Regensburg 2000 – scientific programme

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DY: Dynamik und Statistische Physik

DY 17: POSTER I

DY 17.30: Poster

Monday, March 27, 2000, 15:00–18:00, D

Mode Coupling Scheme for Colloidal Electrolyte Friction and Electrophoresis — •Markus Kollmann and Gerhard Nägele — Fakultät für Physik, Universität Konstanz, Postfach 5560, D-78457 Konstanz, Germany

Using a simplified mode-coupling-scheme for colloidal mixtures, we calculate the effect of mobile salt- and counterions on the tracer diffusion of a suspended colloidal macroion. In this scheme, direct potential forces and also the leading far-field hydrodynamic interactions (HI) between macroion and small ions are accounted for. The static correlation functions, which are needed as input, are treated in a first step within the Debye-Hückel approximation. In this way, analytical results are obtained for the long-time self-diffusion coefficient of the macroion as function of the electrolyte concentration and various electrolyteion mobilities. The exact Onsager limit is recovered for vanishing macroion radius and HI disregarded. In a second step, finite size effects of the electrolyte ions are accounted for. Additionally, we present results for the frequency-dependent macroion mobility. Our results are compared with experimental data on electrolyte friction and other existing theories.