title: A pulsed-field ionization photoelectron secondary ion coincidence study of the H2+ (X,upsilon+=0-15,N+=1)+He proton transfer reaction.
abstract: The endothermic proton transfer reaction, H2+(upsilon+)+He-->HeH+ + H(DeltaE=0.806 eV), is investigated over a broad range of reactant vibrational levels using high-resolution vacuum ultraviolet to prepare reactant ions either through excitation of autoionization resonances, or using the pulsed-field ionization-photoelectron-secondary ion coincidence (PFI-PESICO) approach. In the former case, the translational energy dependence of the integral reaction cross sections are measured for upsilon+=0-3 with high signal-to-noise using the guided-ion beam technique. PFI-PESICO cross sections are reported for upsilon+=1-15 and upsilon+=0-12 at center-of-mass collision energies of 0.6 and 3.1 eV, respectively. All ion reactant states selected by the PFI-PESICO scheme are in the N+=1 rotational level. The experimental cross sections are complemented with quasiclassical trajectory (QCT) calculations performed on the ab initio potential energy surface provided by Palmieri et al. [Mol. Phys. 98, 1839 (2000)]. The QCT cross sections are significantly lower than the experimental results near threshold, consistent with important contributions due to resonances observed in quantum scattering studies. At total energies above 2 eV, the QCT calculations are in excellent agreement with the present results. PFI-PESICO time-of-flight (TOF) measurements are also reported for upsilon+=3 and 4 at a collision energy of 0.6 eV. The velocity inverted TOF spectra are consistent with the prevalence of a spectator-stripping mechanism.
authors.affiliation: Department of Chemistry, University of California at Davis, Davis, California 95616, USA.
authors.forename: X N
authors.initials: XN
authors.lastname: Tang
authors.forename: H
authors.initials: H
authors.lastname: Xu
authors.forename: T
authors.initials: T
authors.lastname: Zhang
authors.forename: Y
authors.initials: Y
authors.lastname: Hou
authors.forename: C
authors.initials: C
authors.lastname: Chang
authors.forename: C Y
authors.initials: CY
authors.lastname: Ng
authors.forename: Y
authors.initials: Y
authors.lastname: Chiu
authors.forename: R A
authors.initials: RA
authors.lastname: Dressler
authors.forename: D J
authors.initials: DJ
authors.lastname: Levandier