INVESTIGATION OF PHOTOCHEMICAL BEHAVIOR O F A SQUARAINE DYE PHOTOSENSITIZING TITANIUM-DIOXIDE ULTRAFINE PARTICLES

Photochemical behavior of -2-hydroxyphenyl)-4-(4-ethylaminophenyl)-squ araine (SQ) in TiO2 system was probed by UV-vis, fluorescence quenchin g, and nanosecond time-correlated single-photon counting. There was st rong interaction between SQ and TiO2 colloidal particles with an appar ent association constant of 2.275 x 10(3) mol(-1) dm(3) obtained by th e fluorescence quenching data. The fluorescence emission of SQ dye cou ld be quenched by TiO2 colloid with an efficiency of 97 %.The mechanis m of photoinduced interface electron transfer for the fluorescence que nching was proposed upon the spectral characters, potential discrepanc y and the variation of the fluorescence lifetime. The rate constant fo r the electron injection process was 1.97 x 10(8) s(-1) determined fro m the measurements of fluorescence lifetimes.