Optical characterization of CdSe nanocrystals

We have investigated the optical properties of CdSe nanocrystals by using the transmittance and photoluminescence spectroscopy. The samples used in the optical experiment are nanocrystals of cylindrical rods and spheres dispersed in toluene. The transition features in the photoluminescence spectra agree with the transition edges observed in the transmittance spectra. Theoretical models based on the effective mass approximation with infinite barriers were established for both types of nanocrystals. The calculated transition energies and oscillator strengths are compared with the observed spectral features. Improved models with the finite barrier and shallow potential step to account for the capping contribute to minor corrections of the order of thousandths.