Vibrational Kinetics, Dissociation, and Ionization of Diatomic Molecules Under Nonequilibrium Conditions

Abstract

This chapter deals with the study of nonequilibrium vibrational distributions created by the so-called vibration-vibration (V-V) up-pumping mechanism [2.1] (or Treanor’s mechanism) and with the effects of such a mechanism on chemical reactions of diatomic molecules. Treanor’s mechanism is responsible for the overpopulation of the vibrational distribution of a diatomic molecule under physical conditions characterized by large vibrational temperatures [θ₁ = E₁₀/k ln(N₀/N₁)] and small transiational ones (T_g). (E₁₀ is the energy difference between level 1 and level 0, N₁ and N₂ being the corresponding population densities; k is Boltzmann’s constant.) Indeed, in this case V-V energy exchanges are more effective than vibration-translation (V-T) ones thus creating a quasi-stationary vibrational distribution made up of a Treanor’s distribution for the low-lying vibrational levels, a plateau, and a tail. The extension of this plateau depends on the effectiveness of V-V rates in overcoming the V-T ones [2.2–5].