An analysis is made of the dynamics of the electronic spectra of complex molecules associated with the nuclear motion, and of its manifestation on exposure of a molecule to high-power optical radiation. A model is proposed for the inhomogeneous broadening dynamics. This describes the random walk of the spectral frequency in the form of a Gauss-Markov random process and allows for the relaxation of the spectra which accompanies an electronic transition. Simple readily interpreted relationships, which describe the influence of nuclear relaxation on the stimulated emission frequency, are obtained.
An experimental investigation was made of the reflection by a nonlinearity from gain saturation in the active medium of a TEA CO 2 laser under degenerate four-wave mixing conditions. A new mechanism of relaxation of the response to such a nonlinearity was identified and processes with submicrosecond and subnanosecond relaxation times were found in CO 2 . The saturation intensities for these processes and the conditions for achieving high reflection intensities as a result of such a mixing were determined.