Electronic energy transfer in near-resonant electron capture collisions of H+2 with metal atoms: Radiative and nonradiative transitions

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Abstract
Modes of energy disposal in electron capture of H+2 with metal atoms (Cs, K, Mg, and Zn) for ion velocities in the range 3–7×107 cm/s are examined using combined optical and beam scattering techniques. Radiative and nonradiative transitions are observed for processes occurring under near resonant conditions. The following branching sequences are identified: Branching ratios are dependent on the vibrational state and the nuclear separation (Franck–Condon factors) of the H+2 ion at the time of electron capture. The branching ratio decreases for the (triplet)/(singlet) formation for H2 produced from reactions of vibrationally relaxed H+2 ion with K or Cs. Under conditions of H+2 ion relaxation, the kinetic energy of scattered atomic hydrogen following radiative decay from 3Σ+g state of H2 increases, implying a shift in the 3Σ+g→3Σ+u continuum toward longer wavelengths. The results also show that, at these velocities, the reations occur under near‐resonant conditions with vertical transitions.