Berlin 2012 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 29: Posters II

DY 29.19: Poster

Thursday, March 29, 2012, 17:00–19:00, Poster A

Characterizing heterogeneous diffusion by the distribution of diffusivities — •Michael Bauer and Günter Radons — Chemnitz University of Technology, Germany

Heterogeneous diffusion processes arise in many physical and biological applications where the diffusive behavior changes during the motion. For instance, diffusion in ultra-thin liquid films is governed by layer-dependent diffusion coefficients and jumps between the liquid layers. The observation of individual tracers by single-particle tracking (SPT) allows for a characterization of such processes. Hence, we suggested to investigate the distribution of diffusivities and their dependence on the time lag between snapshots [1]. This analysis should be preferred to conventional methods such as mean-squared displacements which conceal the effects of inhomogeneities. We also studied the relation to ensemble-based measurements obtained from pulsed field gradient nuclear magnetic resonance (PFG NMR) and applied it to the two-region exchange model [2]. In our contribution we extend the investigations to systems in the presence of observation noise, which is of high relevance for experimental data. Moreover, our objective is to consider higher moments of the distribution of diffusivities and their dependence on the time lag, which characterizes the diffusivity as a fluctuating quantity along a trajectory.

[1]  M. Bauer et al., Diffus. Fundam. 11, 104 (2009)

[2]  M. Bauer et al., J. Chem. Phys. 135, 144118 (2011)