Reactive scattering of a supersonic deuterium atom beam: D + Br2, Cf3I, C2F5I, C3F7I

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 fluoroalkyl 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. (author)