Optical properties of square lattices of gold nanoparticles

We reanalyse optical measurements on two-dimensional lattices of ultrafine gold particles, produced by electron beam lithography. The spectra exhibit a distinct absorption peak due to the localized plasma resonance of the con duction electrons in the particles. The theoretical modeling used rigorous solutions, in the long-wavelength limit, for the polarizability of oblate s pheroids and truncated spheres on a substrate. The dipole-dipole interactio ns between the particles in the square lattice were taken into account. We find good agreement between experimental and theoretical absorption peak po sitions for the case of oblate spheroids, but not for truncated spheres. Pe ak widths and minimum transmittances also show satisfactory agreement with theory. (C)1999 Acta Metallurgica Inc.