Plasmonic Interaction Between Silver Nano-Cubes and a Silver Ground Plane Studied by Surface-Enhanced Raman Scattering

The plasmonic interaction between silver nano-cubes and a silver ground plane with and without a dielectric spacer is studied for surface-enhanced Raman scattering (SERS) for rhodamine 6G (R6G) molecules absorbed onto the silver nano-cubes. Experimental results show that the composite substrates made from silver nano-cubes and the silver ground plane produce a stronger SERS signal than by the cubes alone, due to the plasmonic interaction between the cubes and the film. Numerical simulation is used to verify the plasmonic enhancement of the composite substrate and is consistent with the experimental results. The lowest concentration of R6G molecules which can be detected with the composite substrate is about 10(-11) M with our setup.