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 ²P state along with the neutral C atoms in the ground ³P state and the first excited ¹D 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.