Irregular, nanostructured superhydrophobic surfaces: Local wetting and slippage monitored by fluorescence correlation spectroscopy

In applications superhydrophobic surfaces are often irregular and nanostructured. On such a surface, it has been found that only a part of the surface is homogeneously wetted, i.e. wetting and slippage corresponding to that of a regularly structured surface. On the remaining part, large air inclusions occurred that possess a comparatively large slip length. In order to measure the velocity profile at distances below 1\textmu{}m close to the surface, an enhanced evaluation method for fluorescence correlation spectroscopy is developed in this work.