Pair interaction of charged colloidal spheres near a charged wall - art. no. 050401

Although equally charged colloidal particles dispersed in clean water are e xpected to repel each other, an unexplained long-range attraction has consi stently been reported for charged colloidal spheres confined by charged mac roscopic surfaces. We present an alternative equilibrium measurement of the pair interaction energy for charged spheres near a single charged wall. An alyzing their radial distribution functions for different concentrations re veals a purely repulsive sphere-sphere interaction that is well described b y a screened Coulomb potential.