The Effect of Oxidation on the Far-Field Scattering of Aluminium Patch Antennae from Visible to UV

In this paper we evaluate the effect of oxidation on the total power scattered in the far field by a 60nm radius Al sphere in the presence of a substrate comprised of either Al or silica (SiO2). Using an effective medium approach to model the Al particle with an outer layer of alumina (Al2O3), we find that the UV peak of total energy scattered in the far field shifts towards longer wavelengths for volume fractions of Al2O3 up to 20%. When particles with these volume fractions are held above an Al substrate, enhancement of two orders of magnitudes of the far-field power radiated by a dipole in the gap can be observed. For larger volume fractions of Al2O3, the total intensity of light scattered is significantly reduced.