Third body efficiencies for collision-induced dissociation of diatomics. Rate coefficients for H+H2→3H

Abstract

Fixed-energy cross sections, thermal-translation rate constants, energies of activation, opacity functions, and probabilities of reaction as functions of initial relative orientation angle are presented for the reaction H+H2(v, j)→3H on the lowest-energy potential surface for selected initial vibrational-rotational states (v, j) of H2. In agreement with the experimental result for steady dissociation of a thermal mixture of initial states, the collision-induced dissociation process for these state-selected processes is found to be considerably enhanced for H as collision partner as compared to Ar as collision partner. We find that the cross sections for collision-induced dissociation are strongly increasing functions of initial internal energy and initial vibrational quantum number. The general trend at 4500 K is that the rate constants increase more rapidly than the equilibrium populations decreases as we increase v. The activation energies for complete dissociation are larger than the fixed-state binding energies by 0.2–1.1 eV.