Regensburg 2013 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 33: Poster: Charged Soft Matter

CPP 33.3: Poster

Wednesday, March 13, 2013, 16:30–18:30, Poster C

Using Super-Heterodyne Laser Doppler Velocimetry for measurements in low concentration suspensions of charged colloids — •Bastian Sieber and Thomas Palberg — Institut für Physik, Johannes Gutenberg Universität Mainz, Staudingerweg 7, D 55122 Mainz

Soft condensed matter is characterized both by its softness and an internal structure on a mesoscopic scale. This allows convenient optical access to system structure and dynamics in equilibrium. Among the various soft matter systems, charge stabilized colloidal dispersions have gained recognition as tremendously useful model condensed matter systems because of their structural ordering and rich phase behaviour. Experimentally, we studied electrokinetic flow in closed cells with electroosmotic solvent flow. Super heterodyning renders the data of interest free of homodyne contributions and low frequency noise. We used this method to study an aqueous charged sphere suspension driven under the influence of an external electric field. Measurements have been performed on suspensions of various concentrations by diluting the suspension further between measurements to reach very low concentrations in the process. Preliminary results show an increase in the electro-osmotic velocity with lower concentration while the electro-phoretic velocity is decreasing. Further data on this topic will be provided and discussed.