Photoionization Resonance spectra of CO +2 and threshold electron—ion coincidence measurements of the fragmentation of CO +2

Abstract

Photoionization Resonance (PIR) spectroscopy has been used to study the vibrational and spin—orbit structure of the X̃, Ã, B̃ and C̃ states of CO + 2. We have determined directly the Renner—Teller spin—orbit interaction parameters for the X̃ state, the ionization potentials for all four states, the à state spin—orbit splitting and the v 1 frequency for the X̃, à and B̃ states. From coincidence measurements between threshold electrons and the ions produced, it was found that only O + + CO is produced at the CO + 2 (C̃) threshold — i.e., no CO + 2 was detected. It is further estimated that ca. 30% of the CO produced is in the v = 0 ground state. Finally, the PIR spectrum of CO + 2 just below the C̃ state suggests that the bond dissociation energy of CO 2 has an upper limit of about 5.44 eV.