Regensburg 2002 – wissenschaftliches Programm

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DY: Dynamik und Statistische Physik

DY 46: Poster

DY 46.20: Poster

Donnerstag, 14. März 2002, 15:30–18:00, D

Determine the interaction potential in charged colloidal model systems — •Hans Joachim Schöpe — Institut für Physik, Universität Mainz, Staudinger Weg 7, D-55099 Mainz

We systematically determine the phase boundaries in different charged colloidal model systems under full deionised conditions using a combination of static light scattering, torsional resonance spectroscopy and bragg microscopy. The shear modulus G of colloidal solids is measured as a function of particle number density np using torsional resonance spectroscopy to determine the interaction potential at the nearest neighbour distance.

We present the first experimental access of the pair energy of interaction in charged colloidal suspensions which describes both the elastic properties and the fluid crystalline phase behaviour. The excellent agreement of the theoretical and the experimental phase boundaries as well as the outstanding conformity of the elastic data measured with theoretical description demonstrate an experimental verification of a Debye-Hückel potential proposed in the Poisson Boltzmann Cell model and the performance of our experimental techniques. Surprisingly the observed bcc fcc phase boundary does not fit to theoretical predictions.