Energetic and Angular Studies of ArD+ and N2D+ Formation

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Abstract
The reactions Ar++D2→ArD++D and N2++D2→N2D++D have been studied with an angular ion‐scattering apparatus at ion laboratory energies in the range 2–100 eV. Kinetic‐energy distributions as well as angular distributions of the product ions have been determined. The experimental method consists of directing a mass‐analyzed and velocity‐selected ion beam into a collision chamber containing target gas at low pressure. The product ions are velocity analyzed with a 127° electrostatic velocity selector and mass analyzed in a quadrupole field radio‐frequency mass filter. The product‐ion analysis and detection system rotates about the center of the scattering region. It is found that the observed Q values for these reactions (where Q is the energy transformed from internal to translational) show a marked dependence on the primary‐ion kinetic energy, E1. The Q values for both reactions are endothermic over the entire energy range of these experiments, being approximately zero at the lowest energies and exhibiting endothermic maxima in the region 50<E1+ and N2D+ ions, with excitation energies approximately equal to the dissociation energies for ArD+→Ar+D+ and N2D+→N2+D+. The product‐ion kinetic‐energy distributions also give evidence of back scattering in the center‐of‐mass system. The energetic and angular features of both reactions are essentially the same, indicating that the collision mechanisms leading to the formation of both product ions do not differ significantly. The experimental results indicate that both reactions proceed according to a ``pickup'' mechanism at moderate coilision energies. At very low collision energies the results suggest that complex formation may become important.