Size dependence of exciton fine structure in CdSe quantum dots

We use photoluminescence excitation and fluorescence line narrowing spectroscopies to examine structure observed in the band-edge absorption feature of CdSe quantum dots. We study eight samples ranging from similar to 15 to similar to 50 Angstrom in radius to probe the size dependence of this structure. We compare our results with recent theories, which predict band-edge exciton splittings in CdSe dots due to their internal crystal structure, non-spherical shape, and the exchange interaction between the electron and hole. We find reasonable agreement between our data and theory, supporting the observation of exciton fine structure.