Double infrared–third-harmonic-generation resonance as a method for investigating vibrational energy exchange

A diagnostic method is proposed for the study of kinetic processes. This method is based on the relationship between the power of the third harmonic of a probe beam and the populations of resonant vibrational levels. The results are reported of experiments involving a determination of the rate of the intermolecular V–V' relaxation in CF₃J–CD₄ gas mixtures. It is reported that the rate of relaxation increases on increase in the degree of vibrational excitation of the molecules. The advantages of the double infrared–third-harmonicgeneration resonance method are considered.