Reactive scattering of a supersonic deuterium atom beam : D+Br₂, CF₃I, C₂F₅I, C₃F₇I

Abstract

Reactive scattering of D atoms with Br₂, CF₃I, C₂F₅I and C₃F₇I molecules has been studied at an initial translational energy E = 5·3 kJ mol^-1 using a supersonic beam of D atoms seeded in He. Deuterium halide product is scattered in the backward direction with respect to the incident D atoms, with substantial energy disposed into product translation in all cases. The fraction of the total available energy which is disposed into product translation, is greater for the fluoralkyl iodides than for Br₂ and decreases slightly along the series CF₃I, C₂F₅I, C₃F₇I. These results demonstrate that the reaction of D atoms with fluoroalkyl iodides occurs only in collisions at small impact parameters with strong repulsion between the reaction products. The potential energy surfaces for the reactions of the fluoroalkyl iodides are similar to that for the D + Br₂ reaction but involve the release of a still greater proportion of the reaction exoergicity in the exit valley of the surface. Only a small fraction, if any, of the product repulsion is transferred to internal excitation of the product fluoroalkyl radical.