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Graduate Thesis Defense on April 30

Apr 21, 2014

THESIS DEFENSE
Speaker: Stephen Fatokun
Date: Wednesday, April 30, 2013
Time: 4:00 pm
Room: 336 Currens Hall

Effect of ZnSe and CdSe Nanoparticles on the Fluorescence and Optical Band Gap of Sm3+ doped Lead Borate Glasses

Abstract:


We prepared a series of Sm-doped lead borate (PbO-B2O3) glasses containing zinc selenide (ZnSe) and cadmium selenide (CdSe) nanoparticles (NPs) and studied the Sm3+ fluorescence and optical band gap by varying the glass composition and size of the NPs. Transmission electron microscopy characterization showed that CdSe NPs are considerably larger than ZnSe NPs. The presence of CdSe NPs is seen to produce the greatest influence on the fluorescence intensity ratio. Detailed analysis of the fundamental absorption edge in the optical absorption spectra was carried out using the Mott-Davis model. For samples without the NPs, the optical band gap decreases with increasing PbO concentration. The presence of ZnSe NPs shows a similar trend. The introduction of CdSe NPs, however, shows an increase in the optical band gap with increase in PbO content. Our results indicate that CdSe NPs show markedly different effect on the Sm3+ fluorescence and the optical absorption of lead borate glasses compared to ZnSe NPs. The size difference between ZnSe and CdSe NPs can produce significant differences in their electronic properties which in turn could affect their interaction with the rare earth ion and the glass matrix.

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