Femtosecond studies of interfacial electron-hole recombination in aqueous CdS colloids

Abstract

We report the measurements of the electron-hole recombination rate in aqueous CdS colloids on the femtosecond time scale. A fast 2-ps decay and a slower 45-ps decay have been observed, and the decay dynamics are found to be very sensitive to the excitation laser intensity. Geminate electron-hole recombination, responsible for the 45-ps decay, dominates the decay process at low excitation intensities, while nongeminate recombination, accounting for the 2-ps decay, becomes more important at high excitation intensities.