Investigations of the electronic structure of nanoscaled gold-colloids in sol-gel-coatings

The electronic structure of nano-scaled Au-colloids embedded in thin glass-like sol—gel coatings on glass substrates was investigated by small-angle X-ray scattering (SAXS) in grazing incidence and by UV-VIS spectroscopy as a function of the densification temperature of the coatings and of kind and concentration of the stabilizer used in the sol. Special interest was concentrated on the structure of the interface between matrix and colloids. It was found that the structure of this interface changes with the preparation of the coatings. Depending on densification temperature and stabilizer, it was observed that the structure of the surface of the colloids or the interface region between matrix and colloids is changing continuously from a structure similar to a fractal surface to a sharp phase boundary. Further densification leads partially to a ‘fuzzy’ colloid surface which is supposed to be due to the formation of a highly densified shell around the colloids caused by the ligands.