The two-body depolarized, collision-induced light-scattering spectrum of gaseous methane has been measured and analyzed at five temperatures from 295 to 130 K. This spectrum consists of a low-frequency component, which is due to bound dimers (${\mathrm{CH}}_4$${)}_2$, and an intermediate-frequency, purely translational contribution which is due to collisionally interacting ${\mathrm{CH}}_4$ pairs. (The high-frequency part, the rotational induced spectrum, was analyzed elsewhere and is of no great concern here.) The experimental spectra are compared with line-shape calculations based on a refined, empirical pair polarizability model and the spherical average of the Righini-Maki-Klein’s potential [Chem. Phys. Lett. 80, 301 (1981)]. At all temperatures agreement of measured and computed profiles is observed on an absolute intensity scale.

• Received 25 January 1994

DOI:https://doi.org/10.1103/PhysRevA.50.1172