Abstract: | a quasiclassical trajectory study has been carried out to investigate the dynamics of collisions between Br + HCl (1 υ′ 4) and Br + DCl (υ′ = 2,3). For HCl (υ′ 2) and DCl (υ′ = 3), the endoergic reaction producing Cl + HBr occurs readily, and at approximately the same rate as vibrational deactivation in non-reactive collisions. For HCl(υ′ = 2) and DCl(υ′ = 3), where the initial vibrational energies are similar to |ΔE0 for the reaction, the rates of both reactive and inelastic processes are quite strongly temperature dependent but the ratio of reactive to inelastic encounters is not a strong function of T. Comparison of the calculated results for Br + HCl(υ′ = 1) with experimentally determined rates strongly suggests that, at least at low temperatures, removal of HCl(υ′ = 1) by Br atoms occurs predominantly via electronically non-adiabatic vibrational relaxation. |