Abstract
Colloidal solutions of Au/SiO2 core–shell nanoparticles (NPs) are synthesized. The diameters of Au core are 40nm, 60nm, 80nm and 110nm and the thickness of SiO2 shell is 20nm. The metal-enhanced fluorescence of CdTe quantum dots (QDs) in aqueous solutions is studied by mixing the Au/SiO2 NPs colloidal solutions with different concentrations. As the molar ratio of the Au/SiO2 NPs and the CdTe QDs increases, the fluorescence enhancement factor grows rapidly because of the plasmonic enhancement, and then a reduction of the enhancement factor is observed because of the absorption of Au/SiO2 NPs. The largest fluorescence enhancement factor of 8 is obtained at the optimal molar ratio, when the surface plasmon resonance of the Au/SiO2 NPs (60nm) matches the emission peak of the CdTe QDs. The results of our theoretical analysis support the experimental results.
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