Formation of O3+ by the reaction of metastable O2+ ions with O2

The production of O3+ by the ion-molecule reaction O2+ (a 4Πu) + O2 → O3+ + O was investigated using a photoionization mass spectrometer. The photoionization efficiency for production of O3+ by this reaction was measured from threshold at 742±2 Å (16.71±0.05 eV) to 650 Å (19.07 eV). The appearance potential of the O3+ ion corresponds to reaction of O2+ ions initially formed in the v′=5 vibrational level of the a 4Πu state.