Reactive Scattering of OD Radicals with ICl and Br2 Molecules at Initial Translational Energy E ∼ 90 kJ mol-1

Abstract

Reactive scattering of OD radicals with ICl and Br2 molecules has been studied at an initial translational energy E ∼ 90 kJ mol-1 using a supersonic beam of OD radicals seeded in He buffer gas generated from a high-temperature radio frequency discharge source. The center-of-mass angular distribution of DOI scattering from OD + ICl shows sharp forward and backward peaking with the relative intensity of the backward peak being lower by a factor ∼0.6 ± 0.1. The DOBr scattering from OD + Br2 shows broader peaking in the forward direction declining to a lower intensity ∼0.8 ± 0.2 in the backward direction. In both cases the product translational energy distributions peak at low energy with a tail extending out to higher energy. Comparison with the predictions of phase space theory indicates that the OD + ICl reaction proceeds via a DOICl collision complex with a lifetime of approximately one rotational period, while the OD + Br2 reaction shows evidence for the migration of the OD radical between the Br atoms of a DOBrBr complex. The DOICl complex corresponds to a significant well of depth E0 ∼ 80 kJ mol-1 on the potential energy surface for the OD + ICl reaction while the potential energy surface for the OD + Br2 reaction also supports a shallow minimum.