Cascade mechanism of the excitation of molecular vibrations by resonant laser radiation. Multicomponent media

A theoretical analysis is made of the vibrational kinetics in multicomponent gaseous media under nonequilibrium conditions of the cascade excitation by resonant laser radiation. The harmonic oscillator model is used to derive the exact solutions of the kinetic equations. It is shown that all the components of the distribution function retain their Boltzmann form if initially the system is in equilibrium. A system of equations for the vibrational energies is solved. The solutions are obtained for different rates of the vibration-translational relaxation in both modes of a two-component medium. A study is made of the steady-state conditions in a binary mixture. The analysis shows that the neglect of the vibration-vibrational exchange between different modes in polyatomic molecules may result in considerable deviations from the real kinetics in the whole system.