Theoretical study of ArH+ dissociative recombination and electron-impact vibrational excitation

TL;DR

This theoretical study calculates dissociative recombination and vibrational excitation cross sections for ArH+ ions at interstellar energies, revealing very low recombination rates below 1000K that explain its observed abundance.

Contribution

It provides detailed quantum mechanical calculations of ArH+ reaction rates using R-matrix and Multichannel Quantum Defect Theory methods, advancing understanding of interstellar chemistry.

Findings

Very low dissociative recombination rate below 1000K

Results align with previous experimental upper limits

Supports the presence of ArH+ in interstellar environments

Abstract

Cross sections are presented for dissociative recombination and electron-impact vibrational excitation of the ArH+ molecular ion at electron energies appropriate for the interstellar environment. The R-matrix method is employed to determine the molecular structure data, i.e. the position and width of the resonance states. The cross sections and the corresponding Maxwellian rate coefficients are computed using a method based on the Multichannel Quantum Defect Theory. The main result of the paper is the very low dissociative recombination rate found at temperatures below 1000K. This is in agreement with the previous upper limit measurement in merged beams and offers a realistic explanation to the presence of ArH+ in exotic interstellar conditions.