Photoinduced interaction between xanthene dyes and colloidal CdS nanoparticles

Xanthene derivatives namely fluorescein, eosin, erythrosine and rose bengal were examined as sensitizers for colloidal CdS nanoparticles. The interaction of these dyes with colloidal CdS nanoparticles was studied by absorption, infra-red, steady state and time resolved fluorescence spectroscopic measurements. The adsorption of dyes on the surface of colloidal CdS nanoparticles through electrostatic interaction was observed. This adsorption leads to increase in optical density as well as quenching of the emission intensity of dye molecules. The apparent association constant was calculated from fluorescence data. The fluorescence quenching is attributable to electron transfer from excited state dyes to the conduction band of colloidal CdS is established.