From radical–radical association rates to potential-energy parameters: SACM comparison of the reactions H + C7H7⇌ C7H8 and H + CH3⇌ CH4

Abstract

The measurement of radical–radical association rates in the high-pressure limit (as well as the reverse dissociation rates) provides a direct access to properties of the potential-energy surface of the reaction. However, the rate is sensitive only to some average properties of the potential. This article demonstrates the influence of the attractive and the anisotropic part of the potential. The application to the H + benzyl ⇌ toluene reaction system indicates that a variable anisotropy model is required to reproduce the experiments. The treatment uses a simplified SACM approximation which can be formulated in analytical form. The results are compared with an analysis of the H + methyl ⇌ methane reaction system.