Luminescence-based assessment of thermodynamic constants for electrostaticbinding of non-luminescent dyes and atomic ions to colloidal semiconductorsurfaces

Steady-state and time-resolved luminescence experiments were employed to st udy the electrostatic interaction of cationic photosensitizers and negative ly charged colloidal semiconductor particles. Electrostatic adsorption of e fficient photosensitizers on semiconductor surfaces is known to quench the photosensitizers' luminescence. By monitoring the quenching, either directl y or competitively, thermodynamic constants for binding of both luminescent and non-luminescent ruthenium and osmium. complexes to negatively charged SnO2 Particle have been determined. The function of atomic cations, such as Li+, Na+ and K+, in controlling the binding of cationic dyes to colloidal SnO2 has also been studied via competitive luminescence. From the study, se miconductor surface binding constants for these species have also been dete rmined. (C) 2001 Elsevier Science B.V. All rights reserved.