%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 NQI Newsletter %D 1994 %T SQUID-NQR of N-14 %A Ziegeweid, M. %A Werner, U. %A Black, B. %A Pines, A. %B NQI Newsletter %V 3 %P 24-25 %G eng %N 1 %! SQUID-NQR of N-14 %0 Journal Article %J Chemical Physics Letters %D 1993 %T Squid-Nqr of N-14 in Amino-Acids and Small Peptides %A Werner, U. %A Black, B. %A Ziegeweid, M. %A Pines, A. %K resonance %X

We present a technique for the study of nuclear quadrupole resonance of N-14 interacting with low electric field gradients as found, for example, in amino acids. A superconducting quantum interference device (SQUID) is used to detect directly small NMR signals via cross relaxation of the N-14 polarization to adjacent proton spins, eliminating the need for field cycling. When one nitrogen quadrupolar transition matches the proton Zeeman splitting, the remaining two quadrupolar transitions can be observed by sweeping a saturating rf field through resonance. In addition, signal enhancement by simultaneous excitation of two nitro n resonances helps to identify connected transitions.

%B Chemical Physics Letters %V 209 %P 17-21 %8 Jun 25 %@ 0009-2614 %G English %U ://WOS:A1993LH24600003 %N 1-2 %M WOS:A1993LH24600003 %! Squid-Nqr of N-14 in Amino-Acids and Small Peptides %R Doi 10.1016/0009-2614(93)87194-8 %0 Journal Article %J Bulletin of Magnetic Resonance %D 1990 %T A suggestion for detecting rotational tunnelling of CD3: Groups by mulitple quantum spectroscopy %A Werner, U. %A Muller-Warmuth, W. %A Pines, A. %B Bulletin of Magnetic Resonance %V 12 %P 9-14 %G eng %N 1/2 %! A suggestion for detecting rotational tunnelling of CD3: Groups by mulitple quantum spectroscopy