Phase-Space Theory of Chemical Kinetics

Abstract

A theory of the cross sections of three‐body gas‐phase reactions which proceed without activation energy is presented. It is based on the hypothesis that the decomposition of a collision complex is governed by the phase space available to each product under conservation of angular momentum and energy. Calculations on model ion—molecule systems show that the cross section is enhanced if the reaction is exothermic, the final reduced mass is large, and the final long‐range attractive forces are large. The theory gives a consistent explanation for the cross sections of the reactions between He⁺ and H₂, and He and H₂⁺ which is in satisfactory agreement with experiment.