Dipolar dissociation dynamics in electron collisions with oxygen molecules

TL;DR

This study investigates the dipolar dissociation of oxygen molecules caused by electron collisions in the 21-35 eV range, analyzing the process thresholds, fragment energies, and angular distributions using velocity map imaging.

Contribution

It provides new insights into the dissociation mechanisms, including the roles of Rydberg states and ion-pair states, with detailed kinetic and angular distribution measurements.

Findings

Dipolar dissociation occurs via Rydberg state pre-dissociation at lower energies.

Direct excitation to ion-pair states dominates at higher energies.

Kinetic energy and angular data reveal state symmetry and excitation pathways.

Abstract

The dipolar dissociation of molecular oxygen due to 21-35 eV energy electron collision has been studied using the time sliced velocity map imaging technique. A rough estimation about the threshold of the process and the kinetic energy and angular distribution of the fragment negative ions are measured. The dipolar dissociation found to be occur due to pre-dissociation of a Rydberg state via ion-pair state for lower incident electron energies as well from also direct excitation to the ion-pair states for relatively higher primary beam energy. The location and symmetry of the excited states were determined from the kinetic energy and angular distribution data respectively.