Optical absorption properties of Ag/SiO₂composite films induced by gamma irradiation

Abstract

Mesoporous SiO2 composite films with small Ag particles or clusters dispersed in them were prepared by a new method: first the matrix SiO2 films were prepared by the sol–gel process combined with the dip-coating technique; then they were soaked in AgNO3 solutions; this was followed by irradiation with γ-rays at room temperature and ambient pressure. The structure of these films was examined by high-resolution transmission electron microscopy, and their optical absorption spectra were examined. It has been shown that the Ag particles grown within the porous SiO2 films are very small and are highly dispersed. On increasing the soaking concentration and subjecting the samples to an additional annealing, a different peak-shift effect for the surface plasmon resonance was observed in the optical absorption measurement. Possible mechanisms of this behaviour are discussed in this paper.