Observation of three electronic transitions in Cd(S,Se) nanocrystals by modulation spectroscopy

We report absorption and electromodulated transmission spectra for a series of CdS 0.44Se 0.56 nanoparticle/glass composites in which the average particle radius was varied from less than 2 nm to more than 6 nm by thermal treatment. We observe at least three distinct modulation peaks which shift with particle size. Tow of these peaks have been previously identified but we believe that the third is a new observation in electromodulation spectroscopy. We discuss the size-dependence of the energy, spectral shape, and magnitude of these modulation peaks.