Electron shuttling across the interface of CdSe nanoparticles monitored by femtosecond laser spectroscopy

Femtosecond laser spectroscopy is used in studying the formation and decay of the optical hole (bleach) for 4 nm CdSe nanoparticles (NPs) with 1,4-benzoquinone and 1,2-naphthoquionone as the adsorbed electron acceptors. The growth and decay of the reduced electron acceptors formed after interfacial electron transfer from the CdSe NPs were also examined. Results indicated that the electron transfer from the NPs to the quinone occurs after thermalization of the excited hot electrons based on the ultrashort rise times of the bleach at the band-gap energy. The decay times for the electron acceptor radical anions is similar to the CdSe bleach recovery time of 3 ps.