Collision-Induced Light Scattering in Gases. I. The Rare Gases: Ar, Kr, and Xe

Gaseous Ar, Kr, and Xe are observed at room temperature to scatter light into a broad frequency band whose intensity varies as the square of the density at low densities. Such scattering is attributed to an incremental polarizability due to the distortion of the electronic distributions of colliding atoms. Studies of the depolarization ratio show that the collision-induced spherical polarizability is negligible with respect to the induced anisotropy. Within experimental error, the (relative) integrated depolarized intensity at low densities and the second virial Kerr coefficient, to which it is directly related, are in agreement. Studies made at wave-number deviations of about 5 - 100 cm^-1 from the laser frequency show that the spectral shape is exponentiallike and the bandwidth is of the order of the duration of collision.