Colloidal crystals, gels, and glasses under shear

• Applicant: Christoph Eisenmann
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2005 to 2007
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5453641

Colloidal suspensions have become an indispensable model system to study the properties of various phases as crystals, gels, or glasses. Due to the comparably large size and accordingly slow dynamics of the suspended particles they can - in contrast to atomic systems - be monitred on a single particle level. This allows a direct access to microscopic properties as the local structures, appearance of defects, dynamics of single particles (connected to e.g. the cage effect in glasses), etc. Although colloidal crystls as well as gels and glasses have been investigated intensively by light scattering techniques and rheological experiments, important features are still open. Some of these unsettled questions could be illuminated by studies on a micrsocopic level. Besides the widespread and succesful method of confocal microscopy two recently developed techniques (laser diffraction microscopy and coherent anti-Stokes Raman scattering) facilitate a microscopic as well as a mesoscopic approach. For this work, we suggest to study the influence of shear strain and stress onto colloidal crystals, gels, and glasses combining these methods, some of them simultaneously to gain complementary information. In case of the crystals shear strain can be achieved by sedimentation onto an incommensurate substrate, in all cases shear stress can be applied using a shear cell.

• DFG Programme: Research Fellowships
• International Connection: USA
• Hosts: Professor Dr. Georg Maret; Professor Dr. David A. Weitz