Photoelectrochemistry in particulate systems. Photosensitized charge injection into opaque TiO 2 semiconductor powder as probed by time-resolved diffuse reflectance laser flash photolysis

Abstract

Fluorescence emission of phenosafranin dye was quenched when this dye was adsorbed on TiO 2 particles. Diffuse reflectance laser flash photolysis measurements have shown transient absorption corresponding to the cation radical of phenosafranin when the dye adsorbed on TiO 2 was excited with a 532 nm laser pulse. The process of charge injection into TiO 2 particles was further confirmed by comparing the results of the diffuse reflectance and emission experiments with those from the dye-coated silica particles. Dependence of relative efficiency of charge injection on the surface coverage of the dye has also been elucidated.