Energy shift of photoemission spectra for organics-passivated CdSe nanoparticles: The final-state effect

Size-dependent energy shift of photoemission spectra with respect to bulk sample has been examined for colloidally prepared CdSe nanoparticles with a series of particle sizes. The core-level shifts are well described by a theoretical calculation based on a final-state effect model, whereas an additional initial-state effect due to quantum confinement is required to elucidate the valence-band edge shifts. The results indicate that the interaction between the photohole and the dielectric background in the final state has to be considered in photoemission measurements for organics-passivated nanoparticles. The calculated results in the literature appear to overestimate the initial-state effect compared to our experimental observation.