Collision-induced light scattering of hydrogen gas at low density

The room-temperature, binary, collision-induced, translational, and rotational spectra of molecular hydrogen are reported. The translational pair spectrum is separated into completely depolarized and polarized components; both are analyzed with quantum line-shape calculations based on the isotropic potential approximation and the dipole-induced-dipole (DID) model for the pair polarizability. A small overlap correction to the DID anisotropy yields a computed line shape that agrees with the observed depolarized, collision-induced spectrum. A substantial overlap correction to the DID trace is needed to produce a line shape consistent with the measurement of the collision-induced trace spectrum. Additionally, this modified DID trace reproduces the experimental data on the second dielectric virial coefficient.