Binary collision-induced light scattering by isotropic molecular gases

Abstract

An experiment to measure the two-body collision-induced light scattering spectrum of Ar, CH4, CD4, CF4 and SF6 is described. Contrary to previous studies, the argon spectral intensity is shown to exceed that of the predictions of the first order dipole-induced-dipole model for the pair polarizability anisotropy. It is demonstrated empirically that this intensity can be accounted for by second-order quantum mechanical effects. The spectral profile is analysed in terms of various modifications to the pair polarizability. The main object of this study is to provide a basis for comparison with the molecular spectra described in paper II of this series.