8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

Wed 711:10-14:00P5.83Glass transition in charged colloidal suspensionsHerbert Kaiser, 1 Nicolai Saenger, 1 Matthias Fuchs, 1 and Georg Maret 11 University of Konstanz, Universitaetsstr. 10, 78464, Konstanz, GermanyThe transition from the liquid state to an amorphous state called ”glass” is still one of the problemswhere theories do not give a description for all the phenomena. The mode coupling theory (MCT)can qualitatevely predict many of the experimental findings and has so far been extensively testedfor colloidal systems, where particles interact as hard spheres. However, atomic glasses usuallyinvolve strongly repulsive interactions such as charged colloids in a solvent at very low ionicstrength, so that the charge is screened only at a distance substantially larger than the particlediameter. We use two different systems that fulfill these criteria. Micron size fluorescently labelledPMMA spheres in a CHB/Decalin solvent and polysterene particles of 50 to 250 nm in diameterin well deionized water. For the PMMA spheres we use confocal microscopy and can thereforeget the complete information of the particle positions. The PS particles are much smaller andstrong light scatterers and can be examined by diffusing wave spectroscopy (DWS), which stillgives many informations about the dynamics of the system. So far the experiments have shownthat large size and charge polydispersities are needed in order to prevent crystallization. But it ispossible to produce repulsive glasses at volume fractions lower than 10% and the dynamics of thesystem can be compared to results from the MCT.83