Structure of excited-state transitions of individual semiconductor nanocrystals probed by photoluminescence excitation spectroscopy

The structure of excited-state transitions of individual semiconductor nanocrystals (NC) was analyzed using photoluminescence excitation (PLE) spectroscopy. The observations were rationalized by analyzing hole intraband relaxation behavior. The PLE spectra of individual NC show a few sharp band-edge peaks that can be explained in terms of a fine-structure splitting of the lowest exciton state. A sharp drop in relaxation rates near the band edge explains the development of sharp PLE features at low spectral energies.