Eur. Phys. J. E (2008) 25: 77-81
https://doi.org/10.1140/epje/i2007-10265-5

Regular Article

Dynamics in dense suspensions of charge-stabilized colloidal particles

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

^* e-mail: aymeric@slac.stanford.edu.

Received: 18 September 2007
Accepted: 7 January 2008
Published online: 12 February 2008

Abstract

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.