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Femtosecond pump-probe spectroscopy, in the visible spectral range, is used to study fast processes after photoexcitation in quantum confined wurtzite CdSe core and CdSe∕ CdS∕ ZnS core/shell nanorods. Effective-mass theory is applied to assign the energy levels in linear absorption spectra. Sequential bleaching of the excitonic states and photoinduced absorption are observed in the transmission difference spectra. A strong difference was found between the core and core/shell samples. In fact, in the transient transmission difference spectra, the decay time of the higher energy states is faster in the core than in the core/shell samples (200 fs versus 500 fs), due to the trapping in the unpassivated surface states of the bare core. Stimulated emission (SE) has been achieved in CdSe core and core/shell quantum rods at room temperature. As a striking feature, the SE is sustained for a shorter time in the core/shell …
American Physical Society
Publication date: 
30 Sep 2005

Arianna Cretí, Marco Anni, Margherita Zavelani Rossi, Guglielmo Lanzani, Gabriella Leo, Fabio Della Sala, Liberato Manna, Mauro Lomascolo

Biblio References: 
Volume: 72 Issue: 12 Pages: 125346
Physical Review B