Influence of metallic nanoparticles on up-conversion processes

Abstract : It is well known that Raman scattering and fluorescence can be enhanced by the presence of metallic nanoparticles. Here, we derive simple equations to analyze the influence of metallic nanoparticles on upconversion processes such as nonradiative energy transfer or excited state absorption. We compare the resulting expressions with the more familiar Raman and fluorescence cases and find significant differences. We use numerical simulations to calculate the upconverted signal enhancement achievable by means of metallic spheres of different radii and find particles of 100–400 nm radius at infrared frequencies to be favorable. We also discuss the considerable challenges involved in using metallic particles to enhance upconversion for solar energy.