Diffraction from Arrays of Plasmonic Nanoparticles with Short-Range Lateral Order (original) (raw)
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 SiO 2 coating covering the Al nanoparticles. The data show that the angle and strength of the main diffraction peak vary linearly with SiO 2 coating thickness in the range 1.5À4.5 nm and suggest that measurements of the scattering profile could be a competitive alternative to traditional transmission measurements in terms of sensitivity.
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