Summary: Vibrational mode and collision energy effects on proton transfer in phenol
cation­methylamine collisions
Ho-Tae Kim, Richard J. Green, and Scott L. Andersona)
Department of Chemistry, University of Utah, 315 S. 1400 E. Rm 2020, Salt Lake City, Utah 84112-0850
Received 28 January 2000; accepted 29 March 2000
Mass-analyzed threshold ionization has been used to prepare vibrationally state-selected phenol
cations, that were then reacted with methylamine at collision energies ranging from 0.1 to 2 eV.
Integral cross sections and product recoil velocity distributions are reported. Ab initio calculations
of stationary points on the surface and RRKM Rice­Ramsperger­Kassel­Marcus analysis of
complex lifetimes are also presented for comparison. The only reaction observed over the entire
energy range is exoergic proton transfer PT . For ground-state reactants, the PT cross section is
reduced by increasing collision energy, such that the reaction efficiency declines from 71% at low
Ecollision to 50% at 2 eV. Excitation of either v6a or v12 vibrations inhibits reaction over the entire
collision energy range, with the effect being somewhat mode-specific and increasing with increasing
Ecollision . At low Ecollision , both vibrational and collision energy inhibit reaction with similar
efficiency. Collision energy effects diminish at high Ecollision , while vibration continues to have a
strong effect. Product ion velocity distributions are approximately forward­backward symmetric at
Ecollision 1 eV, but are backward peaked at high energies. Mechanistic implications of these results
are discussed. © 2000 American Institute of Physics. S0021-9606 00 00724-8
I. INTRODUCTION

Source: Anderson, Scott L. - Department of Chemistry, University of Utah

Collections: Energy Storage, Conversion and Utilization; Materials Science; Chemistry