Intensity, angular distribution and polarization of spontaneous molecular light scattering

Light scattering theories are outlined for single systems such as free atoms and molecules. To a fair approximation the results apply to gases. The effect of molecular interactions within liquid and crystals on the light scattering phenomenon is shown on the basis of empirical data. The generally accepted quantum mechanical and classic theory of the spontaneous molecular light scattering and the spectral theory of Rayleigh and Raman scattering are treated. The scattering cross sections, which characterize the light scattering by single particles, the intensity of light scattered by a large number of molecules, the angular distribution, and the degree of depolarization of the scattered light are given as functions of polarization state of the incident light and the direction of observation. In order to confirm the theoretical statements and to allow a numerical treatment of the given equations the experimental results of light scattering analysis are presented. Since the specific vibration and rotation constants, the degree of depolarization, and the refractive indices are known for many gases, the frequencies, the intensity distribution, the polarization state, and the angular distribution of Rayleigh and Raman scattering can be calculated.