Near-Field Probing Surface Plasmon Enhancement Effect on Two-Photon Emission

A photon scanning tunneling microscope is employed to probe the surface-plasmon-induced local field enhancement effect on two-photon fluorescence from organic nanoparticles adsorbed on silver surface. A size dependence of fluorescence enhancement and photodecomposition is observed, which results from the competition between the surface-plasmon-enhanced two-photon fluorescence and the nonradiative energy transfer from the excited dye molecules to the silver surface.