The spectral profile of the collision-induced translational light scattering by gaseous CH4. Determination of the pair polarizability anisotropy

The two-body purely translational, collision-induced light scattering spectra of CH4-CH4, CH4-Ar, and CH4-Xe at 295 K are deduced by subtraction of the collision-induced rotational Raman scattering component from the total spectrum. For CH4-CH4, the zeroth moments of the total and purely translational spectrum are 205·4 ± 14 Å9 and 203·8 ± 14 Å9 respectively. The CH4-CH4 translational moments are used to evaluate the parameters in an expression for the pair polarizability anisotropy. Although some ambiguity exists, a model is thus obtained for the extra-DID contributions which is consistent with the inert gas case.