Dresden 2009 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 39: POSTERS Colloids and Liquids

CPP 39.16: Poster

Thursday, March 26, 2009, 17:00–19:30, P3

Modifications in torsional resonance spectroscopy of charged sphere colloids — •Alexander Reinmüller, Nina Lorenz, Lucas Chanchetti, Thomas Todd, Hans-Joachim Schöpe, and Thomas Palberg — Institut für Physik der Universität Mainz, Staudingerweg 7, D-55099 Mainz, Germany

Morphological changes in colloidal crystals may have strong effects on the elastic properties of the corresponding solids. A modified experimental setup for measuring the shear moduli of torsionally oscillating charged sphere colloidal crystals by light scattering [1] [2] is presented: On the detection side a frequency analyzer is used instead of the conventional lock-in-amplifier. On the excitation side a white noise generator can be used instead of a simple sine generator. A comparison with the older method shows the following advantages: The measurement times can be reduced, structural changes can be controlled more precisely and coupling of resonance modes can be observed. Particular attention is paid to keeping the excitation amplitude small enough to leave the sample uninfluenced during thermal annealing.

[1] E. Dubois-Violette et al., J. Physique 41 (1980) 369-376

[2] H. J. Schöpe, T. Palberg, J. of Colloid and Interface Science 234, 149-161 (2001)