Monte Carlo Calculations. III. A General Study of Bimolecular Exchange Reactions

Abstract

About 10 000 planar trajectories were computed for the reaction A+BC→AB+C. Principal variables were the reactant masses, the type of interaction potential, and the exothermicity. The activation energy was assumed negligible. The results consist of distributions of product emission angle and vibrational and rotational energy. For the simplified interaction potentials used, the following generalizations hold: a normal reaction is one in which AB is most likely to recoil backward along the approach line of A; the energy of reaction is predominantly converted to internal excitation of the product AB; and the final rotation of AB absorbs as large a fraction of the initial orbital angular momentum as is consistent with the reaction energy. If the moment of inertia of AB is too small to allow this fraction to be close to unity, unusual distributions of emission angle and rotational excitation occur. Independently, lowered values of the internal energy of AB are observed if A is much less massive than either B or C, or if the interaction potential is not of the type involving much reactant attraction and little product repulsion. Tentative mechanical explanations of these phenomena are presented.