To explain the experimentally observed effect of silver nanoparticles on the fluorescence of organic dyes and the nonradiative intermolecular transfer of electronic excitation energy in multilayer nanostructures, the previously proposed theoretical model of plasmon resonance in spherical nanoparticles of metals was used. The rates of radiative and nonradiative (FRET) processes in film structures with Ag nanoparticles were calculated for fluorescein and rhodamine B molecules, as well as for two-component systems fluorescein-nile red (NR) and rhodamine B-NR. A version of the model was used that takes into account the effect of NPs on FRET between molecules, the radiative decay of donor and acceptor molecules, and the energy transfer from the dye to plasmonic nanoparticles. The calculation of the UDA rate for pairs with different energy transfer efficiency showed a greater increase in the UDA parameter for the fluorescein-nile red pair than for the rhodamine B-nile red pair. Estimation of the fluorescence enhancement factor of donor and energy acceptor molecules and the rate of energy transfer from the dye to silver NPs showed their insignificant contribution to the formation of the resulting energy transfer efficiency enhancement in the presence of plasmonic NPs. Keywords: energy transfer, silver nanoparticles, plasmon, model
The structure and optical properties of nanodots based on graphene oxide (GO) obtained by ablation by laser radiation with different wavelengths were studied. It was shown that after laser ablation, the average lateral size of GO sheets decreases from 820±120 nm to 204± 40 nm and 105± 23 nm for samples prepared at λgen=355 and 532 nm, respectively. In this case, a change in the intensities of the 2D and G bands was observed, which indicates a decrease in the number of layers in the GO sheets. The optical density of GO dispersions and the intensity of fluorescence depend on the ablation conditions. After ablation, the optical density of GO increased by ~ 13% for samples obtained at λgen=355 nm and by 20% for λgen=532 nm. The fluorescence intensity of GO ablated at λgen=532 nm increased by 57% relative to the value registered for GO before ablation. For 355 nm, the fluorescence intensity was changed by 7%. Keywords: graphene oxide, graphene dots, ablation, structure, optical properties.
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