Subpicosecond spectroscopic studies of photochemical events involving thioglycerol-capped cadmium sulfide particles

Abstract In order to elucidate the dynamics of electrons and holes photoproduced on the surface-modified semiconductor Q-particles, subpicosecond laser flash photolysis of thioglycerol-capped cadmium sulfide (TG-CdS) particles was carried out in various solvents. The transient absorption due to electrons and holes photoproduced on TG-CdS particles was observed immediately after subpicosecond laser pulse excitation. The transient absorption is larger in water than in water + acetonitrile (4 : 1) and dimethylformamide (DMF). The difference among them may be attributable to the production of hydrated electrons. The decay process of the transient absorption can be classified roughly into three groups as follows; (1) the fast one decaying within a few picoseconds due to electron–hole recombination in which plural electron–hole pairs participate, (2) the second one with life time of several tens to several hundred picoseconds due to normal electron–hole recombination and (3) the third component concerning with hydrated electrons which does not decay up to several nanoseconds. In DMF, however, the third component was not observed. The relative ratio among three decay components depends on solvents.