Electron-impact dissociation of carbon monoxide

The electron-impact dissociation of CO to form C and O atoms is observed in a crossed beam experiment at electron energies between the dissociation threshold (14 eV) and 198.5 eV. The center-of-mass energy released in the dissociation of individual molecules is explicitly measured using a position and time sensitive detector for the correlated neutral fragments. The observed energy release distribution is found to be highly structured, reflecting electron-impact excitation to Rydberg states converging to CO+(X 2Σ+) which predissociate to ground state atoms. Little or no dissociation is observed from states above the first ionization limit. Total electron impact dissociation cross sections, exclusive of dissociative ionization contributions, and partial cross sections for the dissociative excitation of specific CO electronic states are presented.