The absorption of light by small particles of semiconductors in solution can catalyze reactions of adsorbed species. Little work has been done on the picosecond charge recombination dynamics in semiconductor particles, in part, because of low luminescence quantum yields. A very sensitive, nonlinear optical technique has been extended to monitor charge carrier lifetimes in semiconductor particles without reliance on luminescence and will be applied to a number of colloid systems. The microscopic molecular reaction dynamics of adsorbed species at the liquid/solid interface are almost completely unexplored. The reaction dynamics of model surface adsorbed species that undergo chemical change following charge transfer from the semiconductor particle will be examined by dependable picosecond spectroscopic techniques. Experiments will be undertaken to explore the role of interactions between adsorbate, surface, and solvent on chemical reaction dynamics. The new information obtained will help provide a basis for development of interfacial reaction dynamics theory.
