Microbeam grazing incidence small angle X-ray scattering -: a new method to investigate heterogeneous thin films and multilayers

The combination of the ID13/ESRF micrometer-sized X-ray beam with the reflection geometry allowed to establish a new scattering method for investigating laterally patterned heterogeneous multilayers and interfaces. This new method-called microbeam grazing incidence small angle X-ray scattering (muGISAXS)-has been applied to a novel gradient multilayer of self-assembled nanometer-sized noble metal clusters on top of a polymer layer, being of significant importance for many technological applications, including biorecognitive sensoring. The new feature of using a 5 mum X-ray beam allows to characterize laterally heterogeneous samples on two length scales, induced by the small beamsize and reciprocal space resolution. From the two-dimensional muGISAXS patterns the three-dimensional structure and morphology of the gradient of gold (An) clusters was reconstructed using detailed model simulations. Though being a highly complex sample, it turned out that the gradient is characterized by a single parameter, namely the cluster height. Atomic force microscopy (AFM) and optical absorption spectra provide supplementary information and help to enlighten the structure of evaporated gold clusters on polymer layers. (C) 2004 Published by Elsevier B.V.