Ion-momentum imaging of dissociative-electron-attachment dynamics in acetylene

Abstract

We present experimental results for dissociative electron attachment to acetylene near the 3 eV ${}^{2}{\ensuremath{\Pi}}_{g}$ resonance. In particular, we use an ion-momentum imaging technique to investigate the dissociation channel leading to ${\mathrm{C}}_{2}{\mathrm{H}}^{\ensuremath{-}}$ 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 ab initio electronic structure and fixed-nuclei scattering calculations we obtain good agreement with the experiment.