State selected ion–molecule reactions by a coincidence technique. XV. Hydrogen atom abstraction as an electron jump followed by proton transfer in the ND+3 (v)+NH3 and NH+3 (v)+ND3 reactions

Abstract

The effects of the vibrational excitation of the ν2 mode of ND+3 (v) and NH+3 (v) on the three channels of their reaction with NH3 and ND3 , respectively, are investigated up to v=12 in the center-of-mass kinetic energy range from 0.9 to 4.5 eV by use of the TESICO technique. The ratio (γ) of the hydrogen/deuterium atom abstraction cross section over the competing deuteron/proton transfer cross section has a maximum systematically at a vibrational level (vmax ) slightly higher than that giving maximum Franck–Condon factor (vFC ) for the neutralization of ND+3 (v)/NH+3 (v). A new reaction model based on a nonadiabatic transition theory and the potential energy surface calculated for the ammonia dimer cation is proposed to explain the experimental results. The hydrogen/deuterium atom abstraction reaction is interpreted as a near resonant electron jump at larger intermolecular separation followed by proton/deuteron transfer which proceeds on the ‘‘electron (charge)–transferred’’ potential surface.