Double layer structure at the mercury/N-methylformamide interface

Abstract

Interfacial capacity data for the Hg/ N -methylformamide interface are presented for the polarization range of the electrode in the temperature interval 3 to 86°C. Ionic specific adsorption is shown to be negligible on the basis of the usual criteria for charge densities between 0.06 C m −2 and −0.16 C m −2 . Inner layer capacity data have been calculated on the basis of the Gouy-Chapman theory as functions of electrode charge density and temperature. The maximum variation in this quantity occurs at charge densities just negative of the maximum on the inner layer capacity curve. The dielectric properties of the inner layer are examined on the basis of a four-state model which assumes both monomers and clusters to be present in the surface monolayer of solvent molecules. A very good fit between theory and experiment is obtained when it is assumed that the clusters are dimers with no net permanent dipole moment. The consequences of the model regarding the temperature dependence of the interfacial properties, and the relation of the present results to those for other similar solvents are also discussed.