Rotational excitation of asymmetric-top molecular ions by electron impact: application to H$_2$O$^+$, HDO$^+$, and D$_2$O$^+$

TL;DR

This paper presents a theoretical study of electron-impact rotational excitation of asymmetric-top molecular ions H$_2$O$^+$, HDO$^+$, and D$_2$O$^+$, providing detailed cross sections and rate coefficients relevant for astrophysical and plasma environments.

Contribution

It introduces a combined theoretical framework, including adaptations of multichannel quantum-defect theory and Coulomb-Born approximation, for calculating excitation of asymmetric-top molecular ions.

Findings

State-resolved cross sections and rate coefficients are provided.

Calculations cover transitions from the ground state up to N=4.

Results are made available through the EMAA database.

Abstract

The rotational excitation of the three asymmetric-top molecular ion isotopologues H$_2$O$^+$, HDO$^+$, and D$_2$O$^+$ is studied theoretically using a combined framework of electron-molecule R-matrix scattering theory, multichannel quantum-defect theory, frame transformation theory, and the Coulomb-Born approximation. The latter two have been adapted here for asymmetric-top rotors. State-resolved cross sections and kinetic rate coefficients for transitions from the rotational ground state of the ions are presented. State-resolved rate coefficients for all calculated transitions $N=0\ldotstwo4$ are included as supplementary material and will be made available through the EMAA database.