Interaction between clusters in ion implanted and ion beam mixed SiO 2:Ag films

Spectra of optical extinction in the visible range for SiO 2:Ag colloid films prepared by ion implantation and ion beam mixing are compared to calculations for isolated clusters and for interacting clusters in an effective medium. Whereas for low metal concentrations the shape of the spectra is determined by the cluster size, at higher concentrations it largely depends on their mutual interaction. This interaction induces a broadening of the resonance in implantated films and on the contrary a narrowing in ion beam mixed films. The difference is ascribed to a particular arrangement of the clusters, with a bimodal size distribution, in the latter films.