Screening Of Longitudinal Optical Phonons In Cdsse Nanocrystals By Photoexcited Carriers

The Raman spectra of a commercial Coming glass filter containing CdSSe nanocrystals have been found to be modified by increasing photoexcitation via picosecond laser pulses as a result of athermal effects. The observed effects have been explained semi-quantitatively by the screening of longitudinal optical phonons by the electronic transitions of one photoexcited carrier per nanocrystal.