Attractions between charged colloidal spheres mediated by correlated absorbed ions

Abstract

We describe arrangements of ions capable of producing short-range attractive interactions between pairs of charged colloidal spheres in the low temperature strongly correlated limit. For particles of radius $R$ with bare charge $Z$ and comparable absorbed charge $-N$ ($N \sim Z$), the correlations contribution to the spheres self-energy scales as $N^{3/2}/R$, and as $N/R$ for the interaction energy between two touching spheres. We show that the re-arrangement of charges due to polarization plays an insignificant role in the nature and magnitude of the interaction.