Diffraction from arrays of plasmonic nanoparticles with short-range lateral order.
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 1.5-4.5 nm and suggest that measurements of the scattering profile could be a competitive alternative to traditional transmission measurements in terms of sensitivity.
Department of Applied Physics, Chalmers University of Technology, SE-412 96 Göteborg, Sweden. markusschwind@gmail.com
Markus
M
Schwind
Vladimir D
VD
Miljković
Michael
M
Zäch
Viktoria
V
Gusak
Mikael
M
Käll
Igor
I
Zorić
Peter
P
Johansson
D008027:Light; D008422:Materials Testing; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D012031:Refractometry / Q000379:methods*; D012542:Scattering, Radiation; D020349:Surface Plasmon Resonance / Q000379:methods*