Ionizing Collisions of Fast K Atoms with Oriented Symmetric Top Molecules: Preliminary Results

Abstract

A harpoon-type mechanism has been proposed [1] to explain the angular distribution of the scattering of low-energy K atoms from oriented CF₃I. This proposes that an electron from the K atom is transferred to the CF₃I at long range giving rise to a CF₃I^- ion in a repulsive state. The CF₃I^- then dissociates impulsively with the CF₃ radical and I^- ion separating along the instantaneous direction of the C-I bond and the KI product recoiling with a momentum given by the resultant of the K⁺ and I^- momenta. This predicts that KI will be backward scattered for “heads” orientation (K incident on the I end of the molecule) and forward scattered for “tails” orientation. The model is in good agreement with experiment, and moreover, correctly accounts for the experimental angular distribution resulting from “sideways” oriented molecules.

On leave from the Chemistry Department, University of Canterbury, Christchurch, New Zealand.