Enhancement of Dye Fluorescence by Gold Nanoparticles: Analysis of Particle Size Dependence

Abstract
Rose Bengal was spun on spherical gold nanoparticles immobilized on a quartz plate by a silane coupling agent. The enhancement of the dye fluorescence was studied by changing the diameter of the gold nanoparticles from 20 to 250 nm. A maximum enhancement of dye fluorescence was observed at a size of 100 nm. We found good agreement between the experimental result and the theoretical calculation. From the theoretical analysis it is suggested that the maximum enhancement is obtained when the incident light and fluorescence light are in optimum resonance with the surface plasmons in the gold nanoparticles. These results demonstrate that the control of particle size is extremely important to obtain an optimum enhancement of dye fluorescence caused by metal particles.