title: Evidence for excited spin-orbit state reaction dynamics in F+H2: theory and experiment.
abstract: We describe fully quantum, time-independent scattering calculations of the F+H2-->HF+H reaction, concentrating on the HF product rotational distributions in v'=3. The calculations involved two new sets of ab initio potential energy surfaces, based on large basis set, multireference configuration-interaction calculations, which are further scaled to reproduce the experimental exoergicity of the reaction. In addition, the spin-orbit, Coriolis, and electrostatic couplings between the three quasidiabatic F+H2 electronic states are included. The calculated integral cross sections are compared with the results of molecular beam experiments. At low collision energies, a significant fraction of the reaction is due to Born-Oppenheimer forbidden, but energetically allowed reaction of F in its excited (2P 1/2) spin-orbit state. As the collision energy increases, the Born-Oppenheimer allowed reaction of F in its ground (2P 3/2) spin-orbit state rapidly dominates. Overall, the calculations agree reasonably well with the experiment, although there remains some disagreement with respect to the degree of rotational excitation of the HF(v'=3) products as well as with the energy dependence of the reactive cross sections at the lowest collision energies.
authors.affiliation: Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland, 20742-2021, USA.
authors.forename: François
authors.initials: F
authors.lastname: Lique
authors.forename: Millard H
authors.initials: MH
authors.lastname: Alexander
authors.forename: Guoliang
authors.initials: G
authors.lastname: Li
authors.forename: Hans-Joachim
authors.initials: HJ
authors.lastname: Werner
authors.forename: Sergey A
authors.initials: SA
authors.lastname: Nizkorodov
authors.forename: Warren W
authors.initials: WW
authors.lastname: Harper
authors.forename: David J
authors.initials: DJ
authors.lastname: Nesbitt