A photoionization study of the formation of CO+2 by reaction of excited O+2 ions with CO

The production of CO+2 by the ion–molecule reaction O+2+CO→CO+2+O has been investigated using a photoionization mass spectrometer. The photoionization efficiency for production of CO+2 by this reaction was measured from threshold at 924 Å (13.42 eV) to 650 Å (19.07 eV). The appearance potential corresponds to reaction of O+2(X 2Πg) ions formed in the v′=6 level. The high vibrational level ions of the ground ionic state are most likely produced by autoionization of O2. At wavelengths shorter than 760 Å there is a large increase in the reaction cross section associated with formation of ions in the a 4Πu state. The peak reaction cross section occurs at 720 Å.