LASER PHOTOLYSIS OF 3‐METHYLLUMIFLAVIN

Abstract
—The pH dependence of the transient absorptions of 3‐methyllumiflavin has been investigated with laser photolysis in the nanosecond time range. Three different transient species (I, II and III) can be observed. The analysis of the decay curves shows that I and II can be ascribed to the optical absorption spectra of the lowest excited singlet and triplet states, respectively. Their appearance is not affected by a change of pH of the solution. The transient spectra due to species III have a decay which is dependent on pH. By comparison of these results with spectral data obtained with flavin dissolved in polymethylmethacrylate and with photochemical data reported in the literature, a structure for III is proposed which might explain the observed pH dependence.