Angular distributions, kinetic energy distributions, and excitation functions of fast metastable oxygen fragments following electron impact on CO2

Dissociative excitation of CO2 by electron impact has been studied using the methods of translational spectroscopy and an angular distribution analysis. Earlier time-of-flight studies revealed two overlapping spectra, the slower of which has been attributed to metastable CO(a 3π) fragments. The fast peak is the focus of the present study. Threshold energy, angular distribution, and improved time-of-flight measurements indicate that the fast peak actually consists of five overlapping features. The slowest of the five features (1) is found to consist of the metastable O(5S) produced by predissociation of a Σu+ state of CO2 into O(5S) + CO(a 3π). Oxygen Rydberg fragments originating directly from a different Σu+ state are believed to make up the next fastest feature (2). Mechanisms for producing the three remaining features are discussed.