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

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

}, issn = {0027-8424}, doi = { https://doi.org/10.1073/pnas.1811994116 }, url = {https://www.pnas.org/content/early/2019/01/23/1811994116}, author = {P.R. Zangara and S. Dhomkar and A. Ajoy and K. Liu and R. Nazaryan and D. Pagliero and D. Suter and J. Reimer and A. Pines and C. Meriles} } @article {3230, title = {Two-Electron-Spin Ratchets as a Platform for Microwave-Free Dynamic Nuclear Polarization of Arbitrary Material Targets}, journal = {Nano Letters}, year = {2019}, month = {03/2019}, abstract = {

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

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

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

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

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

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

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

}, doi = {1807125115}, url = {https://doi.org/10.1073/pnas.1807125115}, author = {Ashok Ajoy and Kristina Liu and Xudong Lv and Raffi Nazaryan and G.Wang and E . Druga and Jeff Reimer and Ditter Suter and C. Ramanathan and C.A Meriles and Alexander Pines} } @article {2979, title = {Orientation independent room-temperature optical 13C hyperpolarization in powdered diamond}, journal = {Science Advances}, volume = {4}, year = {2018}, month = {05/2018}, abstract = {

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

}, doi = {10.1126/sciadv.aar5492 }, url = {http://advances.sciencemag.org/content/4/5/eaar5492}, author = {Ashok Ajoy and Kristina Liu and Raff Nazaryan and Xudong Lv and Pablo R. Zangara and Benjamin Safvati and Guoqing Wang and Daniel Arnold and Grace Li and Arthur Lin and Priyanka Raghavan and Emanuel Druga and Siddharth Dhomkar and Daniela Pagliero and Jeffrey A. Reimer and Dieter Suter and Carlos A. Meriles and Alexander Pines} } @article {2391, title = {An optimized microfabricated platform for the optical generation and detection of hyperpolarized 129Xe}, journal = {Scientific Reports }, year = {2017}, url = {http://www.nature.com/articles/srep43994}, author = {Daniel J. Kennedy and Scott J. Seltzer and Ricardo Jimenez-Martinez and Hattie L. Ring and Nicholas Malecek and Svenja Knappe and Elizabeth Donley and John Kitching and Vikram S. Bajaj and Alexander Pines} } @article {1474, title = {Genetically encoded reporters for hyperpolarized xenon MRI}, journal = {Nature Chemistry}, volume = {6}, year = {2014}, month = {04/2014}, pages = {629-634}, chapter = {629}, doi = {10.1038/nchem.1934 }, author = {Mikhail G. Shapiro and R. Matthew Ramirez and Lindsay J. Sperling and George Sun and Jinny Sun and Alexander Pines and David V. Schaffer and Vikram S. Bajaj} } @article {1478, title = {Optical hyperpolarization and NMR detection of 129Xe on a microfluidic chip}, journal = {Nature Communication}, volume = {5}, year = {2014}, pages = {3908}, doi = {10.1038/ncomms4908}, author = {Jimenez-Martinez, R. and Kennedy, D. J. and Rosenbluh, M. and Donley, E. A. and Knappe, S. and Seltzer, S. J. and Ring, H. and Bajaj, V.S. and Kitching, J.} } @article {243, title = {HyperCEST detection of a 129Xe-based contrast agent composed of cryptophane-A molecular cages on a bacteriophage scaffold}, journal = {Magnetic Resonance in Medicine}, volume = {69}, year = {2013}, pages = {1245-1252}, author = {Stevens, T.K. and Palaniappan, K.K. and Ramirez, R.M. and Francis, M.B. and Wemmer, D.E. and Pines, A.} } @article {244, title = {Molecular imaging of cancer cells using a bacteriophage-based (129) xe NMR biosensor.}, journal = {Angewandte Chemie-International Edition}, volume = {52}, year = {2013}, pages = {4849-4853}, edition = {2013 Mar 28}, doi = {10.1002/anie.201300170}, author = {Palaniappan, K. K. and Ramirez, R.M. and Bajaj, V.S. and Wemmer, D.E. and Pines, A. and Francis, M.B.} } @article {1095, title = {Nanoemulsion contrast agents with sub-picomolar sensitivity for xenon NMR}, journal = {Journal of the American Chemical Society}, year = {2013}, month = {06/2013}, doi = {10.1021/ja402885q}, author = {Stevens, T. K. and Ramirez, R. M. and Pines, A.} } @article {251, title = {Liquid-State Nuclear Spin Comagnetometers}, journal = {Physical Review Letters}, volume = {108}, year = {2012}, note = {Phys Rev Lett973FATimes Cited:0Cited References Count:36}, month = {Jun 15}, abstract = {

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

}, keywords = {nmr}, isbn = {0031-9007}, doi = {Doi 10.1103/Physrevlett.108.243001}, url = {://WOS:000306342000010}, author = {Ledbetter, M. P. and Pustelny, S. and Budker, D. and Romalis, M. V. and Blanchard, J. W. and Pines, A.} } @article {258, title = {Near-Zero-Field Nuclear Magnetic Resonance}, journal = {Physical Review Letters}, volume = {107}, year = {2011}, note = {Phys Rev Lett813YOTimes Cited:5Cited References Count:26}, month = {Sep 1}, abstract = {

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

}, keywords = {mri}, isbn = {0031-9007}, doi = {Doi 10.1103/Physrevlett.107.107601}, url = {://WOS:000294406600017}, author = {Ledbetter, M. P. and Theis, T. and Blanchard, J. W. and Ring, H. and Ganssle, P. and Appelt, S. and Blumich, B. and Pines, A. and Budker, D.} } @article {260, title = {Investigation of antirelaxation coatings for alkali-metal vapor cells using surface science techniques}, journal = {Journal of Chemical Physics}, volume = {133}, year = {2010}, note = {J. Chem. Phys.ISI Document Delivery No.: 667NNTimes Cited: 6Cited Reference Count: 81Seltzer, S. J. Michalak, D. J. Donaldson, M. H. Balabas, M. V. Barber, S. K. Bernasek, S. L. Bouchiat, M. -A. Hexemer, A. Hibberd, A. M. Kimball, D. F. Jackson Jaye, C. Karaulanov, T. Narducci, F. A. Rangwala, S. A. Robinson, H. G. Shmakov, A. K. Voronov, D. L. Yashchuk, V. V. Pines, A. Budker, D.Office of Science, Office of Basic Energy Sciences, Materials Sciences Division and Nuclear Science Division, of the U. S. Department of Energy [DE-AC02-05CH11231]; NSF/DST [PHY-0425916]; Office of Naval Research (ONR) [N0001409WX21049]The authors thank Daniel Fischer, Kristin Schmidt, and Ed Kramer for assistance with the NEXAFS measurements, and Joel Ager, Joshua Wnuk, David Trease, and Gwendal Kervern for helpful discussions and other assistance. S.J.S., D.J.M., M. H. D., A. P., and D. B., the Advanced Light Source, and the DSC, FTIR, and AFM studies were supported by the Director, Office of Science, Office of Basic Energy Sciences, Materials Sciences Division and Nuclear Science Division, of the U. S. Department of Energy under Contract No. DE-AC02-05CH11231 at Lawrence Berkeley National Laboratory. Other parts of this work were funded by the NSF/DST under Grant No. PHY-0425916 for U.S.-India cooperative research, by an Office of Naval Research (ONR) MURI grant, and by ONR under Grant No. N0001409WX21049.AMER INST PHYSICSMELVILLE}, month = {October 11, 2010}, pages = {144703}, type = {Article}, chapter = {144703}, abstract = {

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

}, keywords = {SPECTROSCOPY}, isbn = {0021-9606}, doi = {10.1063/1.3489922}, url = {http://link.aip.org/link/doi/10.1063/1.3489922}, author = {Seltzer, S. J. and Michalak, D. J. and Donaldson, M. H. and Balabas, M. V. and Barber, S. K. and Bernasek, S. L. and Bouchiat, M. A. and Hexemer, A. and Hibberd, A. M. and Kimball, D. F. J. and Jaye, C. and Karaulanov, T. and Narducci, F. A. and Rangwala, S. A. and Robinson, H. G. and Shmakov, A. K. and Voronov, D. L. and Yashchuk, V. V. and Pines, A. and Budker, D.} } @article {271, title = {{\textquoteright}Ex situ{\textquoteright} magnetic resonance volume imaging}, journal = {Chemical Physics Letters}, volume = {467}, year = {2009}, note = {Chem Phys Lett386VCTimes Cited:2Cited References Count:25}, month = {Jan 5}, pages = {398-401}, abstract = {

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

}, keywords = {array}, isbn = {0009-2614}, doi = {Doi 10.1016/J.Cplett.2008.11.069}, url = {://WOS:000261909700037}, author = {Demas, V. and Franck, J. M. and Bouchard, L. S. and Sakellariou, D. and Meriles, C. A. and Martin, R. and Prado, P. J. and Bussandri, A. and Reimer, J. A. and Pines, A.} } @article {274, title = {Submillimeter-resolution magnetic resonance imaging at the Earth{\textquoteright}s magnetic field with an atomic magnetometer}, journal = {Physical Review A}, volume = {78}, year = {2008}, note = {Phys Rev A333VGTimes Cited:18Cited References Count:24}, month = {Jul}, abstract = {

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

}, keywords = {nmr}, isbn = {1050-2947}, doi = {Doi 10.1103/Physreva.78.013404}, url = {://WOS:000258180300141}, author = {Xu, S. and Crawford, C. W. and Rochester, S. and Yashchuk, V. and Budker, D. and Pines, A.} } @article {293, title = {Application of atomic magnetometry in magnetic particle detection}, journal = {Applied Physics Letters}, volume = {89}, year = {2006}, note = {Appl Phys Lett112PJTimes Cited:9Cited References Count:18}, month = {Nov 27}, abstract = {

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

}, keywords = {system}, isbn = {0003-6951}, doi = {Doi 10.1063/1.2400077}, url = {://WOS:000242538500151}, author = {Xu, S. and Donaldson, M. H. and Pines, A. and Rochester, S. M. and Budker, D. and Yashchuk, V. V.} } @article {295, title = {Diastereomeric Xe chemical shifts in tethered cryptophane cages}, journal = {Journal of the American Chemical Society}, volume = {128}, year = {2006}, note = {J Am Chem Soc118KQTimes Cited:14Cited References Count:42}, month = {Dec 27}, pages = {16980-16988}, abstract = {

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

}, keywords = {chirality}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja066661z}, url = {://WOS:000242941600104}, author = {Ruiz, E. J. and Sears, D. N. and Pines, A. and Jameson, C. J.} } @article {292, title = {Magnetic resonance imaging with an optical atomic magnetometer}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {103}, year = {2006}, note = {P Natl Acad Sci USA077NITimes Cited:58Cited References Count:18}, month = {Aug 22}, pages = {12668-12671}, abstract = {

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

}, keywords = {gas}, isbn = {0027-8424}, doi = {Doi 10.1073/Pnas.0605396103}, url = {://WOS:000240035900006}, author = {Xu, S. J. and Yashchuk, V. V. and Donaldson, M. H. and Rochester, S. M. and Budker, D. and Pines, A.} } @article {299, title = {Optimization of xenon biosensors for detection of protein interactions}, journal = {Chembiochem}, volume = {7}, year = {2006}, note = {Chembiochem003SDTimes Cited:39Cited References Count:25}, month = {Jan}, pages = {65-73}, abstract = {

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

}, keywords = {complexes}, isbn = {1439-4227}, doi = {Doi 10.1002/Cbic.200500327}, url = {://WOS:000234701000012}, author = {Lowery, T. J. and Garcia, S. and Chavez, L. and Ruiz, E. J. and Wu, T. and Brotin, T. and Dutasta, J. P. and King, D. S. and Schultz, P. G. and Pines, A. and Wemmer, D. E.} } @article {305, title = {Toward ex situ phase-encoded spectroscopic imaging}, journal = {Concepts in Magnetic Resonance Part B-Magnetic Resonance Engineering}, volume = {29B}, year = {2006}, note = {Concept Magn Reson B067JNTimes Cited:7Cited References Count:20}, month = {Aug}, pages = {137-144}, abstract = {

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

}, keywords = {probe}, isbn = {1552-5031}, doi = {Doi 10.1002/Cmr.B.20069}, url = {://WOS:000239298100004}, author = {Demas, V. and Meriles, C. and Sakellariou, D. and Han, S. I. and Reimer, J. and Pines, A.} } @article {313, title = {Distinguishing multiple chemotaxis Y protein conformations with laser-polarized Xe-129 NMR}, journal = {Protein Science}, volume = {14}, year = {2005}, note = {Protein Sci907SSTimes Cited:23Cited References Count:27}, month = {Apr}, pages = {848-855}, abstract = {

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

}, keywords = {cavity}, isbn = {0961-8368}, doi = {Doi 10.1110/Ps.041231005}, url = {://WOS:000227738900002}, author = {Lowery, T. J. and Doucleff, M. and Ruiz, E. J. and Rubin, S. M. and Pines, A. and Wemmer, D. E.} } @article {308, title = {High-resolution NMR spectroscopy with a portable single-sided sensor}, journal = {Science}, volume = {308}, year = {2005}, note = {Science931JTTimes Cited:89Cited References Count:7}, month = {May 27}, pages = {1279-1279}, keywords = {fields}, isbn = {0036-8075}, doi = {Doi 10.1126/Science.1108944}, url = {://WOS:000229482300037}, author = {Perlo, J. and Demas, V. and Casanova, F. and Meriles, C. A. and Reimer, J. and Pines, A. and Blumich, B.} } @article {317, title = {NMR-based biosensing with optimized delivery of polarized Xe-129 to solutions}, journal = {Analytical Chemistry}, volume = {77}, year = {2005}, note = {Anal Chem942GLTimes Cited:30Cited References Count:37}, month = {Jul 1}, pages = {4008-4012}, abstract = {

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

}, keywords = {blood}, isbn = {0003-2700}, doi = {Doi 10.1021/Ac0500479}, url = {://WOS:000230270800035}, author = {Han, S. I. and Garcia, S. and Lowery, T. J. and Ruiz, E. J. and Seeley, J. A. and Chavez, L. and King, D. S. and Wemmer, D. E. and Pines, A.} } @article {320, title = {Xenon NMR as a probe for microporous and mesoporous solids, polymers, liquid crystals, solutions, flames, proteins, imaging}, journal = {Actualite Chimique}, year = {2005}, note = {Actual ChimiqueSuppl. 287952GHTimes Cited:3Cited References Count:89}, month = {Jun}, pages = {16-34}, abstract = {

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

}, keywords = {silica-gels}, isbn = {0151-9093}, url = {://WOS:000230991500005}, author = {Bartik, K. and Choquet, P. and Constantinesco, A. and Duhamel, G. and Fraissard, J. and Hyacinthe, J. N. and Jokisaari, J. and Locci, E. and Lowery, T. J. and Luhmer, M. and Meersmann, T. and Moudrakovski, I. L. and Pavlovskaya, G. E. and Pierce, K. L. and Pines, A. and Ripmeester, J. A. and Telkki, V. V. and Veeman, W. S.} } @article {333, title = {Design of a conformation-sensitive xenon-binding cavity in the ribose-binding protein}, journal = {Angewandte Chemie-International Edition}, volume = {43}, year = {2004}, note = {Angew Chem Int Edit877MVTimes Cited:10Cited References Count:20}, pages = {6320-6322}, keywords = {probe}, isbn = {1433-7851}, doi = {Doi 10.1002/Anie.200460629}, url = {://WOS:000225575600015}, author = {Lowery, T. J. and Rubin, S. M. and Ruiz, E. J. and Pines, A. and Wemmer, D. E.} } @article {325, title = {Development of a functionalized xenon biosensor}, journal = {Journal of the American Chemical Society}, volume = {126}, year = {2004}, note = {J Am Chem Soc872UHTimes Cited:60Cited References Count:76}, month = {Nov 24}, pages = {15287-15294}, abstract = {

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

}, keywords = {drug discovery}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja0483037}, url = {://WOS:000225233600051}, author = {Spence, M. M. and Ruiz, E. J. and Rubin, S. M. and Lowery, T. J. and Winssinger, N. and Schultz, P. G. and Wemmer, D. E. and Pines, A.} } @article {321, title = {Hyperpolarized xenon nuclear spins detected by optical atomic magnetometry}, journal = {Physical Review Letters}, volume = {93}, year = {2004}, note = {Phys Rev Lett863ATTimes Cited:32Cited References Count:22}, month = {Oct 15}, abstract = {

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

}, keywords = {mri}, isbn = {0031-9007}, doi = {Doi 10.1103/Physrevlett.93.160801}, url = {://WOS:000224533300012}, author = {Yashchuk, V. V. and Granwehr, J. and Kimball, D. F. and Rochester, S. M. and Trabesinger, A. H. and Urban, J. T. and Budker, D. and Pines, A.} } @article {336, title = {Three-dimensional phase-encoded chemical shift MRI in the presence of inhomogeneous fields}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {101}, year = {2004}, note = {P Natl Acad Sci USA830EQTimes Cited:18Cited References Count:12}, month = {Jun 15}, pages = {8845-8847}, abstract = {

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

}, keywords = {pulses}, isbn = {0027-8424}, doi = {Doi 10.1073/Pnas.0403016101}, url = {://WOS:000222104900004}, author = {Demas, V. and Sakellariou, D. and Meriles, C. A. and Han, S. and Reimer, J. and Pines, A.} } @article {343, title = {Applications of Laser-Polarized 129 XE NMR to Biomolecular Assays}, journal = {Magnetic Resonance Imaging}, year = {2003}, pages = {1235-1239}, doi = {10.1016/J.Mri.2003.08.025}, author = {Lowery, T.J. and Rubin, S.M. and Ruiz, E.J. and Spence, M.M. and Winssinger, N. and Schultz, P.G. and Pines, A. and Wemmer, D.E.} } @article {354, title = {Detection and characterization of xenon-binding sites in proteins by Xe-129 NMR spectroscopy}, journal = {Journal of Molecular Biology}, volume = {322}, year = {2002}, note = {J Mol Biol597PTTimes Cited:53Cited References Count:54}, month = {Sep 13}, pages = {425-440}, abstract = {

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

}, keywords = {nonpolar cavity}, isbn = {0022-2836}, doi = {Doi 10.1016/S0022-2836(02)00739-8}, url = {://WOS:000178230500014}, author = {Rubin, S. M. and Lee, S. Y. and Ruiz, E. J. and Pines, A. and Wemmer, D. E.} } @article {366, title = {Characterization of the effects of nonspecific xenon-protein interactions on Xe-129 chemical shifts in aqueous solution: Further development of xenon as a biomolecular probe}, journal = {Journal of Magnetic Resonance}, volume = {152}, year = {2001}, note = {J Magn Reson472QDTimes Cited:37Cited References Count:34}, month = {Sep}, pages = {79-86}, abstract = {

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

}, keywords = {gas}, isbn = {1090-7807}, doi = {Doi 10.1006/Jmre.2001.2389}, url = {://WOS:000170995700009}, author = {Rubin, S. M. and Spence, M. M. and Pines, A. and Wemmer, D. E.} } @article {367, title = {Detection of a conformational change in maltose binding protein by Xe-129 NMR spectroscopy}, journal = {Journal of the American Chemical Society}, volume = {123}, year = {2001}, note = {J Am Chem Soc467XNTimes Cited:28Cited References Count:28}, month = {Sep 5}, pages = {8616-8617}, keywords = {blood}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja0110325}, url = {://WOS:000170729200029}, author = {Rubin, S. M. and Spence, M. M. and Dimitrov, I. E. and Ruiz, E. J. and Pines, A. and Wemmer, D. E.} } @article {364, title = {Functionalized xenon as a biosensor}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {98}, year = {2001}, note = {P Natl Acad Sci USA472CZTimes Cited:112Cited References Count:29}, month = {Sep 11}, pages = {10654-10657}, abstract = {

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

}, keywords = {mri}, isbn = {0027-8424}, doi = {Doi 10.1073/Pnas.191368398}, url = {://WOS:000170966800030}, author = {Spence, M. M. and Rubin, S. M. and Dimitrov, I. E. and Ruiz, E. J. and Wemmer, D. E. and Pines, A. and Yao, S. Q. and Tian, F. and Schultz, P. G.} } @article {375, title = {Evidence of nonspecific surface interactions between laser-polarized xenon and myoglobin in solution}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {97}, year = {2000}, note = {P Natl Acad Sci USA345XMTimes Cited:40Cited References Count:35}, month = {Aug 15}, pages = {9472-9475}, abstract = {

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

}, keywords = {binding}, isbn = {0027-8424}, doi = {Doi 10.1073/Pnas.170278897}, url = {://WOS:000088840500026}, author = {Rubin, S. M. and Spence, M. M. and Goodson, B. M. and Wemmer, D. E. and Pines, A.} } @proceedings {389, title = {Enhanced Surface NMR of Zeolites and Related Material Using Laser-Polarized Xenon}, journal = {Proc. 12th Int. Zeolite Conf.}, year = {1999}, pages = {2943-2950}, author = {Brunner, E. and Haake, M. and Pines, A. and Reimer, J. and Seydoux, R.} } @article {390, title = {Gas flow MRI using circulating laser-polarized Xe-129}, journal = {Journal of Magnetic Resonance}, volume = {138}, year = {1999}, note = {J Magn Reson196HXTimes Cited:35Cited References Count:15}, month = {May}, pages = {155-159}, abstract = {

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

}, keywords = {xenon}, isbn = {1090-7807}, doi = {Doi 10.1006/Jmre.1998.1675}, url = {://WOS:000080303900021}, author = {Brunner, E. and Haake, M. and Kaiser, L. and Pines, A. and Reimer, J. A.} } @article {381, title = {NMR with a continuously circulating flow of laser-polarized Xe-129}, journal = {Journal of Physical Chemistry B}, volume = {103}, year = {1999}, note = {J Phys Chem B203HNTimes Cited:45Cited References Count:35}, month = {Jun 3}, pages = {4629-4637}, abstract = {

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

}, keywords = {zeolites}, isbn = {1089-5647}, doi = {Doi 10.1021/Jp9821984}, url = {://WOS:000080702600011}, author = {Seydoux, R. and Pines, A. and Haake, M. and Reimer, J. A.} } @article {388, title = {Relaxation-selective magnetic resonance imaging}, journal = {Chemical Physics Letters}, volume = {311}, year = {1999}, note = {Chem Phys Lett244VRTimes Cited:1Cited References Count:15}, month = {Oct 1}, pages = {379-384}, abstract = {

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

}, keywords = {optimization}, isbn = {0009-2614}, doi = {Doi 10.1016/S0009-2614(99)00890-8}, url = {://WOS:000083071900007}, author = {Bush, S. D. and Rourke, D. E. and Kaiser, L. G. and Pines, A.} } @article {404, title = {Enhancement of C-13 NMR signals in solid C-60 and C-70 using laser-polarized xenon}, journal = {Chemical Physics Letters}, volume = {290}, year = {1998}, note = {Chem Phys LettZw963Times Cited:30Cited References Count:31}, month = {Jun 26}, pages = {112-116}, abstract = {

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

}, keywords = {c60}, isbn = {0009-2614}, doi = {Doi 10.1016/S0009-2614(98)00473-4}, url = {://WOS:000074466600018}, author = {Brunner, E. and Haake, M. and Pines, A. and Reimer, J. A. and Seydoux, R.} } @article {402, title = {A high-resolution(17)O NMR study of siliceous zeolite faujasite}, journal = {Journal of the American Chemical Society}, volume = {120}, year = {1998}, note = {J Am Chem SocZj097Times Cited:66Cited References Count:19}, month = {Apr 15}, pages = {3510-3511}, keywords = {workstation computers}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja9743001}, url = {://WOS:000073179200032}, author = {Bull, L. M. and Cheetham, A. K. and Anupold, T. and Reinhold, A. and Samoson, A. and Sauer, J. and Bussemer, B. and Lee, Y. and Gann, S. and Shore, J. and Pines, A. and Dupree, R.} } @article {403, title = {Surface NMR using laser-polarized (129)Xe under magic angle spinning conditions}, journal = {Journal of Magnetic Resonance}, volume = {130}, year = {1998}, note = {J Magn ResonZc833Times Cited:46Cited References Count:21}, month = {Jan}, pages = {145-148}, abstract = {

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

}, keywords = {flow}, isbn = {1090-7807}, doi = {Doi 10.1006/Jmre.1997.1296}, url = {://WOS:000072622700022}, author = {Brunner, E. and Seydoux, R. and Haake, M. and Pines, A. and Reimer, J. A.} } @article {411, title = {Enhancement of surface NMR by laser-polarized noble gases}, journal = {Physical Review B}, volume = {55}, year = {1997}, note = {Phys Rev BWy504Times Cited:65Cited References Count:34}, month = {May 1}, pages = {11604-11610}, abstract = {

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

}, keywords = {he-3}, isbn = {0163-1829}, doi = {Doi 10.1103/Physrevb.55.11604}, url = {://WOS:A1997WY50400096}, author = {Room, T. and Appelt, S. and Seydoux, R. and Hahn, E. L. and Pines, A.} } @article {413, title = {P-31 to Se-77 cross polarization in beta-P4Se3}, journal = {Solid State Nuclear Magnetic Resonance}, volume = {8}, year = {1997}, note = {Solid State Nucl MagYd904Times Cited:7Cited References Count:12}, month = {Aug}, pages = {265-267}, abstract = {

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

}, keywords = {f-19}, isbn = {0926-2040}, doi = {Doi 10.1016/S0926-2040(97)00012-X}, url = {://WOS:A1997YD90400008}, author = {Pietrass, T. and Seydoux, R. and Roth, R. E. and Eckert, H. and Pines, A.} } @article {419, title = {Surface-enhanced NMR using continuous-flow laser-polarized xenon}, journal = {Journal of the American Chemical Society}, volume = {119}, year = {1997}, note = {J Am Chem SocYk502Times Cited:66Cited References Count:16}, month = {Dec 3}, pages = {11711-11712}, keywords = {solids}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja9713587}, url = {://WOS:A1997YK50200029}, author = {Haake, M. and Pines, A. and Reimer, J. A. and Seydoux, R.} } @article {426, title = {Enhancement of solution NMR and MRI with laser-polarized xenon}, journal = {Science}, volume = {271}, year = {1996}, note = {ScienceUc778Times Cited:230Cited References Count:41}, month = {Mar 29}, pages = {1848-1851}, abstract = {

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

}, keywords = {resonance}, isbn = {0036-8075}, doi = {Doi 10.1126/Science.271.5257.1848}, url = {://WOS:A1996UC77800041}, author = {Navon, G. and Song, Y. Q. and Room, T. and Appelt, S. and Taylor, R. E. and Pines, A.} } @article {425, title = {Si-29 high resolution solid state nuclear magnetic resonance spectroscopy of porous silicon}, journal = {Journal of Non-Crystalline Solids}, volume = {202}, year = {1996}, note = {J Non-Cryst SolidsVe406Times Cited:13Cited References Count:33}, month = {Jul}, pages = {68-76}, abstract = {

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

}, keywords = {dipolar}, isbn = {0022-3093}, doi = {Doi 10.1016/0022-3093(96)00144-5}, url = {://WOS:A1996VE40600008}, author = {Pietrass, T. and Bifone, A. and Roth, R. D. and Koch, V. P. and Alivisatos, A. P. and Pines, A.} } @article {453, title = {High-Field Cross-Polarization Nmr from Laser-Polarized Xenon to Surface Nuclei}, journal = {Applied Magnetic Resonance}, volume = {8}, year = {1995}, note = {Appl Magn ResonRt202Times Cited:30Cited References Count:17}, pages = {373-384}, abstract = {

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

}, keywords = {gel}, isbn = {0937-9347}, url = {://WOS:A1995RT20200005}, author = {Gaede, H. C. and Song, Y. Q. and Taylor, R. E. and Munson, E. J. and Reimer, J. A. and Pines, A.} } @article {442, title = {Monitoring Xenon Clathrate Hydrate Formation on Ice Surfaces with Optically Enhanced Xe-129 Nmr}, journal = {Journal of the American Chemical Society}, volume = {117}, year = {1995}, note = {J Am Chem SocRk426Times Cited:60Cited References Count:41}, month = {Jul 19}, pages = {7520-7525}, abstract = {

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

}, keywords = {field}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja00133a025}, url = {://WOS:A1995RK42600025}, author = {Pietrass, T. and Gaede, H. C. and Bifone, A. and Pines, A. and Ripmeester, J. A.} } @article {440, title = {Orientation and Motion of Tetrahydrofuran in Graphite-Intercalation Compounds - Proton Nmr-Studies of Cs(Thf)(1.3)C-24 and K(Thf)(2.5)C-24}, journal = {Journal of Physical Chemistry}, volume = {99}, year = {1995}, note = {J Phys Chem-UsRg562Times Cited:5Cited References Count:31}, month = {Jun 29}, pages = {10565-10572}, abstract = {

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

}, keywords = {system}, isbn = {0022-3654}, doi = {Doi 10.1021/J100026a020}, url = {://WOS:A1995RG56200020}, author = {Schmidt, C. and Rosen, M. E. and Caplan, D. F. and Pines, A. and Quinton, M. F.} } @article {459, title = {Multiple-Pulse Nuclear-Magnetic-Resonance of Optically Pumped Xenon in a Low Magnetic-Field}, journal = {Physical Review A}, volume = {50}, year = {1994}, note = {Phys Rev ANx001Times Cited:23Cited References Count:38}, month = {Jul}, pages = {567-574}, abstract = {

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

}, keywords = {ne-21}, isbn = {1050-2947}, doi = {Doi 10.1103/Physreva.50.567}, url = {://WOS:A1994NX00100070}, author = {Raftery, D. and Long, H. W. and Shykind, D. and Grandinetti, P. J. and Pines, A.} } @article {473, title = {2-Dimensional Proton Nmr-Studies of the Conformations and Orientations of N-Alkanes in a Liquid-Crystal Solvent}, journal = {Journal of Physical Chemistry}, volume = {97}, year = {1993}, note = {J Phys Chem-UsKx596Times Cited:37Cited References Count:20}, month = {Apr 15}, pages = {3858-3866}, abstract = {

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

}, keywords = {size}, isbn = {0022-3654}, doi = {Doi 10.1021/J100117a037}, url = {://WOS:A1993KX59600037}, author = {Rosen, M. E. and Rucker, S. P. and Schmidt, C. and Pines, A.} } @article {475, title = {High-Field Cross-Polarization Nmr from Laser-Polarized Xenon to a Polymer Surface}, journal = {Journal of the American Chemical Society}, volume = {115}, year = {1993}, note = {J Am Chem SocLx752Times Cited:77Cited References Count:16}, month = {Sep 8}, pages = {8491-8492}, keywords = {gas}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja00071a086}, url = {://WOS:A1993LX75200086}, author = {Long, H. W. and Gaede, H. C. and Shore, J. and Reven, L. and Bowers, C. R. and Kritzenberger, J. and Pietrass, T. and Pines, A. and Tang, P. and Reimer, J. A.} } @article {474, title = {Spin-Polarized Xe-129 Nmr-Study of a Polymer Surface}, journal = {Journal of Physical Chemistry}, volume = {97}, year = {1993}, note = {J Phys Chem-UsKp603Times Cited:51Cited References Count:48}, month = {Feb 25}, pages = {1649-1655}, abstract = {

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

}, keywords = {temperature}, isbn = {0022-3654}, doi = {Doi 10.1021/J100110a029}, url = {://WOS:A1993KP60300029}, author = {Raftery, D. and Reven, L. and Long, H. and Pines, A. and Tang, P. and Reimer, J. A.} } @article {489, title = {Nmr of Optically Pumped Xenon Thin-Films}, journal = {Chemical Physics Letters}, volume = {191}, year = {1992}, note = {Chem Phys LettHp501Times Cited:25Cited References Count:25}, month = {Apr 10}, pages = {385-390}, abstract = {

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

}, isbn = {0009-2614}, doi = {Doi 10.1016/0009-2614(92)85396-R}, url = {://WOS:A1992HP50100002}, author = {Raftery, D. and Long, H. and Reven, L. and Tang, P. and Pines, A.} } @article {488, title = {Solid-state Al-27 NMR studies of aluminophosphate molecular sieves}, journal = {Solid State Nuclear Magnetic Resonance}, volume = {1}, year = {1992}, note = {Solid State Nucl MagV26hsTimes Cited:12Cited References Count:33}, month = {Nov}, pages = {217-225}, abstract = {Solid-state Al-27 NMR spectra of several aluminophosphate molecular sieves have been recorded with conventional magic-angle spinning (MAS), double-rotation (DOR) and quadrupole nutation with fast MAS. Enhanced resolution was obtained in the quadrupole nutation experiment at certain radiofrequency pulse strengths. This extra resolution can be comparable to that attainable using DOR, and does not introduce spinning sidebands.}, keywords = {double-rotation}, isbn = {0926-2040}, url = {://WOS:000208537300007}, author = {Rocha, J. and Klinowski, J. and Barrie, P. J. and Jelinek, R. and Pines, A.} } @article {501, title = {High-Field Nmr of Adsorbed Xenon Polarized by Laser Pumping}, journal = {Physical Review Letters}, volume = {66}, year = {1991}, note = {Phys Rev LettEv897Times Cited:202Cited References Count:35}, month = {Feb 4}, pages = {584-587}, abstract = {

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

}, keywords = {solids}, isbn = {0031-9007}, doi = {Doi 10.1103/Physrevlett.66.584}, url = {://WOS:A1991EV89700017}, author = {Raftery, D. and Long, H. and Meersmann, T. and Grandinetti, P. J. and Reven, L. and Pines, A.} } @article {510, title = {Measurement of Xenon Distribution Statistics in Na-a Zeolite Cavities}, journal = {Physical Review Letters}, volume = {66}, year = {1991}, note = {Phys Rev LettEv897Times Cited:78Cited References Count:21}, month = {Feb 4}, pages = {580-583}, abstract = {

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

}, keywords = {fluids}, isbn = {0031-9007}, doi = {Doi 10.1103/Physrevlett.66.580}, url = {://WOS:A1991EV89700016}, author = {Chmelka, B. F. and Raftery, D. and Mccormick, A. V. and Demenorval, L. C. and Levine, R. D. and Pines, A.} } @article {511, title = {Nmr-Study of the Distribution of Aromatic-Molecules in Nay Zeolite}, journal = {Journal of Physical Chemistry}, volume = {95}, year = {1991}, note = {J Phys Chem-UsEr473Times Cited:70Cited References Count:64}, month = {Jan 10}, pages = {303-310}, abstract = {

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

}, keywords = {catalysts}, isbn = {0022-3654}, doi = {Doi 10.1021/J100154a056}, url = {://WOS:A1991ER47300056}, author = {Chmelka, B. F. and Pearson, J. G. and Liu, S. B. and Ryoo, R. and Demenorval, L. C. and Pines, A.} } @article {522, title = {2-Dimensional Nmr-Studies of Flexible Molecules in Liquid-Crystals - Orientational Order and Conformational Probabilities of N-Hexane}, journal = {Molecular Physics}, volume = {69}, year = {1990}, note = {Mol PhysCy544Times Cited:38Cited References Count:55}, month = {Mar}, pages = {671-695}, isbn = {0026-8976}, doi = {Doi 10.1080/00268979000100501}, url = {://WOS:A1990CY54400007}, author = {Gochin, M. and Pines, A. and Rosen, M. E. and Rucker, S. P. and Schmidt, C.} } @article {523, title = {Investigations of Adsorbed Organic-Molecules in Na-Y Zeolite by Xe-129 Nmr}, journal = {Journal of Physical Chemistry}, volume = {94}, year = {1990}, note = {J Phys Chem-UsCh532Times Cited:61Cited References Count:26}, month = {Jan 11}, pages = {27-31}, isbn = {0022-3654}, doi = {Doi 10.1021/J100364a006}, url = {://WOS:A1990CH53200006}, author = {Demenorval, L. C. and Raftery, D. and Liu, S. B. and Takegoshi, K. and Ryoo, R. and Pines, A.} } @inbook {555, title = {Calcination-dependence ofplatinum cluster formation in NaY zeolite: A xenon-129 NMR study}, booktitle = {Structure and Reactivity of Surfaces}, year = {1989}, pages = {269-278}, publisher = {Elsevier Science Publishers}, organization = {Elsevier Science Publishers}, address = {Amsterdam}, author = {Chmelka, B.F. and de Menorval, L.C. and Csencsits, R. and Ryoo, R. and Liu, S.B. and Radke, C.J. and Petersen, E.E. and Pines, A.}, editor = {C. Morterra, A. Zecchina, and G. Costa} } @article {563, title = {Iterative Carr-Purcell Trains}, journal = {Journal of Magnetic Resonance}, volume = {77}, year = {1988}, note = {J Magn ResonN4561Times Cited:39Cited References Count:13}, month = {May}, pages = {606-611}, isbn = {0022-2364}, doi = {Doi 10.1016/0022-2364(88)90022-4}, url = {://WOS:A1988N456100022}, author = {Shaka, A. J. and Rucker, S. P. and Pines, A.} } @article {558, title = {Observation of Molecular-Reorientation in Ice by Proton and Deuterium Magnetic-Resonance}, journal = {Journal of the American Chemical Society}, volume = {110}, year = {1988}, note = {J Am Chem SocP7649Times Cited:80Cited References Count:16}, month = {Aug 17}, pages = {5668-5671}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja00225a013}, url = {://WOS:A1988P764900013}, author = {Wittebort, R. J. and Usha, M. G. and Ruben, D. J. and Wemmer, D. E. and Pines, A.} } @article {569, title = {Probing Metal Cluster Formation in Nay Zeolite by Xe-129 Nmr}, journal = {Journal of the American Chemical Society}, volume = {110}, year = {1988}, note = {J Am Chem SocP0739Times Cited:33Cited References Count:18}, month = {Jun 22}, pages = {4465-4467}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja00221a086}, url = {://WOS:A1988P073900086}, author = {Chmelka, B. F. and Ryoo, R. and Liu, S. B. and Demenorval, L. C. and Radke, C. J. and Petersen, E. E. and Pines, A.} } @article {583, title = {Distribution of Hexamethylbenzene in a Zeolite Studied by Xe-129 and Multiple-Quantum Nmr}, journal = {Journal of Physical Chemistry}, volume = {91}, year = {1987}, note = {J Phys Chem-UsL6632Times Cited:63Cited References Count:16}, month = {Dec 31}, pages = {6575-6577}, isbn = {0022-3654}, doi = {Doi 10.1021/J100311a003}, url = {://WOS:A1987L663200003}, author = {Ryoo, R. and Liu, S. B. and Demenorval, L. C. and Takegoshi, K. and Chmelka, B. and Trecoske, M. and Pines, A.} } @article {616, title = {Multiple-Quantum Nmr-Study of Clustering in Hydrogenated Amorphous-Silicon}, journal = {Physical Review Letters}, volume = {56}, year = {1986}, note = {Phys Rev LettA6285Times Cited:157Cited References Count:13}, month = {Mar 31}, pages = {1377-1380}, isbn = {0031-9007}, doi = {Doi 10.1103/Physrevlett.56.1377}, url = {://WOS:A1986A628500016}, author = {Baum, J. and Gleason, K. K. and Pines, A. and Garroway, A. N. and Reimer, J. A.} } @article {649, title = {Nmr-Study of Molecular-Reorientation under Fivefold Symmetry - Solid Permethylferrocene}, journal = {Journal of the American Chemical Society}, volume = {103}, year = {1981}, note = {J Am Chem SocKy444Times Cited:68Cited References Count:21}, pages = {28-33}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja00391a006}, url = {://WOS:A1981KY44400006}, author = {Wemmer, D. E. and Ruben, D. J. and Pines, A.} } @article {664, title = {Viscosity and Temperature-Dependence of the Magnetic Isotope Effect}, journal = {Journal of Chemical Physics}, volume = {73}, year = {1980}, note = {J Chem PhysKx295Times Cited:53Cited References Count:35}, pages = {5493-5499}, isbn = {0021-9606}, doi = {Doi 10.1063/1.440068}, url = {://WOS:A1980KX29500010}, author = {Sterna, L. and Ronis, D. and Wolfe, S. and Pines, A.} } @inbook {682, title = {Double quantum NMR in solids}, booktitle = {Magnetic Resonance in Condensed Matter: Recent developments}, year = {1977}, pages = {127-129}, publisher = {University of Ljubljana Press}, organization = {University of Ljubljana Press}, author = {Pines, A. and Vega, S. and Ruben, D.J. and Shattuck, T.W. and Wemmer, D.}, editor = {Lahajanr, R. Blinc and G.} } @article {686, title = {New Approach to High-Resolution Proton Nmr in Solids - Deuterium Spin Decoupling by Multiple-Quantum Transitions}, journal = {Physical Review Letters}, volume = {36}, year = {1976}, note = {Phys Rev LettBb171Times Cited:105Cited References Count:12}, pages = {110-113}, isbn = {0031-9007}, doi = {Doi 10.1103/Physrevlett.36.110}, url = {://WOS:A1976BB17100014}, author = {Pines, A. and Ruben, D. J. and Vega, S. and Mehring, M.} } @article {690, title = {Qualitative Analysis of Chemisorbed Molecular Species Via C-13 Nmr}, journal = {Surface Science}, volume = {47}, year = {1975}, note = {Surf SciV7219Times Cited:36Cited References Count:22}, pages = {661-665}, isbn = {0039-6028}, doi = {Doi 10.1016/0039-6028(75)90211-3}, url = {://WOS:A1975V721900023}, author = {Chang, J. J. and Pines, A. and Fripiat, J. J. and Resing, H. A.} } @article {694, title = {Molecular Ordering and Even-Odd Effect in a Homologous Series of Nematic Liquid-Crystals}, journal = {Physical Review Letters}, volume = {33}, year = {1974}, note = {Phys Rev LettU3736Times Cited:72Cited References Count:26}, pages = {1002-1005}, isbn = {0031-9007}, doi = {Doi 10.1103/Physrevlett.33.1002}, url = {://WOS:A1974U373600004}, author = {Pines, A. and Ruben, D. J. and Allison, S.} } @article {711, title = {Electrochemical Synthesis of Cis-3,4-Dicarbomethoxycyclobutene}, journal = {Israel Journal of Chemistry}, volume = {11}, year = {1973}, note = {Israel J ChemP7708Times Cited:5Cited References Count:13}, pages = {75-77}, isbn = {0021-2148}, url = {://WOS:A1973P770800010}, author = {Leftin, J. H. and Redpath, D. and Pines, A. and Gilav, E.} } @article {718, title = {Homogeneous and Inhomogeneous Nuclear Spin Echoes in Solids}, journal = {Journal of Magnetic Resonance}, volume = {6}, year = {1972}, note = {J Magn ResonM2264Times Cited:33Cited References Count:32}, pages = {457-\&}, isbn = {1090-7807}, doi = {Doi 10.1016/0022-2364(72)90154-0}, url = {://WOS:A1972M226400001}, author = {Pines, A. and Rhim, W. and Waugh, J. S.} } @article {719, title = {P-31 Chemical Shielding Anisotropy in Solids - Single-Crystal and Powder Studies at 99.4 Mhz}, journal = {Journal of Chemical Physics}, volume = {56}, year = {1972}, note = {J Chem PhysL3043Times Cited:33Cited References Count:21}, pages = {991-\&}, isbn = {0021-9606}, doi = {Doi 10.1063/1.1677259}, url = {://WOS:A1972L304300043}, author = {Gibby, M. G. and Waugh, J. S. and Pines, A. and Rhim, W. K.} } @article {713, title = {Spin Echoes and Loschmidt{\textquoteright}s paradox}, journal = {Journal Pure Applied Chemistry}, volume = {32}, year = {1972}, pages = {317-324}, author = {Waugh, J.S. and Rhim, W.-K. and Pines, A.} } @article {724, title = {C-13 Chemical Shielding Anisotropy in Solids - Cs2 and Caco3}, journal = {Journal of Chemical Physics}, volume = {54}, year = {1971}, note = {J Chem PhysJ6303Times Cited:30Cited References Count:17}, pages = {5438-\&}, isbn = {0021-9606}, doi = {Doi 10.1063/1.1674855}, url = {://WOS:A1971J630300070}, author = {Pines, A. and Rhim, W. K. and Waugh, J. S.} } @article {727, title = {Spin-Decoupling in Resolution of Chemical Shifts in Solids by Pulsed Nmr}, journal = {Journal of Chemical Physics}, volume = {54}, year = {1971}, note = {J Chem PhysJ1849Times Cited:49Cited References Count:9}, pages = {3239-\&}, isbn = {0021-9606}, doi = {Doi 10.1063/1.1675324}, url = {://WOS:A1971J184900070}, author = {Mehring, M. and Pines, A. and Rhim, W. K. and Waugh, J. S.} } @article {723, title = {Time-Reversal Experiments in Dipolar-Coupled Spin Systems}, journal = {Physical Review B}, volume = {3}, year = {1971}, note = {Phys Rev BI5979Times Cited:281Cited References Count:36}, pages = {684-\&}, doi = {Doi 10.1103/Physrevb.3.684}, url = {://WOS:A1971I597900016}, author = {Rhim, W. K. and Pines, A. and Waugh, J. S.} } @article {729, title = {Violation of Spin-Temperature Hypothesis}, journal = {Physical Review Letters}, volume = {25}, year = {1970}, note = {Phys Rev LettG8549Times Cited:140Cited References Count:17}, pages = {218-\&}, isbn = {0031-9007}, doi = {Doi 10.1103/Physrevlett.25.218}, url = {://WOS:A1970G854900007}, author = {Rhim, W. K. and Pines, A. and Waugh, J. S.} } @booklet {734, title = {Hindered Internal Rotation and Dimerization of N,N-Dimethylformamide in Carbon Tetrachloride}, journal = {Journal of the American Chemical Society}, volume = {91}, year = {1969}, note = {J Am Chem SocC9912Times Cited:170Cited References Count:39}, pages = {1585-\&}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja01035a001}, url = {://WOS:A1969C991200001}, author = {Rabinovi, M. and Pines, A.} } @article {735, title = {Association of Dimethylformamide Molecules in Carbon Tetrachloride Solution}, journal = {Journal of the Chemical Society B-Physical Organic}, year = {1968}, note = {J Chem Soc BC0167Times Cited:47Cited References Count:14}, pages = {1110-\&}, doi = {Doi 10.1039/J29680001110}, url = {://WOS:A1968C016700007}, author = {Rabinovi, M. and Pines, A.} } @article {736, title = {A Nuclear Magnetic Resonance Total Line-Shape Treatment of Internal Rotation in Dimethylformamide}, journal = {Tetrahedron Letters}, year = {1968}, note = {Tetrahedron LettB1658Times Cited:26Cited References Count:15}, pages = {3529-\&}, isbn = {0040-4039}, url = {://WOS:A1968B165800021}, author = {Pines, A. and Rabinovi, M.} }