Velocity Map Imaging Study of Charge-Transfer and Proton-Transfer Reactions of CH3 Radicals with H3(.).
The velocity map imaging method has been applied to crossed beam studies of charge transfer and proton transfer between methyl (CH3) radicals formed by pyrolysis and H3(+) cations over the collision energy range from 1.2 to 3.4 eV. Vibrational excitation in the H3(+) reactants plays an important role both in promoting endoergic charge transfer and in supplying energy to the products of the proton-transfer reaction. Excited H3(+) reactants with vibrational energy in excess of the barrier lead to energy-resonant charge transfer via long-range collisions. A small fraction of collisions that take place at low impact parameters appear to form charge-transfer products with higher levels of internal excitation. The proton-transfer reaction exhibits direct, stripping-like dynamics. Consistent with the kinematics of proton transfer, incremental kinetic energy supplied to the reactants is strongly directed into product relative kinetic energy, as predicted by the concept of "induced repulsive energy release".
†Department of Chemistry, University of Rochester, Rochester, New York 14627, United States.
Linsen
L
Pei
‡Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria.
Eduardo
E
Carrascosa
†Department of Chemistry, University of Rochester, Rochester, New York 14627, United States.
Nan
N
Yang
§Dipartimento di Ingegneria Civile ed Ambientale, Università degli Studi di Perugia, 06125 Perugia, Italy.
Stefano
S
Falcinelli
†Department of Chemistry, University of Rochester, Rochester, New York 14627, United States.
James M
JM
Farrar
Franck−Condon factor; crossed beams; ion imaging; ion−radical collisions; reaction dynamics; vibrational excitation