Observation of the indirect (e, 3e) process of CO

We report an experimental investigation of the dissociative double ionization of CO induced by electron impact at an incident energy of 380 eV. The fragment ions (C+/O+) and one emitted electron were measured in coincidence by utilizing the COLTRIMS technique. The kinetic-energy-release (KER) of the fragment ions and the energy of the outgoing electron are obtained. Based on the characteristics of the KER distribution and the energy spectrum of the emitted electron, direct and indirect double ionization ((e, 3e)), including an autoionization process, were identified, respectively.