Silica-supported silver nanoparticles: tailoring of structure-property relationship

Silica-supported silver nanoparticles were obtained by RF-sputtering from Ar plasmas under soft synthesis conditions, with particular attention to the combined influence of RF-power and total pressure on the system composition, nanostructure, morphology and optical properties. In order to attain a thorough insight into the nucleation and growth phenomena of Ag nanoparticles on the silica substrate, several in-situ and ex-situ characterization techniques were used. In particular, a laser reflection interferometry system was employed for a real-time monitoring of the deposition process, providing useful and complementary information with respect to the other ex-situ techniques (x-ray photoelectron spectroscopy and x-ray excited Auger electron spectroscopy, glancing incidence x-ray diffraction, atomic force microscopy, optical absorption spectroscopy, and transmission electron microscopy). The above investigations evidenced the formation of silver-based nanosystems (average crystallite size < 10 nm), whose features (metal content, Ag particle size and shape, structure and optical properties) could be carefully tailored by moderate and controlled variations of the synthesis parameters.