Raman Bandshapes and Rotational Diffusion of Molecules
ILLINOIS UNIV AT URBANA WILLIAM A NOYES LAB
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It is shown that the shapes of vibrational Raman bands, measured with both parallel and crossed nicols, may serve as a tool for the study of the reorientation of rigid molecules or molecular fragments even if other line- broadening mechanisms are not negligible. The theory, developed for the case of isotropic media including dense gases, liquids, and some molecular solids, holds independently of the shape of the molecules the only requirement is that the studied band must be related to a vibration which is sufficiently localized to the individual molecule molecular fragment. An exhaustive characterization of the reorientation properties of all second-rank molecular quantities is shown to be probably out of the reach of Raman spectroscopy except when the molecule molecular fragment has a high symmetry andor a specific model of the reorientation process is accepted.
- Atomic and Molecular Physics and Spectroscopy