摘要 :
Our work this month has been determining the effect of added surface dysprosium(III) ions on the NMR spectra of coal. We have also been examining the effect of this relaxation agent on our model system, an aryl sulfonate silica ge...
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Our work this month has been determining the effect of added surface dysprosium(III) ions on the NMR spectra of coal. We have also been examining the effect of this relaxation agent on our model system, an aryl sulfonate silica gel. To the best of our knowledge, NMR has not previously been. applied to surface studies of coal. It is a powerful technique because line positions and intensities are indicative of geometry, bonding hybridization and population of distinct functionalities as well as local environment effects. The NMR spectrum can be influenced by many factors including dipolar through-space coupling between an unpaired electron spin and the spin of the carbon atom. The unpaired electron can act as a relaxation sink, significantly shortening the spin-lattice relaxation time (T(sub 1)) of the coupled carbon-13 atom. This shortening of the T(sub 1) can broaden the signal to the point where it disappears into the baseline noise. The effective range of interaction is proportional to the inverse sixth power of the separation of the two spins (r(sup (minus)6)). In this system, the effective range is a relatively short distance on the order of 1 nanometer.
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摘要 :
It is shown that the second law of thermodynamics induces uniqueness and continuous dependence upon initial state and supply terms of smooth thermodynamic processes of thermoelastic fluids within the broader class of thermodynamic...
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It is shown that the second law of thermodynamics induces uniqueness and continuous dependence upon initial state and supply terms of smooth thermodynamic processes of thermoelastic fluids within the broader class of thermodynamic processes with shock waves.
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