Structure determination in thin film geometry using grazing incidence small-angle scattering

In the thin film geometry reflectivity measurements are a widespread technique to determine the density profile perpendicular to the sample surface. From off-specular scattering additional information about the surface roughness, lateral correlations, sizes and shapes of objects (particles, nanostructures) positioned on top of the surface or in a surface near region are accessible. The use of a grazing incidence geometry enhances the surface sensitivity. Grazing incidence small-angle scattering (GISAS) overcomes the limitations of conventional smallangle scattering with respect to extremely small sample volumes in the thin film geometry. Although real space analysis techniques such as scanning force microscopy (SFM) enable an easy access to surface structures, reciprocal space analysis techniques such as GISAS with X-Rays and neutrons include several advantages: 1. scattering yields averaged statistical information over the whole illuminated sample surface; 2. scattering is applicable in numerous environments such as ultra-high vacuum, different gas atmospheres and in liquids; 3. scattering can be performed in real time accessing kinetics phenomena; and 4. using the variable probed depth as function of the incidence angle, scattering offers the opportunity to characterize buried lateral structures destruction-free as well. By the use of either X-Rays or neutrons the scattering contrast in a system can be reversed. To demonstrate the possibilities of GISAS several different examples of thin polymer films are presented.