QUASI-BOUND ELECTRONIC STATES OF CO-2+

Quasibound electronic states of the CO2+ ion are investigated by means of photoion-photon-of-fluorescence coincidence (PIFCO) and ion kinetic energy spectroscopy (IKES) methods. Energies of the lowest four electronic states (3 Pi, 1 Sigma +), 3 Pi, 3 Sigma + and 1 Pi are accurately measured at 41.25+or-0.05, 41.3+or-0.1, 41.8+or-0.1 and 43.8+or-0.1 eV respectively. The latter two states dissociate in less than 1 mu s, while the 3 Pi and 1 Sigma 1 states can survive for a few mu s. Furthermore, the lack of detected fluorescence is discussed and an upper bound is derived for the fluorescence efficiency of CO2+. © 1990 Elsevier Science Publishing Co., Inc.