Hot luminescence of CdSe nanoparticles at low temperature

We report experimental and theoretical study of low-temperature photoluminescence (PL) spectra of CdSe nanoparticles under resonant excitation. We find that under resonant excitation of the dots, the otherwise broad emission band evolves into a series of multiphonon peaks. To identify the nature of the transition for CdSe nanocrystals (NC), polarization anisotropy values were obtained. We suppose that carrier relaxation mechanism consists of two major parts. The first one is related to gradual relaxation with emission from intermediate states. The second one is associated with emission of LO-phonons. Analyzing resonantly excited PL spectra, we can separate contributions from these two mechanisms.