Double resonances of parametric susceptibilities in the case of vibrationalrotational transitions in molecules

An analysis is made of the frequency addition processes in the case of a two-frequency double resonance involving vibrational-rotational transitions and their potential applications in nonlinear spectroscopy. A study is made of the influence of the saturation effect and of the frequency detuning from one- and two-photon resonances on the conversion processes and estimates are obtained for a specific molecular gas. It is shown that in the case of two-frequency interaction under double resonance conditions the efficiency of conversion of a probe wave into a wave at the signal frequency increases at least several hundred times, compared with the case of the onefrequency interaction.