Absorption and photoluminescence properties of silver clusters in SiO_2 matrix

摘要

Absorption and luminescence properties of silver nanoclusters embedded in SiO_2 matrixes were studied experimentally. Thin SiO_2 films with different amount of silver were produced by co-deposition of Ag and SiO_2 onto the silica substrates in vacuum. The thus obtained films possess three peaks in absorption spectra at 297, 329 and 401 nm and two peaks in luminescence spectra at about 500 and 650 nm. We ascribed these spectral features to silver nanoclusters of different sizes that present in the film. Thermal annealing transforms both absorption and emission spectra of the films. Lager clusters that are formed after annealing possess one absorption band at 350-450 nm and one luminescence band at 510 nm. The luminescence was observed only in samples with the silver content of less than 2.2%. Quenching of the luminescence in samples with higher concentration of silver is due to the presence of larger particles with plasmonic properties.