OH-H2 ENTRANCE CHANNEL COMPLEXES

The entrance channel to the OH + H2 → H2O + H hydrogen abstraction reaction has been investigated from several different experimental approaches and complementary theoretical calculations. Weakly bound complexes between the hydroxyl radical and molecular hydrogen have been stabilized within a shallow well in the entrance channel and characterized via electronic spectroscopy on the OH A2∑+- X2pi transition. Laser-induced fluorescence and fluorescence depletion experiments have revealed the binding energy of H2/D2 with ground state OH X2pi radicals, the intermolecular energy levels supported by the OH A2∑+ (v= o ,1)+H2/D2 potential, and the OH-H2/D2 excited state dissociation limit. TheOHX2pi+H2 potentials have also been examined through inelastic scattering measurements on 3-doublet state–selected OH with normal or para-H2. Finally, photodetachment of an electron from theH3O− anion enabled the neutral reaction to be probed in conformations sampled by the two isomeric forms of the anion.