SMALL-ANGLE X-RAY-SCATTERING EXPERIMENTS IN GRAZING-INCIDENCE ON SOL-GEL COATINGS CONTAINING NANO-SCALED COLLOIDS - A NEW TECHNIQUE FOR INVESTIGATING THIN COATINGS AND FILMS

Small-angle X-ray scattering (SAXS) is generally not applicable to thi n (similar to 1 mu m) films and coatings because of their weak scatter ing signal in conventional transmission experiments. This restriction can be overcome by working in grazing incidence, with an angle of inci dence ct slightly above the critical angle of total reflection phi(c), in order to augment the effective X-ray path in the sample. The possi bilities of this technique are demonstrated by preliminary results obt ained on glass-like sol-gel coatings containing nano-scaled gold collo ids. The scattering of the gold colloids was identified by variations of the X-ray energy near the absorption edge of gold (anomalous SAXS). It showed the theoretically predicted variation of intensity with ene rgy. The recorded scattering spectra were corrected for absorption and refraction effects, whose influences on the spectra are discussed. Ca lculated size distributions of the colloids from SAXS in grazing incid ence were compared with results from high-resolution transmission elec tron microscopy (HTEM) investigations and optical UV-visible spectrosc opy.