NMR studies of guest dynamics in clathrate hydrates: spherical tops SF6, SeF6 and CH4 in structure ll hydrate

Article Abstract:

Spin-lattice relaxation time measurements, obtained between 2 and ~150 K, are presented for (super 19)F in two structure II clathrate hydrates, SF6.17D2O and SeF6.17D2O, as well as for (super 1)H in a double structure II deuteriohydrate of methane and tetrahydrofuran-d(sub 8). In the case of heavy spherical top molecules both the spectral line narrowing region and the spin-lattice relaxation time results can be analyzed in terms of a common classical model for guest reorientation.

Chemistry, Analytic, Analytical chemistry, Clathrate compounds, Hydrates, Structure

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Hydrate kinetics study in the presence of nonaqueous liquid by nuclear magnetic resonance spectroscopy and imaging

Article Abstract:

Nuclear magnetic resonance (NMR) spectroscopy and imaging (MRI) are used to study the dynamics of methane hydrate growth and decomposition. The results have shown that the major portion of hydrate decomposes very quickly under atmospheric conditions and the faster kinetics during hydrate re-formation is explained by the residual methane in hydrate phase and dissolved in nonaqueous liquid (NAL) phase.

Analysis, Dynamics, Dynamics (Mechanics), Mechanical properties

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[super 39]K NMR of solid potassium salts at 21 T: Effect of quadrupolar and chemical shift tensors

Article Abstract:

[super 39]K Solid State NMR spectra (static and magic angle spinning (MAS)) on a set of potassium salts measured at 21.14 T have indicated that the chemical shift range for [K.sup.+] ions in diamagnetic salts is over 100 ppm. The analysis of static and MAS spectra has helped in obtaining the chemical shift and quadrupole coupling tensor components as well as their relative orientations.

Models, Spectra, Potassium salts

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