Formation of HO2+ by reaction of metastable O2+ ions with H2

The photoionization efficiency curves of H2+, O2+, and HO2+ have been studied in a mixture of hydrogen and oxygen over the wavelength range 650–810 Å. The HO2+ ion appears at 804 Å, the threshold for ionization of H2, by the reaction H2+ + O2 → HO2+ + H. The relative photoionization efficiency curves of H2+ and HO2+ are the same from 804 to 764 Å. Below 764 Å production of the a 4Πμ metastable electronic state of O2+ leads to the formation of HO2+ by the reaction O2+ (a 4Πu) + H2 → HO2+ + H.