Dissociative excitation of CO by electron impact: translational spectroscopy of long-lived high-Rydberg fragment atoms

Carbon and oxygen atoms in long-lived high-Rydberg states have been produced by the electron impact dissociative excitation of CO. The observed time-of-flight distributions and excitation functions reveal seven dissociation processes; appearance potentials and dissociation limits have been determined for each of them. For the slowest high-Rydberg fragments the excitation function exhibits sharp, resonancelike structure near threshold. These data are analyzed by the core-ion model of high-Rydberg dissociation, in which the Rydberg electron acts as a spectator to the dissociation process. The observed dissociation limits involve high-Rydberg atomic fragments with ground state ion cores. Available data on the dissociative states of CO+ and CO++ and on the kinetic energy distributions for C+ and O+ measured by dissociative ionization experiments are discussed and compared to the high-Rydberg results.