Rayleigh–Raman Depolarization of Laser Light Scattered by Gases

Abstract

The polarization of the fine structure of the Rayleigh line for light scattered by simple gas molecules is examined. New and simple relations are reported between the depolarization factor of the total line (including rotational Raman lines) and the depolarization factor of the unshifted central component. A new high-resolution apparatus for light scattering measurements in gases with photon-counting electronics and a high-power argon-ion laser light source is described. New measurements of the depolarization factor of the total line are reported for H2, N2, O2, CO2, CO, and N2O. High-resolution measurements of the depolarization factor of the central component are also reported for these gases and a critical comparison is made between experiment and classical light scattering theory. In the case of H2 a comparison with recent quantum mechanical calculations is also included.