0001-4842 %G English %U ://WOS:A1992HU24800001 %N 5 %M WOS:A1992HU24800001 %! New Angles in Nuclear-Magnetic-Resonance Sample Spinning %R Doi 10.1021/Ar00017a001 %0 Journal Article %J Journal of the American Chemical Society %D 1992 %T Rb-87 Dynamic-Angle Spinning Nmr-Spectroscopy of Inorganic Rubidium Salts %A Baltisberger, J. H. %A Gann, S. L. %A Wooten, E. W. %A Chang, T. H. %A Mueller, K. T. %A Pines, A. %K cesium %X

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.

%B Journal of the American Chemical Society %V 114 %P 7489-7493 %8 Sep 9 %@ 0002-7863 %G English %U ://WOS:A1992JM97900023 %N 19 %M WOS:A1992JM97900023 %! Rb-87 Dynamic-Angle Spinning Nmr-Spectroscopy of Inorganic Rubidium Salts %R Doi 10.1021/Ja00045a023 %0 Journal Article %J Physical Review Letters %D 1991 %T High-Field Nmr of Adsorbed Xenon Polarized by Laser Pumping %A Raftery, D. %A Long, H. %A Meersmann, T. %A Grandinetti, P. J. %A Reven, L. %A Pines, A. %K solids %X

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.

%B Physical Review Letters %V 66 %P 584-587 %8 Feb 4 %@ 0031-9007 %G English %U ://WOS:A1991EV89700017 %N 5 %M WOS:A1991EV89700017 %! High-Field Nmr of Adsorbed Xenon Polarized by Laser Pumping %R Doi 10.1103/Physrevlett.66.584 %0 Journal Article %J Journal of the American Chemical Society %D 1991 %T High-Resolution O-17 Nmr of Solid Silicates %A Mueller, K. T. %A Wu, Y. %A Chmelka, B. F. %A Stebbins, J. %A Pines, A. %K spectra %X

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

%B Journal of the American Chemical Society %V 113 %P 32-38 %8 Jan 2 %@ 0002-7863 %G English %U ://WOS:A1991ER08200006 %N 1 %M WOS:A1991ER08200006 %! High-Resolution O-17 Nmr of Solid Silicates %R Doi 10.1021/Ja00001a006 %0 Journal Article %J Physical Review Letters %D 1991 %T Measurement of Xenon Distribution Statistics in Na-a Zeolite Cavities %A Chmelka, B. F. %A Raftery, D. %A Mccormick, A. V. %A Demenorval, L. C. %A Levine, R. D. %A Pines, A. %K fluids %X

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

%B Physical Review Letters %V 66 %P 580-583 %8 Feb 4 %@ 0031-9007 %G English %U ://WOS:A1991EV89700016 %N 5 %M WOS:A1991EV89700016 %! Measurement of Xenon Distribution Statistics in Na-a Zeolite Cavities %R Doi 10.1103/Physrevlett.66.580 %0 Journal Article %J Review of Scientific Instruments %D 1991 %T Nmr Probe for Dynamic-Angle Spinning %A Mueller, K. T. %A Chingas, G. C. %A Pines, A. %K minerals %X

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

%B Review of Scientific Instruments %V 62 %P 1445-1452 %8 Jun %@ 0034-6748 %G English %U ://WOS:A1991FP31200011 %N 6 %M WOS:A1991FP31200011 %! Nmr Probe for Dynamic-Angle Spinning %R Doi 10.1063/1.1142465 %0 Journal Article %J Journal of Magnetic Resonance %D 1991 %T Pure-Absorption-Phase Dynamic-Angle Spinning %A Mueller, K. T. %A Wooten, E. W. %A Pines, A. %K nuclei %B Journal of Magnetic Resonance %V 92 %P 620-627 %8 May %@ 0022-2364 %G English %U ://WOS:A1991FJ10000018 %N 3 %M WOS:A1991FJ10000018 %! Pure-Absorption-Phase Dynamic-Angle Spinning %R Doi 10.1016/0022-2364(91)90359-2 %0 Conference Proceedings %B Proc. of the Conference on Fundamental Aspects of Quantum Theory %D 1990 %T Abelian and non-abelian holonomy in NMR interferometry %A Pines, A. %A Meuller, K.T. %E Anandan, J. %B Proc. of the Conference on Fundamental Aspects of Quantum Theory %I World Scientific Press %G eng %! Abelian and non-abelian holonomy in NMR interferometry %0 Journal Article %J Journal of Magnetic Resonance %D 1990 %T Dynamic-Angle Spinning of Quadrupolar Nuclei %A Mueller, K. T. %A Sun, B. Q. %A Chingas, G. C. %A Zwanziger, J. W. %A Terao, T. %A Pines, A. %B Journal of Magnetic Resonance %V 86 %P 470-487 %8 Feb 15 %@ 0022-2364 %G English %U ://WOS:A1990CU52500003 %N 3 %M WOS:A1990CU52500003 %! Dynamic-Angle Spinning of Quadrupolar Nuclei %R Doi 10.1016/0022-2364(90)90025-5 %0 Journal Article %J Bulletin of Magnetic Resonance %D 1990 %T A suggestion for detecting rotational tunnelling of CD3: Groups by mulitple quantum spectroscopy %A Werner, U. %A Muller-Warmuth, W. %A Pines, A. %B Bulletin of Magnetic Resonance %V 12 %P 9-14 %G eng %N 1/2 %! A suggestion for detecting rotational tunnelling of CD3: Groups by mulitple quantum spectroscopy %0 Journal Article %J Molecular Physics %D 1989 %T Frequency Selective Nmr Pulse Sequences Generated by Iterative Schemes with Multiple Fixed-Points %A Cho, H. %A Mueller, K. T. %A Shaka, A. J. %A Pines, A. %B Molecular Physics %V 67 %P 505-516 %8 Jun 20 %@ 0026-8976 %G English %U ://WOS:A1989AF15100003 %N 3 %M WOS:A1989AF15100003 %! Frequency Selective Nmr Pulse Sequences Generated by Iterative Schemes with Multiple Fixed-Points %R Doi 10.1080/00268978900101251 %0 Journal Article %J Nature %D 1989 %T O-17 Nmr in Solids by Dynamic-Angle Spinning and Double Rotation %A Chmelka, B. F. %A Mueller, K. T. %A Pines, A. %A Stebbins, J. %A Wu, Y. %A Zwanziger, J. W. %B Nature %V 339 %P 42-43 %8 May 4 %@ 0028-0836 %G English %U ://WOS:A1989U445100054 %N 6219 %M WOS:A1989U445100054 %! O-17 Nmr in Solids by Dynamic-Angle Spinning and Double Rotation %R Doi 10.1038/339042a0 %0 Book %D 1988 %T Lectures on pulsed NMR in proceedings of the 100th school of physics Enrico Fermi %A Pines, A. %E Maraviglia, B. %C North Holland, Amsterdam %G eng %! Lectures on pulsed NMR in proceedings of the 100th school of physics Enrico Fermi %& 43-120 %0 Journal Article %J Physics and Chemistry of Minerals %D 1988 %T A Si-29 Nuclear Magnetic-Resonance Study of Silicon-Aluminum Ordering in Leucite and Analcite %A Murdoch, J. B. %A Stebbins, J. F. %A Carmichael, I. S. E. %A Pines, A. %B Physics and Chemistry of Minerals %V 15 %P 370-382 %@ 0342-1791 %G English %U ://WOS:A1988M683200009 %N 4 %M WOS:A1988M683200009 %! A Si-29 Nuclear Magnetic-Resonance Study of Silicon-Aluminum Ordering in Leucite and Analcite %R Doi 10.1007/Bf00311042 %0 Journal Article %J Physical Review Letters %D 1988 %T Study of the Aharonov-Anandan Quantum Phase by Nmr Interferometry %A Suter, D. %A Mueller, K. T. %A Pines, A. %B Physical Review Letters %V 60 %P 1218-1220 %8 Mar 28 %@ 0031-9007 %G English %U ://WOS:A1988M616000003 %N 13 %M WOS:A1988M616000003 %! Study of the Aharonov-Anandan Quantum Phase by Nmr Interferometry %R Doi 10.1103/Physrevlett.60.1218 %0 Journal Article %J Journal of Physical Chemistry %D 1987 %T Effect of Correlated Proton Jumps on the Zero-Field Nmr-Spectrum of Solid P-Toluic Acid %A Jarvie, T. P. %A Thayer, A. M. %A Millar, J. M. %A Pines, A. %B Journal of Physical Chemistry %V 91 %P 2240-2242 %8 Apr 23 %@ 0022-3654 %G English %U ://WOS:A1987H070500006 %N 9 %M WOS:A1987H070500006 %! Effect of Correlated Proton Jumps on the Zero-Field Nmr-Spectrum of Solid P-Toluic Acid %R Doi 10.1021/J100293a006 %0 Journal Article %J Journal of Chemical Physics %D 1987 %T Multiple-Quantum Dynamics in Nmr - a Directed Walk through Liouville Space %A Munowitz, M. %A Pines, A. %A Mehring, M. %B Journal of Chemical Physics %V 86 %P 3172-3182 %8 Mar 15 %@ 0021-9606 %G English %U ://WOS:A1987G442400012 %N 6 %M WOS:A1987G442400012 %! Multiple-Quantum Dynamics in Nmr - a Directed Walk through Liouville Space %R Doi 10.1063/1.452028 %0 Journal Article %J Advances in Chemical Physics %D 1987 %T Principles and Applications of Multiple-Quantum Nmr %A Munowitz, M. %A Pines, A. %B Advances in Chemical Physics %V 66 %P 1-152 %@ 0065-2385 %G English %U ://WOS:A1987F939800001 %M WOS:A1987F939800001 %! Principles and Applications of Multiple-Quantum Nmr %0 Journal Article %J Journal of Chemical Physics %D 1987 %T Theory of Line-Shapes for Zero-Field Nmr in the Presence of Molecular-Motion %A Meier, P. %A Kothe, G. %A Jonsen, P. %A Trecoske, M. %A Pines, A. %B Journal of Chemical Physics %V 87 %P 6867-6876 %8 Dec 15 %@ 0021-9606 %G English %U ://WOS:A1987L166100011 %N 12 %M WOS:A1987L166100011 %! Theory of Line-Shapes for Zero-Field Nmr in the Presence of Molecular-Motion %R Doi 10.1063/1.453381 %0 Journal Article %J Physics and Chemistry of Minerals %D 1986 %T Defects and Short-Range Order in Nepheline Group Minerals - a Si-29 Nuclear-Magnetic-Resonance Study %A Stebbins, J. F. %A Murdoch, J. B. %A Carmichael, I. S. E. %A Pines, A. %B Physics and Chemistry of Minerals %V 13 %P 371-381 %@ 0342-1791 %G English %U ://WOS:A1986E631100003 %N 6 %M WOS:A1986E631100003 %! Defects and Short-Range Order in Nepheline Group Minerals - a Si-29 Nuclear-Magnetic-Resonance Study %0 Journal Article %J Journal of Magnetic Resonance %D 1986 %T High-Resolution Studies of Deuterium by Time-Domain Zero-Field Nqr %A Millar, J. M. %A Thayer, A. M. %A Zimmermann, H. %A Pines, A. %B Journal of Magnetic Resonance %V 69 %P 243-257 %8 Sep %@ 1090-7807 %G English %U ://WOS:A1986E111500005 %N 2 %M WOS:A1986E111500005 %! High-Resolution Studies of Deuterium by Time-Domain Zero-Field Nqr %R Doi 10.1016/0022-2364(86)90076-4 %0 Journal Article %J Physical Review Letters %D 1986 %T Indirect Phase Detection of Nmr Spinor Transitions %A Suter, D. %A Pines, A. %A Mehring, M. %B Physical Review Letters %V 57 %P 242-244 %8 Jul 14 %@ 0031-9007 %G English %U ://WOS:A1986D125600022 %N 2 %M WOS:A1986D125600022 %! Indirect Phase Detection of Nmr Spinor Transitions %R Doi 10.1103/Physrevlett.57.242 %0 Journal Article %J Science %D 1986 %T Multiple-Quantum Nuclear-Magnetic-Resonance Spectroscopy %A Munowitz, M. %A Pines, A. %B Science %V 233 %P 525-531 %8 Aug 1 %@ 0036-8075 %G English %U ://WOS:A1986D339100022 %N 4763 %M WOS:A1986D339100022 %! Multiple-Quantum Nuclear-Magnetic-Resonance Spectroscopy %R Doi 10.1126/Science.233.4763.525 %0 Journal Article %J Review of Scientific Instruments %D 1986 %T New Probe for High-Temperature Nmr-Spectroscopy with Ppm Resolution %A Stebbins, J. F. %A Schneider, E. %A Murdoch, J. B. %A Pines, A. %A Carmichael, I. S. E. %B Review of Scientific Instruments %V 57 %P 39-42 %8 Jan %@ 0034-6748 %G English %U ://WOS:A1986AXA2000010 %N 1 %M WOS:A1986AXA2000010 %! New Probe for High-Temperature Nmr-Spectroscopy with Ppm Resolution %R Doi 10.1063/1.1139115 %0 Journal Article %J Journal of Chemical Physics %D 1986 %T Theory of Chemical-Exchange in Zero-Field Nmr - 2-Site Flips %A Jonsen, P. %A Luzar, M. %A Pines, A. %A Mehring, M. %B Journal of Chemical Physics %V 85 %P 4873-4880 %8 Nov 1 %@ 0021-9606 %G English %U ://WOS:A1986E517600014 %N 9 %M WOS:A1986E517600014 %! Theory of Chemical-Exchange in Zero-Field Nmr - 2-Site Flips %R Doi 10.1063/1.451722 %0 Journal Article %J Zeitschrift Fur Naturforschung Section a-a Journal of Physical Sciences %D 1986 %T Time Domain Zero-Field Nmr and Nqr %A Bielecki, A. %A Zax, D. B. %A Thayer, A. M. %A Millar, J. M. %A Pines, A. %B Zeitschrift Fur Naturforschung Section a-a Journal of Physical Sciences %V 41 %P 440-444 %8 Jan-Feb %@ 0932-0784 %G English %U ://WOS:A1986A635000084 %N 1-2 %M WOS:A1986A635000084 %! Time Domain Zero-Field Nmr and Nqr %0 Journal Article %J Chemical Physics Letters %D 1986 %T Two-Dimensional Zero-Field Nmr and Nqr %A Thayer, A. M. %A Millar, J. M. %A Pines, A. %B Chemical Physics Letters %V 129 %P 55-58 %8 Aug 15 %@ 0009-2614 %G English %U ://WOS:A1986D720000011 %N 1 %M WOS:A1986D720000011 %! Two-Dimensional Zero-Field Nmr and Nqr %R Doi 10.1016/0009-2614(86)80167-1 %0 Journal Article %J Journal of the American Chemical Society %D 1986 %T Zero-Field Nmr of Small-Amplitude Motions in a Polycrystalline Solid %A Millar, J. M. %A Thayer, A. M. %A Zax, D. B. %A Pines, A. %B Journal of the American Chemical Society %V 108 %P 5113-5116 %8 Aug 20 %@ 0002-7863 %G English %U ://WOS:A1986D723800012 %N 17 %M WOS:A1986D723800012 %! Zero-Field Nmr of Small-Amplitude Motions in a Polycrystalline Solid %R Doi 10.1021/Ja00277a012 %0 Journal Article %J Journal of Physical Chemistry %D 1986 %T Zero-Field Nmr of Solid Bis(Mu-Hydrido)Decacarbonyltriosmium %A Zax, D. B. %A Bielecki, A. %A Kulzick, M. A. %A Muetterties, E. L. %A Pines, A. %B Journal of Physical Chemistry %V 90 %P 1065-1069 %8 Mar 13 %@ 0022-3654 %G English %U ://WOS:A1986A502600021 %N 6 %M WOS:A1986A502600021 %! Zero-Field Nmr of Solid Bis(Mu-Hydrido)Decacarbonyltriosmium %R Doi 10.1021/J100278a021 %0 Journal Article %J Journal of Physical Chemistry %D 1986 %T Zero-Field Nuclear-Magnetic-Resonance of a Nematic Liquid-Crystal %A Thayer, A. M. %A Millar, J. M. %A Luzar, M. %A Jarvie, T. P. %A Pines, A. %B Journal of Physical Chemistry %V 90 %P 1577-1581 %8 Apr 10 %@ 0022-3654 %G English %U ://WOS:A1986A860900024 %N 8 %M WOS:A1986A860900024 %! Zero-Field Nuclear-Magnetic-Resonance of a Nematic Liquid-Crystal %R Doi 10.1021/J100399a024 %0 Journal Article %J Nature %D 1985 %T A High-Temperature High-Resolution Nmr-Study of Na-23, Al-27 and Si-29 in Molten Silicates %A Stebbins, J. F. %A Murdoch, J. B. %A Schneider, E. %A Carmichael, I. S. E. %A Pines, A. %B Nature %V 314 %P 250-252 %@ 0028-0836 %G English %U ://WOS:A1985ADT9900039 %N 6008 %M WOS:A1985ADT9900039 %! A High-Temperature High-Resolution Nmr-Study of Na-23, Al-27 and Si-29 in Molten Silicates %R Doi 10.1038/314250a0 %0 Journal Article %J Journal of Chemical Physics %D 1985 %T Multiple-Quantum Dynamics in Solid-State Nmr %A Baum, J. %A Munowitz, M. %A Garroway, A. N. %A Pines, A. %B Journal of Chemical Physics %V 83 %P 2015-2025 %@ 0021-9606 %G English %U ://WOS:A1985AQG3700002 %N 5 %M WOS:A1985AQG3700002 %! Multiple-Quantum Dynamics in Solid-State Nmr %R Doi 10.1063/1.449344 %0 Journal Article %J Journal of Chemical Physics %D 1985 %T Zero-Field Nmr and Nqr with Selective Pulses and Indirect Detection %A Millar, J. M. %A Thayer, A. M. %A Bielecki, A. %A Zax, D. B. %A Pines, A. %B Journal of Chemical Physics %V 83 %P 934-938 %@ 0021-9606 %G English %U ://WOS:A1985AMG3100004 %N 3 %M WOS:A1985AMG3100004 %! Zero-Field Nmr and Nqr with Selective Pulses and Indirect Detection %R Doi 10.1063/1.449419 %0 Journal Article %J Journal of Magnetic Resonance %D 1984 %T Computer-Simulations of Multiple-Quantum Nmr Experiments .1. Nonselective Excitation %A Murdoch, J. B. %A Warren, W. S. %A Weitekamp, D. P. %A Pines, A. %B Journal of Magnetic Resonance %V 60 %P 205-235 %@ 1090-7807 %G English %U ://WOS:A1984TW09600005 %N 2 %M WOS:A1984TW09600005 %! Computer-Simulations of Multiple-Quantum Nmr Experiments .1. Nonselective Excitation %R Doi 10.1016/0022-2364(84)90327-5 %0 Journal Article %J Journal of Magnetic Resonance %D 1984 %T Computer-Simulations of Multiple-Quantum Nmr Experiments .2. Selective Excitation %A Warren, W. S. %A Murdoch, J. B. %A Pines, A. %B Journal of Magnetic Resonance %V 60 %P 236-256 %@ 1090-7807 %G English %U ://WOS:A1984TW09600006 %N 2 %M WOS:A1984TW09600006 %! Computer-Simulations of Multiple-Quantum Nmr Experiments .2. Selective Excitation %R Doi 10.1016/0022-2364(84)90328-7 %0 Journal Article %J Journal of Chemical Physics %D 1984 %T Fourier-Transform Pure Nuclear-Quadrupole Resonance by Pulsed Field Cycling %A Bielecki, A. %A Murdoch, J. B. %A Weitekamp, D. P. %A Zax, D. B. %A Zilm, K. W. %A Zimmermann, H. %A Pines, A. %B Journal of Chemical Physics %V 80 %P 2232-2234 %@ 0021-9606 %G English %U ://WOS:A1984SH43200068 %N 5 %M WOS:A1984SH43200068 %! Fourier-Transform Pure Nuclear-Quadrupole Resonance by Pulsed Field Cycling %R Doi 10.1063/1.446915 %0 Journal Article %J Molecular Physics %D 1984 %T Multiple-Quantum Nmr-Study of Molecular-Structure and Ordering in a Liquid-Crystal %A Sinton, S. W. %A Zax, D. B. %A Murdoch, J. B. %A Pines, A. %B Molecular Physics %V 53 %P 333-362 %@ 0026-8976 %G English %U ://WOS:A1984TQ35100007 %N 2 %M WOS:A1984TQ35100007 %! Multiple-Quantum Nmr-Study of Molecular-Structure and Ordering in a Liquid-Crystal %R Doi 10.1080/00268978400102351 %0 Journal Article %J Journal of Magnetic Resonance %D 1984 %T Nmr Imaging in Solids by Multiple-Quantum Resonance %A Garroway, A. N. %A Baum, J. %A Munowitz, M. G. %A Pines, A. %B Journal of Magnetic Resonance %V 60 %P 337-341 %@ 1090-7807 %G English %U ://WOS:A1984TW09600014 %N 2 %M WOS:A1984TW09600014 %! Nmr Imaging in Solids by Multiple-Quantum Resonance %R Doi 10.1016/0022-2364(84)90336-6 %0 Journal Article %J Journal of the American Chemical Society %D 1981 %T High-Resolution Nmr-Spectra in Inhomogeneous Magnetic-Fields - Application of Total Spin Coherence Transfer Echoes %A Weitekamp, D. P. %A Garbow, J. R. %A Murdoch, J. B. %A Pines, A. %B Journal of the American Chemical Society %V 103 %P 3578-3579 %@ 0002-7863 %G English %U ://WOS:A1981LT87400057 %N 12 %M WOS:A1981LT87400057 %! High-Resolution Nmr-Spectra in Inhomogeneous Magnetic-Fields - Application of Total Spin Coherence Transfer Echoes %R Doi 10.1021/Ja00402a057 %0 Journal Article %J Chemical Physics Letters %D 1980 %T Deuterium Double-Quantum Nmr with Magic Angle Spinning %A Eckman, R. %A Muller, L. %A Pines, A. %B Chemical Physics Letters %V 74 %P 376-378 %@ 0009-2614 %G English %U ://WOS:A1980KH90200041 %N 2 %M WOS:A1980KH90200041 %! Deuterium Double-Quantum Nmr with Magic Angle Spinning %R Doi 10.1016/0009-2614(80)85182-7 %0 Journal Article %J Chemical Physics Letters %D 1980 %T Proton-Enhanced Deuterium Nmr in Rotating Solids %A Muller, L. %A Eckman, R. %A Pines, A. %B Chemical Physics Letters %V 76 %P 149-154 %@ 0009-2614 %G English %U ://WOS:A1980KT85900034 %N 1 %M WOS:A1980KT85900034 %! Proton-Enhanced Deuterium Nmr in Rotating Solids %R Doi 10.1016/0009-2614(80)80625-7 %0 Journal Article %J Physical Review B %D 1979 %T Quantitative Aspects of Deuteron (Spin 1) Spin Decoupling in Solid-State Nmr %A Suwelack, D. %A Mehring, M. %A Pines, A. %B Physical Review B %V 19 %P 238-246 %@ 0163-1829 %G English %U ://WOS:A1979GN68600029 %N 1 %M WOS:A1979GN68600029 %! Quantitative Aspects of Deuteron (Spin 1) Spin Decoupling in Solid-State Nmr %R Doi 10.1103/Physrevb.19.238 %0 Journal Article %J Physical Review B %D 1978 %T Nmr Double-Quantum Spin Decoupling in Solids %A Pines, A. %A Vega, S. %A Mehring, M. %B Physical Review B %V 18 %P 112-125 %@ 1098-0121 %G English %U ://WOS:A1978FL37300014 %N 1 %M WOS:A1978FL37300014 %! Nmr Double-Quantum Spin Decoupling in Solids %R Doi 10.1103/Physrevb.18.112 %0 Journal Article %J Chemical Physics Letters %D 1976 %T Dynamics of Spin Decoupling in Carbon-13-Proton Nmr %A Sinning, G. %A Mehring, M. %A Pines, A. %B Chemical Physics Letters %V 43 %P 382-386 %@ 0009-2614 %G English %U ://WOS:A1976CK65600042 %N 2 %M WOS:A1976CK65600042 %! Dynamics of Spin Decoupling in Carbon-13-Proton Nmr %R Doi 10.1016/0009-2614(76)85325-0 %0 Journal Article %J Physical Review Letters %D 1976 %T New Approach to High-Resolution Proton Nmr in Solids - Deuterium Spin Decoupling by Multiple-Quantum Transitions %A Pines, A. %A Ruben, D. J. %A Vega, S. %A Mehring, M. %B Physical Review Letters %V 36 %P 110-113 %@ 0031-9007 %G English %U ://WOS:A1976BB17100014 %N 2 %M WOS:A1976BB17100014 %! New Approach to High-Resolution Proton Nmr in Solids - Deuterium Spin Decoupling by Multiple-Quantum Transitions %R Doi 10.1103/Physrevlett.36.110 %0 Journal Article %J Zeitschrift Fur Physik B-Condensed Matter %D 1976 %T Nmr Line Broadening in Solids by Slowing down of Spin Fluctuations %A Mehring, M. %A Sinning, G. %A Pines, A. %B Zeitschrift Fur Physik B-Condensed Matter %V 24 %P 73-76 %@ 0722-3277 %G English %U ://WOS:A1976BS16600009 %N 1 %M WOS:A1976BS16600009 %! Nmr Line Broadening in Solids by Slowing down of Spin Fluctuations %R Doi 10.1007/Bf01312875 %0 Journal Article %J Journal of Magnetic Resonance %D 1974 %T Simple Data Acquisition-System for Proton-Enhanced Nuclear Induction Spectroscopy %A Merrick, T. %A Smiriga, S. %A Pines, A. %B Journal of Magnetic Resonance %V 14 %P 270-273 %@ 1090-7807 %G English %U ://WOS:A1974T499800003 %N 3 %M WOS:A1974T499800003 %! Simple Data Acquisition-System for Proton-Enhanced Nuclear Induction Spectroscopy %R Doi 10.1016/0022-2364(74)90283-2 %0 Journal Article %J Advances in Magnetic Resonance %D 1971 %T Spectrometers for multiple pulse NMR %A Ellett, J.D., Jr. %A Gibby, M.G. %A Haeberlen, U. %A Huber, L.M. %A Mehring, M. %A Pines, A. %A Waugh, J.S. %B Advances in Magnetic Resonance %V 5 %P 117-175 %G eng %! Spectrometers for multiple pulse NMR %0 Journal Article %J Journal of Chemical Physics %D 1971 %T Spin-Decoupling in Resolution of Chemical Shifts in Solids by Pulsed Nmr %A Mehring, M. %A Pines, A. %A Rhim, W. K. %A Waugh, J. S. %B Journal of Chemical Physics %V 54 %P 3239-& %@ 0021-9606 %G English %U ://WOS:A1971J184900070 %N 7 %M WOS:A1971J184900070 %! Spin-Decoupling in Resolution of Chemical Shifts in Solids by Pulsed Nmr %R Doi 10.1063/1.1675324