Absorption Saturation Dynamics in Capped CdSe Microcrystallites Exhibiting Quantum Confinement

Abstract

We report the use of subpicosecond transient bleaching techniques to characterize the spectral dynamics and isolate the single particle spectrum of 32 angstrom CdSe nanoclusters. We observe strong bleaching of the localized, particle in a box transitions as well as the onset of induced absorption to the blue of the homo-lumo transition. The holewidth, bleaching, and induced absorption dynamics suggest that the initially photogenerated electron-hole pair rapidly relaxes to a long lived, (>1ns), trapped carrier configuration faster than 500fs. The quality of our samples allows us to resolvf the vibronic structure of the microcrystallite due to coupling of the exciton to the 200cm⁻¹ LOphonon and observe it’s effect upon the hole spectrum.