Mechanisms for O− electron stimulated desorption via dissociative attachment in condensed CO

The formation of O− ions via dissociative attachment (DA) in electron stimulated desorption from condensed CO is reported. The 2Π states of CO− previously observed in the gas phase and CO− states with the forbidden symmetry Σ− are involved below and above 13 eV, respectively, in the DA processes. Measurements of the kinetic energy of O− ions indicate that they suffer post dissociation interactions with the neighboring CO molecules before leaving the solid.