State-resolved exciton dynamics in quantum dots

The elementary excitation in semiconductor quantum dots is the exciton, an excited electron-hole pair. The size and geometry of the dot confines the exciton thereby yielding quantum confinement effects. The simplest examples of size quantization effects include the spectrum of single exciton states which dominate the linear absorption spectrum and the Stokes shift for the spontaneous photoluminescence spectrum. Here, we report on our recent results exploring the structure and dynamics of both single excitons and multi-excitons in colloidal CdSe quantum dots using femtosecond state-resolved pump/probe spectroscopy. These experiments have revealed tremendous insight into the relaxation pathways of hot excitons, new aspects of exciton-phonon interactions, and in the first observation of the electronic structure of multi-excitons.