DETERMINATION OF MICROMETER LENGTH SCALES WITH AN X-RAY REFLECTION ULTRA SMALL-ANGLE SCATTERING SET-UP

We show that the accessible range of length scales of structures deduc ed with ultra small-angle scattering (USAX) experiments can be enlarge d by more than one order of magnitude in reflection geometry set-ups. From the analysis of the diffuse scattering without further model assu mptions the length scale of the structures is determinable. The method is illustrated by an example of thin blend films of deuterated polyst yrene (dPS) and poly-paramethylstyrene (PpMS) where um-structures are recovered. The results are compared to atomic-force microscopy measure ments. For a further comparison, USAX data of a water-based dispersion of polymer particles are presented. They illustrate the resolvable le ngth scale of the conventional transmission geometry.