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 E 0 ∼ 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.

Dynamics of the OH + Cl2 → HOCl + Cl Reaction: Ab Initio Investigation and Quasiclassical Trajectory Calculations of Reaction Selectivity

“…Consequently, the title reaction represents a nice system to test the role of the nonbreaking OH bond in the dynamics of another diatom−diatom reaction. From the mechanistic point of view the experimental kinetic studies were consistent with the assumption that the reaction proceeds through the formation of a short-lived collision complex in analogy with the dynamical behavior observed for OD + ICl and OD, OH + Br 2 reactions. , …”

“…Several recent experimental and theoretical studies have produced interesting details concerning the dynamics and kinetics of various gas-phase elementary four-atom reactions. − An important class of such systems are the reactions of hydroxyl radical with halogen and interhalogen molecules which have been well characterized experimentally − but have received much less attention concerning their dynamical investigation.…”

Chemical reaction dynamics with molecular beams

“…Very recent CMB studies of CN reactions with unsaturated hydrocarbons and of polyatomic radical (C 2 D, C 3 H 3 , C 6 H 5 ) reactions will also be noted. The reactions OD + ICl and OH + Br 2 have also been studied in recent years (Mohr et al 1997).…”

CROSSED-BEAM STUDIES OF REACTION DYNAMICS

“…The late Roger Grice's group in Manchester carried out a great deal of work on a variety of F, Cl, and O( 3 P) reactions (217)(218)(219)(220)(221), as well as some studies of radical reactions such as CH 3 + I 2 (185) and OD + Br 2 (222). A new CMB apparatus has been built at Cornell, and studies of transition metal reaction dynamics have been ?…”