A master equation study of vibration-dissociation coupling in shock-heated oxygen molecules

The vibration-dissociation coupling phenomena in shock-heated oxygen molecules highly dilute in an argon heat-bath have been studied numerically. State-to-state transition rate coefficients were evaluated by using relatively simple models developed through the information theoretical approach. The master equation was solved by numerical integration to obtain time-resolved vibrational population distributions. The results of the master equation analysis are compared with those obtained by using a widely-used phenomenological vibration-dissociation coupling model. The results show that during the relaxation process the depletion of high-lying vibrational energy levels is severe and significantly affects bulk properties related to dissociation and that the phenomenological model can reproduce qualitatively the bulk relaxation process found in the master equation analysis. Received 26 June 2001 / Accepted 3 December 2002 Published online 4 February 2003