Angular Time-Correlation Functions from Spectra for Some Molecular Liquids

Abstract

Depolarized Rayleigh wing scattering data are reported for liquid chloroform, methyl iodide and methylene chloride. The calculation of orientation correlation functions from these results and from infrared vibration‐rotation bands is discussed. Fourier transforms of the infrared bands are corrected for shape changes due to variable refractive index, isotope splitting and hot bands. The resulting correlation functions are primarily a measure of orientational and collision‐induced changes in polarizability or dipole moment. It is argued that the collision‐induced contributions are important only at short times. The long‐time behavior of the correlation functions is then compared with several models for molecular reorientation in liquids, and it is concluded that the motion of these molecules is probably best characterized by models involving random walks in angular momentum space.