INTERACTION FORCES IN QUASI-2-DIMENSIONAL CHARGED DISPERSIONS

A ''predictor-corrector'' inversion of the Ornstein-Zernike equation h as been presented for extracting the pair potential u(r) between collo idal particles from the radial distribution function g(r) or the stati c structure factor S(q) of dispersions confined to a single layer. The method, an extension of the three-dimensional analog presented earlie r, is used to obtain u(r)'s for recently published experimental data o n confined dispersions. The results confirm unambiguously the existenc e of an attractive force in u(r), even for a set of data that has been described using a purely repulsive u(r) previously. We also illustrat e the potential effect of experimental artifacts in imaging experiment s that can lead to an apparent attraction in u(r) and offer an explana tion for the persistence of attraction or its disappearance as a funct ion of the distance between the plates used to confine the dispersions in the experiments.