Dissociation in dilute mixtures of shock heated in O2 and HCl in Ar

Abstract

The collision induced dissociation (CID) process in dilute mixtures of shock heated O2Ar and HClAr is investigated. The dissociation is assumed to occur from all vibrational levels. Numerical calculations are presented for the steady state dissociation rate constants at infinite dilution for both the truncated harmonic oscillator (THO) and Morse oscillator (MO) models. The effect of vibration-vibration (V-V) energy transfer processes on the dissociation is also investigated by calculating the steady state rate constants as a function of composition up to 20% of the diatom in these mixtures at 3500 K, 5000 K and 8500 K. The vibration-translation (V-T) energy transfer probabilities are obtained using SSH theory in the case of O2 and Moore’s theory in the case of HCl, and the V-V energy transfer probabilities are obtained using SSH theory in both the cases. The “vibrational bias” parameter λ, characterizing the CID probability, has been varied to fit the experimental data. The study shows that the effect of V-V transitions is dependent on the extent of depletion and the relative magnitudes of the V-V and V-T transition rates. Thus there is no effect on the rate in O2Ar while the rate is enhanced at 3500 K and 5000 K in HClAr mixtures.