Excitons recombination investigation in CdSe/ZnS quantum dots solutions by pump–probe technique

Abstract

It reports results of the pump–probe experiment on colloidal solutions of semiconductor CdSe/ZnS quantum dots with 5 nm diameter for intense pulsed resonant excitation at 560 nm wavelength. The dependence of intensity of a transmitted probe pulse on time delay relative to the pump pulse was used to determine relaxation time τ_exc of excited excitons in the QDs. The intensity of nonlinear reducing of QDs solution transmittance served the reason to set it for pump pulse. We found that the excited states in the QDs recombine within 300 ps after interaction with a 20-ps pump pulse.