THE INFLUENCE OF ROTATIONAL ENERGY ON THE CROSS-SECTION OF DIRECT REACTIONS - COMPARISON OF A SIMPLE-MODEL WITH CLASSICAL TRAJECTORIES

A simple dynamical model which incorporates angular momentum conservation has been developed to account for the rotational-energy dependence of the reaction cross-section in elementary chemical reactions. The model was tested against classical-trajectory calculations for the Na + ICH3 and CH3 + H-2 --> CH4 + H reactions, and it seems to be useful for the diagnosis and parametrization of the rotational-energy dependence of the reaction cross-section. A rationale of this rotational-energy dependence is presented and discussed in terms of the so-called adiabaticity parameter, i.e. the ratio between the collision time and the rotational period of the colliding particles.