Study of photoreduction kinetics of xanthene dyes with intersystem crossing from upper triplet states

TLDR: In this paper, a model of the kinetics of photoprocesses in polyatomic molecules based on four-level energy scheme is carried out, which includes the processes in dye under cw photoexcitation and takes into account a reverse intersystem crossing and photoochemical reaction from the upper triplet states.

Abstract: Modeling of kinetics of photoprocesses in polyatomic molecules based on four-level energy scheme is carried out. The model includes the processes in dye under cw photoexcitation and takes into account a reverse intersystem crossing and photochemical reaction from the upper triplet states. The analytical time-dependent relation for dye concentration of the initial form was obtained taking into account the contrast of rates of various photoprocesses and using of quasistationary approximation. It was shown that rate constant of photolysis correlates with probability of intersystem crossing of the dyes. For the xanthene dyes in gelatin it was shown that simple experimental method of cw laser photolysis combined with the kinetic model could be effective technique of study of upper excited states participation.