Very low energy scattering in HH⁺ and HD⁺

Abstract

Differential and total cross sections for elastic scattering and resonant–near-resonant charge exchange have been computed for H+–H(1s) and H+–D(1s) collisions in the energy range 0 to ~0.1 eV, using a rigorous quantum mechanical formulation of slow collision theory in which all spurious couplings of the perturbed stationary states (PSS) theory are removed. Orbiting and shape resonances are described and compared in the two systems, and in addition the distinctive features of the HD+ case, such as the appearance of several Feshbach resonances in the region below the D+–H(1s) threshold, are identified and discussed. Most of the effects of the isotopic H(1s)–D(1s) splitting disappear at collision energies near the end of this range.

Charge exchange in slow H++ D(1s) collisions

“…The lack of structure in Hunter and Kuriyan's (1977b) calculation can be accounted for by differences in the numerical energy mesh. Note, however, that Hunter and Kuriyan's cross sections appear 5-10% lower than those of Davis and Thorson from 30 to 100 meV, due to the accidental overlap of their calculated points with the minima in the oscillations of the calculated values of Davis and Thorson (1978). The truncated set of two-centre coupled radial wave equations derived by Hunter and Kuriyan was solved more recently using a different numerical technique (Hodges and Breig 1993) and those results did show additional features not seen in the original calculations.…”

Rate Coefficients for D(1s) + H+⇆ D+ + H(1s) Charge Transfer and Some Astrophysical Implications

“…Several other groups have carried out detailed calculations for σ 1 and σ 2 . Davis & Thorson (1978) published results for σ 1 from 3.7 to ≈ 100 meV. Results for σ 1 and σ 2 were reported by Hunter & Kuriyan (1977) for energies from 10 −3 to 7.5 eV, by Hodges & Breig (1993) from 10 −3 to 10 eV, and by Esry et al (2000) from ≈ 3.7 meV to 8 eV.…”

Microwave electronic spectrum of the He+2 ion

“…In HD ϩ the long-range excited electronic state correlates with the higher dissociation limit; all the vibration-rotation levels of this state lie above the lower dissociation limit, however, and are calculated to predissociate rapidly. 19,20 Consequently, a resolved electronic spectrum is not expected and it would, in any case lie well outside the microwave region. We were able to study rotational transitions involving the high-lying vibration-rotation levels of the ground state, which correlates with the lower dissociation limit, and to demonstrate through nuclear hyperfine measurements the remarkable asymmetry in the electron distribution.…”