INVESTIGATIONS OF THE ELECTRONIC-STRUCTURE OF NANOSCALED GOLD-COLLOIDS IN SOL-GEL-COATINGS

The electronic structure of nano-scaled Au-colloids embedded in thin g lass-like sol-gel coatings on glass substrates was investigated by sma ll-angle X-ray scattering (SAXS) in grazing incidence and by UV-VIS sp ectroscopy as a function of the densification temperature of the coati ngs and of kind and concentration of the stabilizer used in the sol. S pecial interest was concentrated on the structure of the interface bet ween matrix and colloids. It was found that the structure of this inte rface changes with the preparation of the coatings. Depending on densi fication temperature and stabilizer, it was observed that the structur e of the surface of the colloids or the interface region between matri x 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. (C) 1997 Elsevier Science B.V.