Cascade mechanism of the excitation of molecular vibrations by resonant laser radiation

A theoretical analysis is made of the vibrational kinetics of molecules under nonequilibrium conditions of the cascade excitation of molecules by resonant laser radiation. The exact solutions of the kinetic equation are obtained in the harmonic oscillator model. An expression is derived for the time dependence of the average vibrational energy accumulated in a specific vibrational mode. The analysis shows that the cascade mechanism has the following advantages: It provides means for an effective control of the rate of excitation of the molecular vibrations and it increases the average energy stored in the vibrational modes. Two methods for combined pumping of a specific vibrational mode are suggested: One is the combined action of a discharge and laser radiation and the other is a combined chemical and laser pumping.