Depolarized light-scattering in liquid SF6

Abstract

The spectra of depolarized light scattered by liquid SF₆ have been obtained for states along the co-existence curve. They can be decomposed into a broad background and a narrow component. The intensity of the latter amounts to about 80 per cent and 65 per cent of the total depolarized intensity near the critical point and the triple point, respectively, and decreases with increasing density. In a restricted frequency range ⩽-20 cm^-1 its line-shape is roughly a lorentzian with a half width of around 6 cm^-1. This component is explained by the so-called ‘dipole-induced dipole’ effect (DID) and is assumed to reflect the collective motion of a molecule and its neighbours. The background is of rather exponential shape and its intensity is almost constant within experimental uncertainty in the density range studied. It is assumed that this behaviour reflects the increased importance of short-range contributions to the polarizability anisotropy at high densities in addition to the classical DID term.