Dynamics of proton transfer from ArH+ to CO

The reaction of ArH+ with CO is a fast proton transfer reaction that can form two different isomers, HCO+ and HOC+. It has been investigated in a crossed beam experiment and with direct dynamics simulations at collision energies ranging from 0.4 to 2.4 eV. Images of the differential cross sections reveal dominant forward scattering, which is evidence for direct dynamics. The measured product internal energies are primarily determined by the reaction enthalpy and only at large scattering angles depend noticeably on the collision energy. The computational results agree well with the measured internal energy and scattering angle distributions and with the previously measured total rate constant. The direct reaction dynamics with dominant forward scattering are well reproduced by the almost step like opacity functions. The HCO+/HOC+ branching is found to be close to 2:1 in the simulations at 0.83 eV and 2.37 eV collision energy. A mode-specific vibrational analysis provides further insight into the isomer specific distribution of the product internal excitation. (C) 2018 Elsevier B.V. All rights reserved