Optical properties of Rhodamine B and Rhodamine 6G on silver surfaces

The transmission spectra of Rhodamine B and Rhodamine 6G dyes coated on silver island films for various thickness were recorded. A strong coupling between the silver particle plasma resonance and the dye molecules is observed. The absorption of dye molecules increases when the absorption band of individual dyes and silver particles overlaps. In higher silver film thicknesses, transmission increases. The theoretical calculation using Maxwell-Garnett theory and Wang and Kerker’s results qualitatively supports the observed phenomenon. A red shift in the absorption peak of dyes on silver surfaces in comparison to solution phase absorption peak indicates photobleaching.