Adsorption of dye molecules on metallic nanoparticles: Unraveling the origins of the modified spectral absorption

Abstract

The enhanced optical response of molecules in the vicinity of metallic nanoparticle is the basis for many surface enhanced spectroscopies and of interest to the field of plasmonics. However, the mechanisms behind the enhancement are still a matter of debate because of the interplay between electromagnetic and chemical effects, which complicates the interpretation of spectral changes. Our ability to measure the surface absorption of dyes from very low coverage to high coverage allows us to identify the con- tribution of each effect (dye-dye interaction and dye-particle interaction) to the spectral modifications. In the course of this investigation, we also measured the adsorption isotherms of dyes in the presence of halide ions, which provides a detailed insight into the adsorption process on silver colloids.