DIRECT DYNAMICS OF F+CCL3BR REACTIVE SCATTERING

Reactive scattering of F atoms with CCl3Br molecules has been studied at an initial translation energy E approximately 38 kJ mol-1, using a supersonic beam of F atoms seeded in He buffer gas, and at E approxima tely 12 kJ mol-1 using Ne buffer gas. At high collision energy the cen tre-of-mass differential cross-section peaks sharply in the forward di rection with much lower intensity in the backward hemisphere. The prod uct translational energy is higher for scattering in the forward direc tion than for scattering in the sideways and backward directions. At l ow collision energy, the differential cross-section favours the forwar d hemisphere, but without any sharp forward peaking, and the product t ranslational energy distribution shows little dependence on scattering angle. The reactive scattering shows good general agreement with the DIPR model for direct reaction dynamics with repulsion in the exit val ley of the potential energy surface. The lack of evidence for a signif icant potential energy well on the surface is attributed to reduced ch arge transfer interaction of the form CCl3Br+F-compared with the alkyl iodide reactions, which exhibit long-lived collision dynamics.