Chemical shift imaging in rotating solids by radiofrequency field gradients

A dedicated equipment has been designed for solid state NMR imaging in the spatial direction coinciding with the rotation axis of a 13C CP/MAS probe. It involves a two-turn B1 gradient coil whose plane is perpendicular to that axis and a 1H-13C doubly tuned saddle coil used for normal spectroscopic operations, orthogonal to the latter. The experiment provides a two-dimensional diagram with 13C chemical shift in one dimension whereas the second dimension corresponds to the space variable. Some test experiments demonstrate the validity of this approach. Copyright 1998 Academic Press.

Water-surfactant contact studied by 19F-1H heteronuclear overhauser effect spectroscopy

Intermolecular 19F-1H cross-relaxation is measured using heteronuclear Overhauser effect NMR spectroscopy (HOESY) in the micellar solution of cesium pentadecafluorooctanoate. The results are analyzed in terms of a weak 1H-19F cross-relaxation between the water protons and the fluorines in the fluoroalkyl chain and a strong 19F-19F cross-relaxation within the fluoroalkyl chain. The water-surfactant cross-relaxation indicates a water approach to the first CF2 segment in the order of 2.0 A and a short (<

Self-Diffusion Measurements by Carbon-13 NMR Using Radiofrequency Field Gradients

This paper demonstrates the feasibility of self-diffusion measurements by radiofrequency field gradients with equipment tuned to the carbon-13 resonance frequency (i.e., 50 MHz for a field of 4.7 T). For the first time, self-diffusion coefficients of carbon disulfide and carbon tetrachloride are measured by NMR. The agreement with results from tracer methods is excellent. Copyright 1998 Academic Press. Copyright 1998 Academic Press