Plasmon-Induced Modification of Fluorescent Thin Film Emission Nearby Gold Nanoparticle Monolayers

When placed in the vicinity of metal nanoparticles, fluorophore molecules can have their fluorescence intensity enhanced. In order to engineer highly fluorescent thin films, surface plasmon enhancement fluorescence was studied on macroscopic systems composed of gold nanoparticles deposited on a substrate and coated by a dye-containing polymer film. We developed a simple method based on surface silanization to get a good dispersion of up to 100 nm gold nanoparticles on a substrate. While controlling the nanoparticle size and the fluorophore concentration, we measured the fluorescence enhancement factors of systems doped with dyes possessing different quantum yields. We evidenced experimentally that a fluorescence enhancement factor of 4 could be reached for a low-quantum yield dye and that the fluorophore quantum yield affects significantly the enhancement factor. We then discussed how our experimental results agree with previously developed models.