Differential Absorption Features of CdSe QDs in the Case of Resonant and Nonresonant Excitons Excitation

Nanosecond differential absorption measurements of spherical CdSe QDs at the quasi-stationary resonant and nonresonant excitation of basic exciton transitions are reported. The significant decrease in absorption and saturation of the basic exciton transition 1 S h 3/2 –1 S e are explained by the state filling effect. The observed blue shift of differential absorption minima with increasing pump intensities was explained by strong exciton–phonon interaction. In addition, the 2 S h 3/2 –1 S e exciton transition bleaching and induced absorption of mixed 1 P h 3/2 –1 P e and 2 S h 1/2 –1 S e exciton transitions were found.