Lasers And Plasmonics: Spr Measurements Of Metal Thin Films, Clusters And Bio-Layers

An extensive research has been carried out in synthesizing and characterizing single and double layer metal thin films of different thicknesses including ultrathin films. We discuss the experimental data of surface plasmon resonance (SPR) occurring at the interface between air, single and bimetallic thin layers of gold (Au) and silver (Ag) prepared on glass substrates. The bilayer configuration allowed for the measurements of the optical constants of metallic films that are ultra thin; e. g., below 10 nm of thickness since SPR modes on such thin films in a single layer configuration are shallow. In addition, using SPR technique, the optical constants of a natural biological thin layer (Allium cepa) is also estimated. Thickness and refractive index of metallic films were determined by matching experimental SPR curves to the theoretical ones. Thickness and roughness of the films were also measured by atomic force microscopy. The results obtained by experimental measurements are in good agreement with AFM analysis. It is estimated that the value of the real part of the dielectric constant of an onion epidermis is existing between the dielectric constants of water and air.