Dissociative recombination of electrons with diatomic molecular cations above dissociation threshold: Application toH2+andHD+

Abstract

Our approach to the dissociative recombination and competitive processes based on the multichannel quantum defect theory is extended to the full account of the dissociative excitation, including the electronic excitation of the molecular ion. Compared to other existing modelings, ours relies on a simpler and less-time-consuming discretization of the vibrational continua of the target ion and to a more accurate account of the Rydberg-valence interactions via a second-order solution of the Lippman-Schwinger equation. A thorough study of the competition among the dissociative recombination, vibrational excitation, and dissociative excitation is performed, including a detailed analysis of the two different mechanisms governing the ion dissociation. The application of our method to the high-energy electron collisions with ${{\mathrm{H}}_{2}}^{+}$ and ${\mathrm{HD}}^{+}$ ions results in a cross section in good agreement with the best previous modeling and with the most recent measurements performed in the Test Storage Ring of the Max-Planck-Institut f\"ur Kernphysik in Heidelberg.