Laser fluorescence and double resonance studies have been made in polyatomic molecules. These experiments monitor the flow of energy between the various degrees of freedom in systems such as CH3F, C2H4, and SF6 as well as mixtures of these molecules with rare gases. In general the rate of equilibration of the vibrational modes among themselves is typically 100-1000 times faster than the rate of equilibration of the vibrational degrees of freedom with the translational and rotational degrees of freedom. For CH3F where the most data is available, a partial vibrational energy transfer map has been developed which provides insight into the paths by which the vibrational modes of this molecule come into equilibrium with each other. Such maps are extremely useful in predicting possible new laser transitions and in the development of laser infrared photochemistry. (Modified author abstract).

Emphasis is placed on the analysis of translational, rotational, vibrational and electronically excited state kinetics, coupled to the electron Boltzmann equation.

The set of master rate equations for the vibrational relaxation of mixtures of anharmonic diatomic gases in supersonic nozzle expansions is integrated numerically. Large deviations from a Boltzmann distribution of vibrational state population are predicted, particularly when vibrational energy is exchanged between two near-resonant diatomic species. Radiative gain coefficients for nonequilibrium vibration-rotation transitions are also computed and positive gains, sufficient to support laser oscillations, are predicted for CO-N2 and CO-N,-Ar admixtures.