Surface Plasmon-Mediated Light Emission from Dye Layer in Reverse Attenuated Total Reflection Geometry

Photoluminescence from a tris(8-hydroxyquinoline) aluminum (Alq 3 ) thin layer placed at various distances from a Ag thin film with the aid of a spacer layer was studied in a reverse attenuated total reflection geometry using a glass prism. Comparative studies of photoluminescence intensities and decay curves were performed for both the light emission into the free space and that into the prism. The prism-side emission, which arises via excitation and de-excitation of surface plasmon modes, showed spacer thickness dependence much different from that of the free-space emission. From a comparison with theoretical calculations, the optimum spacer thickness for the intensity of surface plasmon-mediated light emission was attributed to the optimum condition for surface plasmon excitation. The present experimental and theoretical results offer a guide to optimizing optical devices that utilize the surface plasmon-mediated light emission.