Regensburg 2010 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 17: Anomalous Transport I (joint BP, DY)

BP 17.6: Vortrag

Mittwoch, 24. März 2010, 10:45–11:00, H38

Anomalous transport in a medium subjected to phase transition — Daria Kondrashova, Jörg Kärger, and •Rustem Valiullin — Deprtment of Interface Physics, University of Leipzig, Leipzig, Germany

Diffusion in spatial structures created via invasion percolation may naturally exhibit anomalous properties. It is now becoming evident that phase transitions occurring in heterogeneous media, may also be described using the concept of invasion percolation [1]. Hence, transport properties of tracer particles in media subjected to phase changes can strongly be affected by the latter process, including conditions giving rise to anomalous transport patterns. In this work, we experimentally demonstrate that such fractal-like structures are developing during freezing and melting transitions of liquids in disordered mesoporous matrices. We show that the effective self-diffusivity in the pore space, occupied by the liquid phase at a given fraction, depends on a particular configuration of the frozen phase [2]. Interestingly, by using a porous material with tubular pore morphology, we were able to relate the phase transition kinetics to the propagation of the liquid-solid interfaces in the pores. Depending on temperature, this propagation itself is found to exhibit a spectrum of behavior from diffusive to anomalous. The data obtained may have implications for understanding anomalous transport in bio-systems such as lipid membranes.

1. Page, J. H., J. Liu, B. Abeles, H. W. Deckman and D. A. Weitz, Phys. Rev. Lett., 71, 1216 (1993). 2. Dvoyashkin, M., A. Khokhlov, R. Valiullin and J. Kärger, J. Chem. Phys., 129, 154702 (2008).