An analytic model of rotationally inelastic collisions of polar molecules in electric fields

TL;DR

This paper introduces an analytic model based on Fraunhofer scattering to describe how electric fields influence rotationally inelastic collisions of polar molecules, providing insights into field-dependent scattering behaviors.

Contribution

The paper presents a new analytic model that predicts the effects of electric fields on molecular collision dynamics using Legendre moments and Fraunhofer scattering principles.

Findings

Model accurately predicts field-dependent scattering features.

Demonstrates electric field effects on phase and amplitude of scattering oscillations.

Qualitatively agrees with existing close-coupling calculations.

Abstract

We present an analytic model of thermal state-to-state rotationally inelastic collisions of polar molecules in electric fields. The model is based on the Fraunhofer scattering of matter waves and requires Legendre moments characterizing the "shape" of the target in the body-fixed frame as its input. The electric field orients the target in the space-fixed frame and thereby effects a striking alteration of the dynamical observables: both the phase and amplitude of the oscillations in the partial differential cross sections undergo characteristic field-dependent changes that transgress into the partial integral cross sections. As the cross sections can be evaluated for a field applied parallel or perpendicular to the relative velocity, the model also offers predictions about steric asymmetry. We exemplify the field-dependent quantum collision dynamics with the behavior of the Ne-OCS($^{1}\Sigma$) and Ar-NO($^2\Pi$) systems. A comparison with the close-coupling calculations available for the latter system [Chem. Phys. Lett. \textbf{313}, 491 (1999)] demonstrates the model's ability to qualitatively explain the field dependence of all the scattering features observed.