Fragmentation dynamics in dissociative electron attachment to CO probed by velocity slice imaging

Abstract

Complete dissociation dynamics in electron attachment to carbon monoxide (CO) have been studied using the newly developed velocity slice imaging (VSI) technique. Both kinetic energy and angular distributions of O(-) ions formed by dissociative electron attachment (DEA) to CO molecules have been measured for 9, 9.5, 10, 10.5, 11, and 11.5 eV incident electron energies around the resonance. Detailed observations conclusively show that two separate DEA reactions lead to the formation of O(-) ions in the ground (2)P state along with the neutral C atoms in the ground (3)P state and the first excited (1)D state, respectively. Within the axial recoil approximation and involving four partial waves, our angular distribution results clearly indicate that the two reactions leading to O(-) formation proceed through the specific resonant state(s). For the first process, more than one intermediate state is involved. On the other hand, for the second process, only one state is involved. The observed forward-backward asymmetry is explained in terms of the interference between the different partial waves that are involved in the processes.

Higher lying resonances in low-energy electron scattering with carbon monoxide*

“…The DEA experiments suggest that there are two 2 Σ + resonances between 10 eV and 11 eV [17][18][19][20][21][22][23]. Our calculations detected only a single 2 Σ + resonance at 12.9 eV.…”

“…More recently, experimental DEA studies were undertaken by Nag and Nandy [23] and Tian et al [24]. These studies proved somewhat controversial regarding the nature of the resonances involved.…”

“…However, experimentally it has long been known that CO can undergo dissociative electron attachment (DEA) with two peaks at about 10.2 and 10.9 eV [17][18][19][20][21][22][23] and the main product of this is C+O − , although C − +O has also been observed [18]. The precise physics of the states contributing to the DEA process has recently proved somewhat controversial [23][24][25][26][27].…”

Dissociative electron attachment to CO molecule probed by velocity slice imaging technique

“…Only one angular distribution measurement over limited angular range by Hall et al [5] concluded a TNI state with Π symmetry is responsible for both the processes. In the recent times, the momentum imaging techniques [6,7,8] have been used to understand the complete dynamics in DEA to CO molecule.…”

“…The authors introduced coherent interference The electron beam direction is from left to right and passing through the centre of the images. Graphs have been taken from [7].…”