Ion-momentum imaging of dissociative electron attachment dynamics in acetylene

TL;DR

This study uses ion-momentum imaging to explore the dissociative electron attachment process in acetylene, revealing detailed fragment dynamics and bending behavior near a specific resonance, supported by theoretical calculations.

Contribution

It provides new experimental ion-momentum data and theoretical modeling of dissociation dynamics in acetylene at the 3 eV resonance.

Findings

Observation of significant bending dynamics during dissociation.

Good agreement between experimental data and ab initio calculations.

Identification of kinetic energy and angular distributions of fragments.

Abstract

We present experimental results for dissociative electron attachment to acetylene near the 3 eV $^2\Pi_g$ resonance. In particular, we use an ion-momentum imaging technique to investigate the dissociation channel leading to C$_2$H$^-$ fragments. From our measured ion-momentum results we extract fragment kinetic energy and angular distributions. We directly observe a significant dissociation bending dynamic associated with the formation of the transitory negative ion. In modeling this bending dynamic with \emph{ab initio} electronic structure and fixed-nuclei scattering calculations we obtain good agreement with the experiment.