Dynamics in dense suspensions of charge-stabilized colloidal particles
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
* e-mail: email@example.com.
Accepted: 7 January 2008
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 φ ⩽ 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 –
© EDP Sciences, Società Italiana di Fisica and Springer-Verlag, 2008