16 June 2004 Spectroscopy and dynamics of GaSe nanoparticles and nanoparticle aggregates
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The spectroscopic characteristics of GaSe nanoparticle aggregates are reported. We find that the lowest energy absorption band shifts slightly to the red and sharpens, while the next band shifts to the blue as the concentration is increased. The spectral changes are reversible and are interpreted in terms of the particles forming strongly interacting aggregates in high concentration, room temperature solutions. The absorption spectra can be semiquantitatively modeled in terms of the lowest two transitions observed in bulk GaSe, quantum confinement effects and dipolar coupling between excited state monomers. From these calculations, the lowest excited state interparticle coupling is estimated to be about -250 cm-1. Polydisperse samples have larger energy differences but comparable couplings between adjacent particles in the aggregates. As a result, the spectroscopic effects of aggregation are less pronounced in these samples. The nanoparticle aggregate spectra are reminiscent of J-aggregate spectra of organic dyes.
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David F. Kelley, David F. Kelley, Haohua Tu, Haohua Tu, Shuming Yang, Shuming Yang, Viktor Chikan, Viktor Chikan, } "Spectroscopy and dynamics of GaSe nanoparticles and nanoparticle aggregates", Proc. SPIE 5352, Ultrafast Phenomena in Semiconductors and Nanostructure Materials VIII, (16 June 2004); doi: 10.1117/12.531337; https://doi.org/10.1117/12.531337

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