Dynamics of Chemical and Charge-Transfer Reactions of Molecular Dications. IV. Proton Transfer and Reactions of Dication Isomers in the CHCl2+ + D2 System

Chemical reactions and charge-transfer processes in the CHCl 2+ + D 2 system were investigated in crossed-beam scattering experiments. Experimental data were complemented by theoretical calculations of the energetics of the species involved and by calculations of stationary points on the dication potential energy surfaces. The main reaction products were the cations CHCl +, CHDCl +, and CCl + . Integral cross sections for the formation of these species were determined over the collision-energy range of 0.4−2.5 eV (center of mass). Two isomers of the reactant dication were identified, with the H atom being bonded either to a C atom (HCCl 2+ ) or to a Cl atom (CClH 2+ ). The isomer CClH 2+, which has a higher ionization energy than HCCl 2+, was determined to be responsible for most of the charge-transfer product (the formation of the ground and excited states of CClH + ). The chemical reaction product CHDCl + was formed in two processes of different translational-energy release via a long-lived or short-lived intermediate, and it could originate from both reactant dication isomers. The most abundant reaction product, CCl +, was formed mostly by a highly exoergic impulsive process of proton transfer from the ground state of the dication HCCl 2+ to D 2 . This direct reaction of proton transfer seems to be a rather general chemical process in collisions of hydrogen-containing dications with neutrals of some proton affinity.