Stimulated molecular scattering of light in gases at different pressures

The Boltzmann transport equation method and the Bhatnager-Gross-Krook relaxation representation of the collision integral are used in developing a theory of stimulated molecular scattering (STMS) in polyatomic gases at various pressures. The frequency dependences of the backward STMS and the relaxation time of the effect are calculated for various pressures ranging from a collisionless gas to hydrodynamic conditions. It is shown that the central frequency peak in the STMS spectrum is present, in contrast to the spontaneous effect, only under hydrodynamic conditions. The experimental results are given for the backward STMS in nitrogen in the intermediate range of pressures 1–3 atm.