Regensburg 2010 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 1: Topical Session Glass Dynamics I

MM 1.3: Vortrag

Montag, 22. März 2010, 11:15–11:30, H16

Dynamics of colloidal suspensions in a modulated light field — •Cecile Dalle-Ferrier, Matthew Jenkins, and Stefan Egelhaaf — Lehrstuhl für Physik der weichen Materie, Heinrich Heine Universität, Düsseldorf, Deutschland

We experimentally investigated the structure and dynamics of an aqueous suspension of charged polystyrene beads in a modulated light field. The light field can be considered as an external 1D-periodically modulated potential, which has been shown to be a good model for the non-Gaussian dynamics in glassy systems of cage escape and subsequent recaging [1]. Our samples indeed showed glassy behaviour in the modulated light field, even in the case of dilute samples. Following the particles with microscopy, we find that the time-dependence of the mean-square displacement exhibits a plateau and the value of the non-gaussian parameter is non-zero. The height of the plateau and its extension in time, and more generally the dynamics of the particles, depend on the characteristics of the potential such as its amplitude and period. These results indicate that the application of a modulated light field to a colloidal suspension is a convenient tool to turn a liquid into a glass-like system. It offers extensive control of this transition through the parameters of the light field. We plan to use this model further to progress our understanding of the glass transition, in particular the characterization of glassy dynamics, including dynamical heterogeneities.

[1] B. Vorselaars et al., Non-Gaussian nature of glassy dynamics by cage to cage motion, Phys. Rev. E, 75, 011504 (2007)