Dresden 2011 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 38: Poster: Colloids and Complex Liquids
CPP 38.26: Poster
Wednesday, March 16, 2011, 17:00–19:00, P2
Coupled colloidal particles out of equilibrium — •Carmen Groben1, Valentin Blickle1, Jakob Mehl1, and Clemens Bechinger1,2 — 12. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart — 2Max-Planck-Institut für Metallforschung, Heisenbergstrasse 3, 70569 Stuttgart
During the last two decades, there has been considerable progress in the understanding of thermodynamic processes in microscopic systems, where thermal fluctuations cannot be neglected. In this novel field of microscopic thermodynamics, experiments using single colloidal particles play an essential role, since there the phase-space trajectory can be directly observed optically.
To analyse more realistic situations, we extend a well-established single particle technique to study multiparticle nonequilibrium systems. Using rotating laser tweezers, we create two independent nonequilibrium steady states (NESS). Each NESS consists of a single superparamagnetic colloidal particle circulating in a three-dimensional toroidal laser trap. When magnetizing the particles by an external magnetic field, we induce a magnetic dipole-dipole interaction and therefore the coupling between the two NESS becomes adjustable. Depending on the driving forces and the magnetic coupling, we observe large differences in the trajectories of the particles. In our analysis we focus on the effective diffusion coefficient, which exhibits a maximum as a function of the coupling strength.