Orientation-dependent dissociative charge transfer

Recoil-ion momentum spectroscopy and molecular fragment imaging techniques are combined to study dissociative electron capture from He by HeH+ at 0.20-a.u. collision velocity. Groups of final HeH states which dissociate to ground or excited H and He atoms are separated. For each group, the experiment provides two-dimensional H fragment distributions with respect to the collision plane and for fixed transverse momentum transfer. These patterns show that the capture probability is highest for HeH+ ions with their axis oriented normal to the scattering plane for two of the three groups populated. [S1050-2947(98)50201-6].