Molecular beam study of the K + CF3I reaction: Detailed differential reactive cross section and energy disposal

Abstract

The reaction of a velocity-selected K beam with a crossed beam of CF3I (from a thermal capillary-array source) has been studied by the velocity-analysis technique. The observed (laboratory) KI product flux (velocity-angle) contour map, obtained at an average incident relative kinetic energy of 2.9 kcal/mole, has been transformed to yield the center-of-mass (c.m.) detailed differential reaction cross section. The c.m. cross section is ``backward'' peaked, but there is a substantial reactive contribution in the forward hemisphere as well. The average energy released into translational recoil of the products is only 8.5 kcal/mole, so that some 70% of the total available energy is partitioned into internal degrees of freedom of the products (cf. only 40% for the analogous reaction of K + CH3I). The present results are interpreted as weighted, orientation-averaged results of Brooks' dual-mode mechanism for the K + CF3I reaction.