Core-satellite metallic nanoclusters in silica obtained by multiple ion beam processing

Ion irradiation has been used to transform spherical bimetallic AuAg nanocluster embedded in silica in a more complex structure made of a central cluster surrounded by a halo of smaller satellite nanoclusters, whose composition, size and distance from the central cluster can be tailored by controlling the irradiation parameters. This peculiar topology produces a red-shift of the surface plasma resonance of the composite through the electromagnetic coupling between the central cluster and the satellites. A calculation of the local field properties of the investigated systems within the fully-interacting generalized Mie theory showed that the satellite topology produces large local field enhancements around the central cluster.