Berlin 2008 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

CPP: Fachverband Chemische Physik und Polymerphysik

CPP 32: Colloid Dynamics

CPP 32.3: Vortrag

Donnerstag, 28. Februar 2008, 11:45–12:00, C 264

Critical dynamics of ballistic and Brownian particles in a heterogeneous environment — •Felix Höfling, Tobias Munk, Erwin Frey, and Thomas Franosch — Arnold Sommerfeld Center for Theoretical Physics (ASC) and Center for NanoScience (CeNS), Department of Physics, Ludwig-Maximilians-Universität München, Theresienstraße 37, 80333 München

Transport of tagged ions, macromolecules, or nanoparticles in heterogeneous environments is strongly hindered by the presence of a variety of differently sized components. Three major transport phenomena are observed: normal diffusion, immobilization or localization, and anomalous transport. It will be shown that all aspects may be unified into the concept of transport in a disordered, heterogeneous medium with a percolation transition [1].

We have investigated Lorentz models with ballistic and Brownian tracer particles by means of large-scale computer simulations. It is demonstrated that in the immediate vicinity of the localization transition, universality holds at large time scales. The scaling function describing the crossover from anomalous transport to diffusive motion is found to vary extremely slowly and spans at least 5 decades in time. To extract the scaling function, one has to allow for the universal corrections to scaling. Our findings suggest that apparent power laws with varying exponents generically occur and dominate experimentally accessible time windows as soon as the heterogeneities cover a decade in length scale.

[1] Höfling, Franosch & Frey, Phys. Rev. Lett. 96, 165901 (2006)