%0 Journal Article %J Journal of Physical Chemistry %D 1995 %T Solid-State O-17 Magic-Angle and Dynamic-Angle Spinning Nmr-Study of the Sio2 Polymorph Coesite %A Grandinetti, P. J. %A Baltisberger, J. H. %A Farnan, I. %A Stebbins, J. F. %A Werner, U. %A Pines, A. %K oxygen %X

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

%B Journal of Physical Chemistry %V 99 %P 12341-12348 %8 Aug 10 %@ 0022-3654 %G English %U ://WOS:A1995RN70600045 %N 32 %M WOS:A1995RN70600045 %! Solid-State O-17 Magic-Angle and Dynamic-Angle Spinning Nmr-Study of the Sio2 Polymorph Coesite %R Doi 10.1021/J100032a045 %0 Journal Article %J Molecular Physics %D 1994 %T Cross-Polarization Dynamic-Angle Spinning Nuclear-Magnetic-Resonance of Quadrupolar Nuclei %A Baltisberger, J. H. %A Gann, S. L. %A Grandinetti, P. J. %A Pines, A. %K probe %X

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

%B Molecular Physics %V 81 %P 1109-1124 %8 Apr 10 %@ 0026-8976 %G English %U ://WOS:A1994NE62800007 %N 5 %M WOS:A1994NE62800007 %! Cross-Polarization Dynamic-Angle Spinning Nuclear-Magnetic-Resonance of Quadrupolar Nuclei %R Doi 10.1080/00268979400100741 %0 Journal Article %J Journal of Physical Chemistry %D 1994 %T Measurement of Internuclear Distances by Switched Angle Spinning Nmr %A Kolbert, A. C. %A Grandinetti, P. J. %A Baldwin, M. %A Prusiner, S. B. %A Pines, A. %K protein %X

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

%B Journal of Physical Chemistry %V 98 %P 7936-7938 %8 Aug 18 %@ 0022-3654 %G English %U ://WOS:A1994PC61900003 %N 33 %M WOS:A1994PC61900003 %! Measurement of Internuclear Distances by Switched Angle Spinning Nmr %R Doi 10.1021/J100084a003 %0 Journal Article %J Physical Review A %D 1994 %T Multiple-Pulse Nuclear-Magnetic-Resonance of Optically Pumped Xenon in a Low Magnetic-Field %A Raftery, D. %A Long, H. W. %A Shykind, D. %A Grandinetti, P. J. %A Pines, A. %K ne-21 %X

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.

%B Physical Review A %V 50 %P 567-574 %8 Jul %@ 1050-2947 %G English %U ://WOS:A1994NX00100070 %N 1 %M WOS:A1994NX00100070 %! Multiple-Pulse Nuclear-Magnetic-Resonance of Optically Pumped Xenon in a Low Magnetic-Field %R Doi 10.1103/Physreva.50.567 %0 Journal Article %J Journal of Magnetic Resonance Series A %D 1993 %T Pure-Absorption-Mode Lineshapes and Sensitivity in 2-Dimensional Dynamic-Angle Spinning Nmr %A Grandinetti, P. J. %A Baltisberger, J. H. %A Llor, A. %A Lee, Y. K. %A Werner, U. %A Eastman, M. A. %A Pines, A. %K nuclei %B Journal of Magnetic Resonance Series A %V 103 %P 72-81 %8 Jun 1 %@ 1064-1858 %G English %U ://WOS:A1993LJ62500010 %N 1 %M WOS:A1993LJ62500010 %! Pure-Absorption-Mode Lineshapes and Sensitivity in 2-Dimensional Dynamic-Angle Spinning Nmr %R Doi 10.1006/Jmra.1993.1132 %0 Journal Article %J Journal of Magnetic Resonance Series A %D 1993 %T Side-Band Patterns in Dynamic-Angle-Spinning Nmr %A Grandinetti, P. J. %A Lee, Y. K. %A Baltisberger, J. H. %A Sun, B. Q. %A Pines, A. %K samples %B Journal of Magnetic Resonance Series A %V 102 %P 195-204 %8 Apr %@ 1064-1858 %G English %U ://WOS:A1993KZ48000011 %N 2 %M WOS:A1993KZ48000011 %! Side-Band Patterns in Dynamic-Angle-Spinning Nmr %R Doi 10.1006/Jmra.1993.1091 %0 Journal Article %J Israel Journal of Chemistry %D 1992 %T Correlation of Isotropic and Anisotropic Chemical-Shifts in Solids by 2-Dimensional Variable-Angle-Spinning Nmr %A Frydman, L. %A Chingas, G. C. %A Lee, Y. K. %A Grandinetti, P. J. %A Eastman, M. A. %A Barrall, G. A. %A Pines, A. %K magic-angle %X

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

%B Israel Journal of Chemistry %V 32 %P 161-164 %@ 0021-2148 %G English %U ://WOS:A1992KT51700005 %N 2-3 %M WOS:A1992KT51700005 %! Correlation of Isotropic and Anisotropic Chemical-Shifts in Solids by 2-Dimensional Variable-Angle-Spinning Nmr %0 Journal Article %J Journal of Magnetic Resonance %D 1992 %T Double-Tuned Hopping-Coil Probe for Dynamic-Angle-Spinning Nmr %A Eastman, M. A. %A Grandinetti, P. J. %A Lee, Y. K. %A Pines, A. %K axis %B Journal of Magnetic Resonance %V 98 %P 333-341 %8 Jun 15 %@ 0022-2364 %G English %U ://WOS:A1992HZ62300008 %N 2 %M WOS:A1992HZ62300008 %! Double-Tuned Hopping-Coil Probe for Dynamic-Angle-Spinning Nmr %R Doi 10.1016/0022-2364(92)90136-U %0 Journal Article %J Nature %D 1992 %T Quantification of the Disorder in Network-Modified Silicate-Glasses %A Farnan, I. %A Grandinetti, P. J. %A Baltisberger, J. H. %A Stebbins, J. F. %A Werner, U. %A Eastman, M. A. %A Pines, A. %K time %X

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

%B Nature %V 358 %P 31-35 %8 Jul 2 %@ 0028-0836 %G English %U ://WOS:A1992JB34100043 %N 6381 %M WOS:A1992JB34100043 %! Quantification of the Disorder in Network-Modified Silicate-Glasses %R Doi 10.1038/358031a0 %0 Journal Article %J Journal of Chemical Physics %D 1992 %T Variable-Angle Correlation Spectroscopy in Solid-State Nuclear-Magnetic-Resonance %A Frydman, L. %A Chingas, G. C. %A Lee, Y. K. %A Grandinetti, P. J. %A Eastman, M. A. %A Barrall, G. A. %A Pines, A. %K axis %X

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

%B Journal of Chemical Physics %V 97 %P 4800-4808 %8 Oct 1 %@ 0021-9606 %G English %U ://WOS:A1992JR33800022 %N 7 %M WOS:A1992JR33800022 %! Variable-Angle Correlation Spectroscopy in Solid-State Nuclear-Magnetic-Resonance %R Doi 10.1063/1.463860 %0 Journal Article %J Physical Review Letters %D 1991 %T High-Field Nmr of Adsorbed Xenon Polarized by Laser Pumping %A Raftery, D. %A Long, H. %A Meersmann, T. %A Grandinetti, P. J. %A Reven, L. %A Pines, A. %K solids %X

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

%B Physical Review Letters %V 66 %P 584-587 %8 Feb 4 %@ 0031-9007 %G English %U ://WOS:A1991EV89700017 %N 5 %M WOS:A1991EV89700017 %! High-Field Nmr of Adsorbed Xenon Polarized by Laser Pumping %R Doi 10.1103/Physrevlett.66.584 %0 Journal Article %J Journal of the American Chemical Society %D 1991 %T Study of the Aluminophosphates Alpo4-21 and Alpo4-25 by Al-27 Double-Rotation Nmr %A Jelinek, R. %A Chmelka, B. F. %A Wu, Y. %A Grandinetti, P. J. %A Pines, A. %A Barrie, P. J. %A Klinowski, J. %K nuclei %X

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

%B Journal of the American Chemical Society %V 113 %P 4097-4101 %8 May 22 %@ 0002-7863 %G English %U ://WOS:A1991FN00500007 %N 11 %M WOS:A1991FN00500007 %! Study of the Aluminophosphates Alpo4-21 and Alpo4-25 by Al-27 Double-Rotation Nmr %R Doi 10.1021/Ja00011a007