Dissociative recombination of the hydrogen molecular ion

Abstract

Recent experiments on the dissociative recombination of H₂⁺ and D₂⁺ are summarized and the projection operator formalism of resonance scattering processes in molecules is reviewed. The application of the theory to specific systems requires the calculation of electronic energies and matrix elements, and of vibrational wavefunctions; comprehensive results are presented for H₂⁺ and D₂⁺. To obtain further insight the author develops a semiclassical theory which is surprisingly successful; in particular the cross sections for producing atoms in high Rydberg states are predicted to be large, in agreement with experiment. The rate of recombination at thermal energies (<300K) requires special consideration: it is shown that the so-called indirect mechanism is significant and that the total thermal rate is reasonably fast.