Gas dynamics studied via gas-phase NMR and solid-state NMR studies of quadrupolar nuclei.

摘要

The research presented in this dissertation follows two main themes. First, gas phase xenon nuclear magnetic resonance (NMR) is used to investigate the dynamics of the xenon atoms inside porous materials. The second part describes some investigations of low amplitude radio frequency on the spin dynamics of solid-state quadrupolar nuclei, specifically I = 5/2 nuclei.; The gas phase NMR chapters first show the line shape of the xenon resonance inside the channels of tris(o-phenylenedioxy)cyclotriphosphazene (TPP) as a function of temperature and concentration. The lines shapes can be explained as an interplay of Xe-Xe and Xe-wall interactions. In addition to the generally anisotropic Xenon line shape in the channels, the transverse relaxation, T₂, is also anisotropic. The fastest relaxing components of the resonance are in channels that are perpendicular to the static magnetic field.; Part two if this dissertation, describes investigations of the spin dynamics of an I = 5/2 nuclei, under low amplitude radio frequency pulses. The goal is to improve the existing techniques of high-resolution solid-state NMR of quadrupolar nuclei. Rotary resonance effects are observed in the coherence transfer efficiencies. The final chapter describes an new algorithm that reduces the number of matrix multiplications required to calculate the grouped propagators that are needed for off period observations. This algorithm, the rational reduction algorithm, is only applicable to time-domain calculations where the density in evolved in time. In most cases, the algorithm provides a substantial speed improvement for the multiplications of the individual subpropagators to generate the grouped propagators. Two different optimization routines are used in the rational reduction algorithm. In essence, the rational reduction algorithm is a form of a lossless compression algorithm. Finally, some code examples for performing rotations as well as the rational reduction algorithm are presented in two Appendices.