Dependency of Plasmonic Enhancement on the Refractive Index of the Dielectric Bottom Layer of Ag Nanoparticles

We investigated the dependency of plasmon-enhanced luminescence on the refractive index of a dielectric substrate of Ag nanoparticles. We used silicon dioxide (n=1.456) and indium tin oxide (n=1.8) as bottom layers for Ag nanoparticles. Due to the extinction spectra of Ag nanoparticles on substrates with high refractive indexes, the localized surface plasmon band moved toward a longer wavelength. Asymmetric ratios for probing plasmon effects can increase in proportion to the extinction of Ag nanoparticles. Adjusting the dielectric medium connected to the Ag nanoparticles, the increase of the extinction and the asymmetric ratios, led to the enhancement of the emission intensities from the Eu³⁺ ions.