Self-organized ion-beam synthesis of nanowires with broadband plasmonic functionality

The controlled production of nanostructures endowed with well-selected shapes and reduced dimensionality represents a multidisciplinary key activity in nanotechnology. In particular, a great effort is currently oriented at the development of metal nanoparticle arrays in order to exploit the strong field-enhancement effects associated with the excitation of localized surface plasmon resonances. Here we demonstrate that ion-beam sputtering can be successfully employed to convert a polycrystalline metal film into a disconnected array of nanowires supported on a flat dielectric substrate. The nanowire arrays exhibit spectrally selective dichroic absorption due to the excitation of localized plasmon oscillations. The possibility to tailor the broadband plasmonic response has been demonstrated by finely tuning the morphological parameters of the arrays.