Temperature dependence of the collision-induced light scattering byCH4gas

The two-body collision-induced light-scattering spectrum of gaseous ${\mathrm{CH}}_4$ was studied as a function of temperature from 295 K to that of the saturated vapor, 130 K. Models to explain both the induced translational and rotational scattering worked well over this wide temperature range. The validity of a fixed-parameter expression for the pair polarizability important to the translational scattering was shown to hold approximately. Values of the dipole-quadrupole and dipole-octopole polarizabilities were consistent with earlier determinations and served to confirm the applicability of the long-range model of the induction mechanism giving the rotational scattering. The contribution of bound dimers to the spectrum was identified and its temperature evolution studied.