Optical resonances of gold nanoparticles on a gold surface: quantitative correlation of geometry and resonance wavelength

The optical resonance of gold nanoparticles placed at nanometre distances from a gold surface by means of a dielectric spacer was investigated. Different types of molecules, 2-aminoethanethiol and shape-persistent polyphenylene dendrimers were used as spacers and compared. Furthermore, the gold nanoparticle size and the ambient medium were varied. The influence of all these parameters on the resonance wavelength of the system was determined. Based on a simple analytical model, a quantitative analysis was developed and surprisingly good agreement of this model with our experiment without any adjustable parameters was found.