THE ROLE OF LATERAL INTERACTIONS IN DETERMINING THE PROPERTIES OF A DIPOLAR MONOLAYER AT A POLARIZABLE INTERFACE

A statistical-mechanical description of a monolayer of solvent dipoles at a polarizable interface is presented in which the dipoles can take up three orientations with respect to the electrical field, namely, in its direction, against it, or perpendicular to it. The approach is based upon the Kikuchi method in which dipole-dipole interactions within an elementary cluster containing, in the present case, three molecules are treated exactly whereas those outside of the cluster are treated in the mean-field approximation. The differential capacity and monolayer entropy are calculated with consideration of lateral interactions between dipoles in the parallel orientation, and without these interactions. It is shown that the lateral interactions play an important role in determining monolayer properties near the zero charge potential. It is concluded that a more realistic description of such a monolayer can be obtained if the number of molecules in a basic cluster is significantly increased. © 1990 American Institute of Physics.