Diffraction from Arrays of Plasmonic Nanoparticles with Short-Range Lateral Order

Artikel i vetenskaplig tidskrift, 2012

We have measured the angular distribution of light scattered off 2D plasmonic Al nanoparticle ensembles. We created.. these samples with disk-like nanoparticles, 175 and 500 nm in diameter, respectively, using hole-mask colloidal lithography and electron beam lithography. The nanoparticle arrangements In the samples display the Short-range order (but no long-range order) characteristic for an ensemble formed by random sequential adsorption. As a consequence of this, the ensemble scattering patterns can be quantitatively well described by combining the single-particle scattering pattern with a static structure factor that carries information about the diffraction effects caused by the short-range order of the ensemble. We also performed sensing experiments in which we monitored changes in the angle-resolved scattering intensity for a fixed wavelength as a function of the thickness of an ultrathin SiO2 coating covering the Al nanoparticles. The data show that the angle and strength of the main diffraction peak vary linearly, with SiO2 coating thickness In the range 1.5-4.5 nm and suggest that measurements of the scattering profile could be a competitive alternative to traditional transmission measurements in terms of sensitivity.