Ion beam shaping of Au nanoparticles prepared by micellar technique

Abstract

Irradiation-induced burrowing and ion-induced shaping effects of Au nanoparticles are investigated. Hexagonally arranged Au nanoparticles prepared by micellar technique with diameter ~10 nm and inter-particle distance of about 80 nm were sequentially irradiated with 200 keV Ar+ ions to fluences of 5×1015 ions/cm2. Irradiation with Argon ions causes sinking of the Au nanoparticles into the subjacent SiO2 layer due to capillary driving forces related to specific wetting conditions while the spherical shape is conserved. Subsequent irradiation with 54 MeV Ag8+ swift heavy ions of these spherical Au nanoparticles confined within a silica matrix shapes them into prolate nanorods and nanowires whose principal axes are aligned along the beam direction. Above a threshold fluence two deformation regimes have been observed. For relatively low fluences Au nanoparticles elongate into nanorods depending on their volume. For high fluences, the formation of nanowires is observed provided that the inter-particle distance is short enough to allow for an efficient mass transport through the silica matrix.