A model analysis of rotationally inelastic Ar + H$_2$O scattering in an electric field

TL;DR

This paper presents an analytic model for rotationally inelastic collisions of asymmetric-top molecules with atoms in electric fields, applied to Ar--H$_2$O, predicting field-dependent collision features testable experimentally.

Contribution

It introduces a new analytic model for state-to-state collision cross sections of asymmetric-top molecules in electric fields, specifically applied to Ar--H$_2$O, highlighting field effects on collision dynamics.

Findings

Predicted cross sections show field-dependent features up to 150 kV/cm.

Certain collision channels are sensitive to electric field-induced state hybridization.

Averaging over product channels diminishes the orientation effects caused by the electric field.

Abstract

We develop an analytic model of thermal state-to-state rotationally inelastic collisions of asymmetric-top molecules with closed-shell atoms in electric fields, and apply it to the Ar--H$_2$O collision system. The predicted cross sections as well as the steric asymmetry of the collisions show at fields up to 150 kV/cm characteristic field-dependent features which can be experimentally tested. Particularly suitable candidates for such tests are the $0_{00} \to 2_{20}$ and $1_{01} \to 2_{21}$ channels, arising from the relaxation of the field-free selection rules due to the hybridization of $J$ states. Averaging over the $M'$ product channels is found to largely obliterate the orientation effects brought about by the field.