Dynamics in dense suspensions of charge-stabilized colloidal particlesA. Robert1, J. Wagner2, W. Härtl3, T. Autenrieth4 and G. Grübel4
1 European Synchrotron Radiation Facility, B.P. 220, F-38043, Grenoble, France
2 Saarland University, Physical Chemistry, 66123, Saarbrücken, Germany
3 Wallburg-Realschule, 97483, Eltmann, Germany
4 Hasylab/DESY, 22607, Hamburg, Germany
(Received 18 September 2007 / Published online 12 February 2008)
The dynamic behavior of charge-stabilized colloidal particles in suspension was studied by photon correlation spectroscopy with coherent X-rays (XPCS). The short-time diffusion coefficient, D(Q) , was measured for volume concentrations ≤ 0.18 and compared to the free particle diffusion constant D0 and the static structure factor S(Q) . The data show that indirect, hydrodynamic interactions are relevant for the system and hydrodynamic functions were derived. The results are in striking contrast to the predictions of the PA (pairwise-additive approximation) model, but show features typical for a hard-sphere system. The observed mobility is however considerably smaller than the one of a respective hard-sphere system. The hydrodynamic functions can be modelled quantitatively if one allows for an increased effective viscosity relative to the hard-sphere case.PACS
82.70.Dd - Colloids.
05.40.Jc - Brownian motion.
61.05.C- - X-ray diffraction and scattering. Correspondence: firstname.lastname@example.org.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2008