Image potential near a dielectric–plasma‐like medium interface

The effect of penetration of an electric field into the metal, electrolyte, solution, or other plasmalike medium (PLM) on the image‐potential energy in a dielectric adjacent to such a PLM is studied. The asymptotics of classical attraction of a test charge to an “impenetrable metal surface” at large distances and of effective interaction with “dielectric‐dielectric interface” at small distances are found. The latter results in a repulsion of a charge from the boundary, when the dielectric constant of the background medium, in which plasma particles are dissolved, is smaller than the permittivity of the dielectric. A minimum of the image‐potential curve is situated between the “repulsive” and “attractive” limiting branches. Thus an adsorption minimum is predicted within the scope of purely electrostatic considerations, the value of the “desorption energy” being estimated.