SAXS investigation of porous nanostructures

Fractal and aggregate structures of aerogels were investigated by small angle X-ray scattering in order to analyze the various evaluation methods of the SAXS data for porous nanostructures. Scattering data (SAXS, USAXS) for aerogels measured with laboratory equipment as well as synchrotron technique were interpreted in the terms of Guinier, Porod, Freltoft, Teixeira, and Emmerling theories. We modified the Freltoft fit in order to get information about the structure of elementary units. The performances of the evaluation programs were studied for different aerogels structures such as fractal of wide range, fractal of limited size, and aggregate systems. The evaluation of the scattering measurements resulted in fractal dimensions, sizes of the elementary units, sizes of the fractal domains or aggregates. Quality of the fits to SAXS data was characterized by a mathematical parameter and proved by TEM photography. TEM images confirmed the sizes of the elementary building units and clusters.