Abstract

The linearized Poisson-Boltzmann equation is considered for boundary conditions corresponding to a fixed point-charge ion near the planar boundary between an electrolytic solution and a dielectric substrate. Use of the Fourier expansion for this fixed charge density allows the mean potential to be synthesized in the form of a simple quadrature. Subsequently, it is possible to compute the reversible work necessary to displace the ion atmosphere surrounding this charge into one hemisphere as the charge is brought up to the interface from the interior of the electrolyte phase. Implications for ionic adsorption processes are discussed. The result of a similar analysis for the mean potential surrounding a point dipole oriented normally to the boundary is also presented.