Master Equation Study and Nonequilibrium Chemical Reactions for Hydrogen Molecule

Abstract

The state-to-state cross sections and rates for collisional transitions of rotational and vibrational states were first calculated by using quasi-classical trajectory calculations for H(2) + H(2) collisions. Accuracy of these calculations was verified by comparing them with the results of quantum mechanical and other quasi-classical trajectory calculations. A system of master equations was constructed for a total of 348 ro-vibrational states with these rate coefficients. Unlike in existing works,the internal states of the colliding particles were assumed to be distributed under a Boltzmann distribution specified by a nonequilibrium temperature. The nonequilibrium temperature was in turn determined from the ro-vibrational energy contents. From the results of the master equation calculation, the relaxation rate of vibrational and rotational modes, rate of relaxation of number densities, the average ro-vibrational energy transferred during dissociation, the quasi-steady state rate coefficients, and two-temperature rate coefficients were derived. The present results are different from those of Sharma ("Rotational Relaxation of Molecular Hydrogen at Moderate Temperatures," Journal of Thermophysics and Heat Transfer, Vol. 8, No. 1, 1994, pp. 35-39) and of Furudate et al. ("Coupled Rotational-Vibrational Relaxation of Molecular Hydrogen at High Temperatures," Journal of Thermophysics and Heat Transfer, Vol. 20, No. 3, 2006, pp. 457-464), and agree closer with existing experimental data.