%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 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 Journal of Chemical Physics %D 2002 %T Theoretical investigations of I=5/2 quadrupolar spin dynamics in the sudden-passage regime %A Walls, J. D. %A Lim, K. H. %A Logan, J. W. %A Urban, J. T. %A Jerschow, A. %A Pines, A. %K SPECTROSCOPY %X

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

%B Journal of Chemical Physics %V 117 %P 518-532 %8 Jul 8 %@ 0021-9606 %G English %U ://WOS:000176424800003 %N 2 %M WOS:000176424800003 %! Theoretical investigations of I=5/2 quadrupolar spin dynamics in the sudden-passage regime %R Doi 10.1063/1.1483256 %0 Journal Article %J Journal of the American Chemical Society %D 1999 %T Study of xenon binding in cryptophane-A using laser-induced NMR polarization enhancement %A Luhmer, M. %A Goodson, B. M. %A Song, Y. Q. %A Laws, D. D. %A Kaiser, L. %A Cyrier, M. C. %A Pines, A. %K SPECTROSCOPY %X

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

%B Journal of the American Chemical Society %V 121 %P 3502-3512 %8 Apr 14 %@ 0002-7863 %G English %U ://WOS:000079884800033 %N 14 %M WOS:000079884800033 %! Study of xenon binding in cryptophane-A using laser-induced NMR polarization enhancement %R Doi 10.1021/Ja9841916 %0 Journal Article %J Chemical Physics Letters %D 1998 %T NMR spectra with peaks at the principal values of the chemical shielding tensor %A de Swiet, T. M. %A Tomaselli, M. %A Pines, A. %K SPECTROSCOPY %X

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

%B Chemical Physics Letters %V 285 %P 59-63 %8 Mar 13 %@ 0009-2614 %G English %U ://WOS:000072889100010 %N 1-2 %M WOS:000072889100010 %! NMR spectra with peaks at the principal values of the chemical shielding tensor %R Doi 10.1016/S0009-2614(97)01478-4