Search for Singlet Oxygen Luminescence in the Disproportionation of Ho2/O2

During the reaction HO2+ HO2 (or O2‐) = H2O2+ O2 in aqueous solution, no luminescence in the region 620–720 nm, expected if the product O2 were formed in a singlet state, could be detected. If any singlet O2 is formed, its yield must be less than 10%. Faint luminescence, sometimes found at shorter wavelengths, was shown to arise from reaction of HO2 with impurities in the reagents present.