Studies of nonlinear phenomena - I. Theory of the hyper Raman effect

A detailed theoretical treatment of the hyper Raman effect is presented. Using the density matrix treatment we derive general formulae which give information on the frequencies of the scattered radiation, the scattering mechanism and resonance processes. A hyperpolarizability theory analogous to the Placzek polarizability theory is developed and the conditions under which it is valid are established. The enhancement of intensity of hyper Raman scattering through resonance processes is discussed.