Resonant vibrational-excitation cross sections and rate constants for low-energy electron scattering by molecular oxygen

TL;DR

This paper calculates detailed electron scattering cross sections and rate constants for all vibrational levels of molecular oxygen, considering rotational effects and resonant states, across two energy regions, aiding plasma and atmospheric modeling.

Contribution

It provides comprehensive vibrational and rotational-resolved cross sections for electron-O2 scattering using advanced R-matrix and boomerang models, including resonance effects and energy-dependent features.

Findings

Resonant states significantly influence scattering cross sections.

Rotational motion impacts the cross section calculations.

Results align with existing experimental and theoretical data.

Abstract

Resonant vibrational-excitation cross sections and rate constants for electron scattering by molecular oxygen are presented. Transitions between all 42 vibrational levels of O$_2(\textrm{X}\ ^3\Sigma_g^- $) are considered. Molecular rotations are parameterized by the rotational quantum number $J$ which is considered in the range 1 to 151. The lowest four resonant states of O$_2^-$, $^2\Pi_g$, $^2\Pi_u$, $^4\Sigma_u^-$ and $^2\Sigma_u^-$, are taken into account. The calculations are performed using the fixed-nuclei R-matrix approach to determine the resonance positions and widths, and the boomerang model to characterize the nuclei motion. Two energy regions below and above 4~eV are investigated: the first one is characterized by sharp structures in the cross section, and the second by a broad resonance peaked at 10~eV. The computed cross sections are compared with theoretical and experimental results available in literature for both the energy regions, and are made available for use by modelers. The effect of including rotational motion is found to be non-negligible.