Raman scattering from pure liquids. Theory of band profiles

A theory is presented to analyze the Raman scattering from liquids formed by diatomic molecules. This theory is based on the fact that the Hamiltonian of a liquid sample is invariant under the operations of the full $N$-symmetric group. This symmetry entirely determines the structure of the theory; it is applicable for all vibrational-modulation speeds. Moreover, the notion of coherence and incoherence of a light scattering process is examined. One finds that the isotropic Raman process is partially coherent, and the anisotropic Raman scattering is basically an incoherent process.