Depolarization of Rayleigh and non-linear (multi-harmonic) light scattering by molecular systems with electronic degeneracy

The depolarization of Rayleigh and hyper-Rayleigh (second and third harmonic) light scattering by liquid or gas phase molecules in orbitally degenerate states is investigated. It is shown that the degeneracy-induced contribution to the anisotropy of the linear and non-linear polarizabilities results in unusual depolarization ratios, the values of which, taking into account the rotational diffusion, are dependent on the frequency of the scattered light. By means of group-theoretical methods the types of orbital degeneracy for molecules of different symmetries, for which the above anomalous light scattering is possible, are elucidated and by way of example some concrete molecules are discussed.