Transient species produced by flash photolysis of acid solutions of methylene blue

Abstract

The spectral and temporal characteristics of the transient absorptions produced by flash photolysis of solutions of methylene blue in ethanol containing different amounts of acid are reported. A transient species with an absorption maximum at 380 nm and a lifetime of 4 µs is observed in acid solution and rate constants for the reactions of this species with oxygen and other quenchers were determined. It is suggested that the transient species is a semi-reduced methylene blue free radical.