Monitoring the formation and decay of singlet molecular oxygen in TiO2 photocatalytic systems and the reaction with organic molecules

By monitoring the time profiles of O-1(2) at the 1270-nm band, the reaction of singlet molecular oxygen (O-1(2)) with four kinds of organic molecules, methionine, pyrrole, collagen, and folic acid was examined in photocatalytic systems of TiO2 aqueous suspension. A fast decay observed in 1.5 mu s after the pulse excitation attributable to the fast reaction of formed O-1(2) with these molecules. From the analysis of the decay profiles, it is concluded that the organic molecules should be adsorbed on the TiO2 surface to react with O-1(2).