The Van Der Waals Interaction Across Non‐Uniform Electrolyte

The interaction of like colloidal particles separated by electrolyte is the resultant of the attractive Vander Waals force and the repulsive electrostatic forces, screened by the non‐uniform electrolyte. Hitherto, these contributions have been estimated separately. In this paper, the coupling of the low frequency electromagnetic fluctuations to the static charge distribution between two planes is examined. This coupling is expressed by a pair of second order coupled differential equations, which are solved exactly. The resulting eigenvalue equation is derived and the zero frequency contribution to the Vander Waals free energy calculated.