Temperature Dependence of the Rate of Termolecular Atomic Recombinations

Abstract

The rate coefficient for the gas-phase recombination of atoms or free radicals in the presence of third-body molecules is calculated, based upon the radical—molecule complex mechanism. The rate coefficient, kr, is given by kr=Az24/3F2[1,1;(7/4),(9/4);z], z=εL/kT, where A is a constant factor depending on the molecular constants, εL is the energy depth of the Lennard-Jones (12–6) potential between the reactive atom and the third body, k is the Boltzmann constant, T is the absolute temperature, and 2F2(z) is a generalized hypergeometric function. The experimental temperature dependence of iodine atom recombination in the presence of argon atoms is accurately described by the theoretical expression with εL/k=700, A = 5.4×108 liters2 mole−2·sec−1.