Molecular rotational motions are known to influence both Raman scattering of light and nuclear spin relaxation. Therefore, the application of Raman bandshape analysis and NMR relaxation time measurements to probe molecular dynamics in liquids will provide us with a deeper understanding of the dynamical behavior and structure of molecules in the liquid phase. Presented here are (i) studies of molecular reorientation of acetonitrile in the neat liquid phase and in solution by Raman bandshape analysis and NMR relaxation; (ii) studies of reorientational dynamics and internal rotation in transition metal clusters by NMR relaxation.

Cheung, Wai Ming Edwin. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 107-112). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts also in Chinese.

Nuclear magnetic resonance (NMR) provides a convenient probe for the study of molecular reorientation in liquids because nuclear spin-lattice relaxation times are dependent upon the details of molecular motion. The combined application of Raman and Infrared (IR) lineshape analysis can furnish more complete information to characterize the anisotropic rotation of molecules. Presented here are the studies of NMR relaxation times, together with Raman/IR Mneshape analysis of the solvent and temperature dependence of rotational diffusion in 1,3,5-tribromobenzene and 1,3,5-trifluorobenzene. In these experiments, it was found that the rotational diffusion constants calculated from Perrin's stick model were two to three times smaller than the measured values of D, and D,,. Similarly, rotational diffusion constants predicted by the Hu-Zwanzig slip model were too large by a factor of 2. Application of the newer Hynes-Kapral-Weinberg model furnished rotational diffusion constants that were in reasonable agreement with the experimental results. The vibrational peak frequencies and relaxation times of the isotropic Raman spectra of the υ1 modes of CD2Br2 and CHBr3 were studied in solution. The frequency shifts in non-interactive solvents were explained well on the basis of solution variations in the dispersion energy. In Lewis bases, the displacements were in some, but not all, cases greater than predicted. On the other hand, it was found that the vibrational relaxation times of the C-H/C-D modes decreased dramatically in all Lewis base solvents. Therefore, it was concluded that relaxation times of the υ1 modes, rather than frequency shifts, furnish a more reliable measure of hydrogen bonding interactions of halomethanes in solution.