Modeling of core-shell silver nanoparticles in nanostructured sol-gel thin films

摘要

Silver nanoparticles were obtained by UV radiation of silica films containing Ag+ ions. 2d-hexagonal nanostructured sol-gel thin films were prepared by dip-coating method using the non-ionic diblock copolymer Brij58 to produce channels into the film, which house the silver nanoparticles. An absorption band located at 438 nm was detected; it corresponds to the surface plasmon resonance. High resolution transmission electronic microscopy measurements show core-shell structures of silver-silver oxide nanoparticles in these sol-gel silica films. These optical properties were modeled and well fitted with the Gans theory considering refractive index higher than the one coming from host matrix. This index is explained because the silver oxide shell modifies the local surrounding medium of the metallic nanoparticles and therefore plays an important role in the optical properties of the films.