Investigations of Static and Dynamic Heterogeneities in Ultra-Thin Liquid Films via Scaled Squared Displacements of Single Molecule Diffusion

1. Introduction For analyzing the mobility of diffusing molecules, single molecule experiments are well established. Experiments in ultra-thin liquid films revealed a heterogeneous behavior of diffusion [1], which could be explained by a layering of liquids at solid interfaces as reported in [2]. Consequently, a layer model with layer-dependent diffusion coefficient was developed. Layer transitions of the observed molecules induce dynamic heterogeneities in the projection of their diffusion. They are strongly dependent on the dwell times in the layers. Additionally, experimental observations and recent research [3] indicate an inhomogeneous layer on the substrate. This results in domains which influence the local diffusivity and lead to static heterogeneities in the observation. The objective of this research is an approach for the distinction between dynamic and static heterogeneities. Furthermore, a characterization of these heterogeneities should be achieved.