Optical Scattering by Dense Disordered Metal Nanoparticle Arrays

We address the optical properties of dense disordered yet well-separated metal nanoparticle arrays produced by physical vapor deposition through anodized aluminum oxide membrane masks. Using variations in synthesis parameters, the particle diameters vary from 14 to 50 nm and average center separation from 45 to 112 nm. Ag nanoparticle arrays with no long-range periodicity exhibit apparently random formation of high-intensity depolarized regions relative to orientation of incident electric field. We analyze this behavior numerically using coupled dipole model and explain the contrast formation in recorded scattering images.