Investigations of heterogeneous diffusion based on the probability density of scaled squared displacements observed fr om single molecules in ultra-thin liquid films
Michael K. G. Bauer, Mario Heidernätsch, Daniela Täuber, Christian von Borczyskowski, Günter Radons · 2009
Diffusion processes in ultra-thin liquid films obse rved by video microscopy reveal a complex behavior. In contrast to homogeneous diffusion, dynamic and static heterogeneities are induced by layer transitions an d compartments with differing diffusion coefficients, respectively. The objective of this research is the detection and distinction of such heterogeneities as well as an a nalysis of the underlying processes. Hence, a new method is proposed establishing a prob ability density of scaled squared displacements. This probability density allows for a simple and well-defined calculation of time-dependent diffusion coefficients and its fl uctuations. Furthermore, by simulating a heterogeneous diffusion process these results are verified and compared to mean square displacement calculations. By means of the simulate d probability density data, their