Crossed-beam study of the reactions of H2+ with D2 and D2+ with H2

The reactions D2+ + H2 → D2H+ + H and H2++D2→(H2D+, D2H+)+(D,H) have been studied using the crossed-beam apparatus EVA. Sample contour velocity distributions of product ions have been obtained at relative kinetic energies between 0.4 and 5 eV. In addition potential energy surfaces were constructed for H4+ by the diatomics-in-molecules method and representative geometries were investigated. The experimental results are consistent with the predominant early downhill nature of the ground-state surface, in that a direct mechanism is observed at all energies studied. As the reactants approach one another, avoided surface crossings leading to charge transfer are accessible. Because of the occurrence of repeated electron jumps, the initial identity of the molecular ion is largely inconsequential and it is meaningless to label the mechanism as atom or ion transfer. (Auth.)