Regensburg 2013 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 35: Brownian Motion and Transport
DY 35.6: Vortrag
Freitag, 15. März 2013, 10:45–11:00, H48
Collective particle dynamics crossing the freezing transition — •Markus Franke1, Sebastian Golde1,2, and Hans Joachim Schöpe1,3 — 1Johannes Gutenberg-Universität, Institut für Physik, Staudingerweg 7, 55128 Mainz, Germany — 2Graduate School Material Science in Mainz, Staudinger Weg 9, 55128 Mainz, Germany — 3Max-Planck-Institut für Polymerforschung, Postfach 3148, 55021 Mainz, Germany
We studied the collective particle dynamics in a hard sphere colloidal modell system of highly cross-linked polystyrene (PS) microgel particles dispersed in the good solvent 2-ethylnaphthalene. We determined the dynamics of the colloidal fluid around the main structure factor peak (1.7<qR<5) over a wide concentration range crossing the freezing transition point using dynamic light scattering. This gives access to the intermediate scattering function (ISF) which measures particle number density fluctuations or collecitve particle dynamics respectively. Further analyzation of the ISF dynamics shows that there is a significant difference in the relaxation mechanism of the collective density fluctuations of a fluid in the stable state and in the metastable state. In the nonequilibrium state the dynamics becomes heterogeneous in space and time. Once crossing the freezing point the fluid seperates in two fractions: One shows the dynamic signature of an equilibrium fluid and one displays an unequlibrium collective mode.