Berlin 2008 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 4: Colloidal Fluids

CPP 4.1: Vortrag

Montag, 25. Februar 2008, 14:30–14:45, C 264

Lateral critical Casimir forces between colloids and chemically patterned substrates — •Florian Soyka, Christopher Hertlein, Laurent Helden, and Clemens Bechinger — Universität Stuttgart, 2. Physikalisches Institut, Pfaffenwaldring 57, 70569 Stuttgart

The confinement of critical fluctuations in binary liquid mixtures near the critical temperature leads to so-called critical Casimir forces. Depending on whether the adsorption preference of the confining walls for one of the two mixture's components is identical or not, the force between the walls is either attractive or repulsive. In our experiments, we investigate the interaction between colloidal particles and a flat wall in a critical water - 2,6 lutidine mixture. As substrates we used glass surfaces which were chemically patterned on a micron-scale leading to a laterally periodic modulation of the substrate's adsorption preference for water and lutidine. When approaching the critical temperature, we observe strong lateral forces acting on the colloidal particles above such substrates which are attributed to critical Casimir forces. Apart from the fundamental importance of such interactions, lateral critical Casimir forces may be also utilized to create ordered arrays of colloidal particles which are important e.g. in photonic applications.