Vibrational and rotational relaxation of CDCl3 in nonpolar solvents

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Abstract
Vibrational and reorientational correlation functions and correlation times for the ν1 band of CDCl3 in the pure liquid and in solutions in carbon tetrachloride, n‐hexane, and carbon disulfide have been obtained using spontaneous Raman scattering, and reorientational correlation times have been obtained from deuterium spin relaxation measurements. The concentration dependence of the reorientational correlation times in the CDCl3/CS2 and CDCl3/n‐hexane solutions closely paralleled the solution viscosity, while in CDCl3/CCl4 mixtures, the correlation time exhibited little concentration dependence. These features reflect differences in the anisotropy of the intermolecular potential experienced by the CDCl3 molecules in these solutions. The reorientational correlation functions for the pure liquid exhibited time dependences different from that of the extended rotational diffusion models and a stochastic second‐order memory function model. The temperature dependence of the vibrational relaxation times and vibrational second moments of ν1 in CDCl3 liquid is not consistent with Kubo‐type dephasing models. The vibrational relaxation data indicate that collisional dephasing (Fischer–Lauberau model) is the probable mechanism of relaxation, but do not rule out contributions from energy relaxation via independent binary collisions. In CDCl3/CS2 mixtures, the band frequency and the bandwidth exhibit concentration dependence in accord with microscopic concentration fluctuations in the solution.