Berlin 2018 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 35: Microswimmers I (joint session DY/BP/CPP)
CPP 35.1: Vortrag
Dienstag, 13. März 2018, 14:00–14:15, BH-N 243
Active colloidal propulsion over a crystalline surface — Udit Choudhury1, •Arthur Straube2, Peer Fischer1, John Gibbs3, and Felix Höfling2 — 1Max-Planck-Institut für Intelligente Systeme, Stuttgart, Germany — 2Freie Universität Berlin, Institute of Mathematics, Berlin, Germany — 3Department of Physics and Astronomy, Northern Arizona University, Flagstaff, USA
We study both experimentally and theoretically the dynamics of chemically self-propelled Janus colloids moving atop a two-dimensional (2d) crystalline surface [1]. The surface is a hexagonal close-packed monolayer of colloidal particles of the same size as the mobile one. The dynamics of the self-propelled colloid reflects the competition between hindered diffusion due to the periodic surface and enhanced diffusion due to active motion, which can be tuned by changing the concentration of a chemical fuel. Our experimental data for the mean-square displacements (MSDs) are consistent with a Langevin model for the effectively 2d translational motion of an active Brownian particle in a periodic potential, combining the confining effects of gravity and the crystalline surface with the free rotational diffusion of the colloid. Approximate analytical predictions are made for the MSD describing the crossover from free Brownian motion at short times to active diffusion at long times. The results are in semi-quantitative agreement with numerical results of a refined Langevin model that treats translational and rotational degrees of freedom on the same footing.
[1] U. Choudhury, A. V. Straube, P. Fischer, J. G. Gibbs, F. Höfling, New J. Phys. (2017), doi: 10.1088/1367-2630/aa9b4b