Kinetics of Nonequilibrium Gas Phase Reactions Induced by Vibrational Multiple-Photon IR Laser Excitation of Molecules

Abstract

A simple theoretical model for the qualitative description of the kinetics of the unimolecular decay in the pulsed IR laser field with strong deviation from thermal equilibrium is developed. The nonequilibrium character of the reaction is introduced by means of a special parameter of “truncation” of vibrational energy distribution function, which takes into account depletion of the distribution function due to the dissociation. The derived self-consistent system of differential equations describes the three dissociation regimes. Besides, the apparent cases of collisionless (short duration of laser pulse τp) and equilibrium (long τp) reactions, the intermediate collisional-nonequilibrium dissociation is revealed. The contribution of postpulse reaction has proved considerable in case of both long and short pulses. For the case of a successive dissociation the possibility of synthesis of labile products which cannot be produced at thermal initiation is established.