Effects of helium ion bombardment on metallic gold and iridium thin films

Single layer mirrors have been prepared by evaporating gold and iridium on silicon substrates. The samples have been exposed to 4 keV He + ion flux at different total fluences, simulating the effect of solar wind ions on optical coatings. We show that the ion implantation significantly affects the optical characteristics of the metallic films. The phenomena are explained and modeled also considering the related material modifications observed with chemical and morphological analysis.