Electrochemistry of Azine, Oxazine, and Thiazine Dyes

摘要

The role of short-lived intermediates of dyes such as methylene blue safranin-O, neutral red and oxazines used in the photosensitization of electrodes was studied by means of laser flash photolysis and voltammetry. The study include transients initiated by absorption of light by dyes in solution and by dyes absorbed on electrodes, with major emphasis on the transients arising from solution absorption. For each mode of photoexcitation the identity, the lifetime and the mechanism of formation and decay of the transient species was determined. Key variables examined systematically included pH, solvent composition, electrode material and potential, and reagents which selectively quench the excited state. The goal established the place of formation and the disappearance of each transient species in the overall photoelectrochemical process.