DYNAMICS OF LINEAR EXCHANGE-REACTIONS - QUASI-CLASSICAL MODEL OF HIGH-ENERGY VIBRATIONAL INVERSION

The dynamics of exothermic exchange reactions in natural reaction coordinates (NRC) is investigated analytically. Such a study is possible because (1) there is a small parameter in several chemical systems, i.e., the product of the curvature of the reaction path and the classical amplitude of transversal vibrations, and (2) the motion along the reaction coordinate may be considered quasi-classically. The quasi-classical equations of motion are derived, which have an exact solution. The transition probabilities between vibrational levels are investigated in detail. The quasi-classical analytic distributions are in satisfactory agreement with the numerical results of quantum calculations made for model potential surfaces. The quasi-classical model is shown to fit for real reaction systems with mass ratio L + HH (L is light atom, and H is heavy atom). The main factors which determine the vibrational distribution of products for these reactions are the curvature of the reaction path and the number of open channels at the point of maximum curvature. © 1979.