Depolarization ratios of gas mixtures

Collision-induced scattering is studied in a gas mixture of two kinds of optically isotropic particles. Rayleigh and vibrational Raman collisional depolarization ratios are obtained in the first-order dipole—induced-dipole (DID) approximation, in terms of two-, three-, and four-body correlation contributions. At the low-density limit, Rayleigh and vibrational Raman depolarization ratios due to the unlike-particle pairs are found to be equal and given as a function of the intermolecular pair potential. Experimental data are obtained for Rayleigh and Raman depolarization ratios of the gas mixture argon-tetrafluoromethane at 296 K. The experimental Rayleigh depolarization ratio induced by unlike-particle pair argon-tetrafluoromethane are deduced for the case of binary-collision conditions. It is in good agreement with the value calculated from the DID model using a Lennard-Jones intermolecular potential. However, a comparison between Rayleigh and Raman data shows that all collision-induced integrated intensities for the unlike-particle pair Ar-${\mathrm{CF}}_4$ may not be described only in terms of DID interactions.