Stimulated Raman scattering and generation of infrared radiation by rotational transitions

A theory is given of the stimulated Raman scattering involving rotational transitions when the alternative forbiddenness is lifted. The induced dipole moment of the transition is expressed in terms of the scattering tensor which includes a large nuclear contribution. It is shown that the application of a static electric field at right angles to the direction of propagation of the pump wave can produce infrared radiation of frequency equal to the rotational transition responsible for the stimulated Raman scattering. Various special cases are analyzed, and the optimal conditions for the generation of infrared radiation are determined.