SURFACE-PLASMON ENERGY GAPS AND PHOTOLUMINESCENCE

Excited dye molecules on a metallic grating can relax by generating su rface plasmon polaritons (SPP's). These SPP's can scatter from the gra ting reradiating their energy as photons. For dye molecules in contact with the metal, light radiated by SPP's dominates the optical emissio n from the system. If the wavelength of the SPP is equal to half the p itch of the grating then the mode can Bragg reflect from the surface a nd an energy gap opens up in the SPP dispersion. This paper examines t he effect that such an energy gap has on the emission properties of th e dye. Experimentally it is found that the SPP energy gap significantl y inhibits emission from the system. Numerical modeling is used to sho w that the modified emission spectrum is determined by the wavelength dependence of the density of available SPP states.