โ Scribed by K. Robinson; S. Levine
No coin nor oath required. For personal study only.
The inner or compact region at the charged mercury/aqueous electrolyte interface is usually regarded as havinga dielectric constant which is considerably smaller than the value for bulk water and which increases with distance from the mercury boundary. In the previous papers of this series 1"2, henceforth referred to as I and II, this dielectric constant was assumed to change abruptly at the two planes which characterize the inner region. These are the inner Helmholtz plane (i.h.p.) on which the centres of specifically adsorbed counter-ions are situated and the outer Helmholtz plane (o.h.p.) which defines the position of nearest approach to the mercury surface of non-adsorbed diffuse layer ions and also constitutes one boundary of the inner region. Wroblowa and Mfiller 3 have questioned the validity of such a dielectric model of the inner region on the grounds that no sharp discontinuity in dielectric constant can exist at the o.h.p. In a series of important papers Buff et al. 4-7 have examined the effect of a smoothly varying dielectric constant (where both the dielectric constant and its rate of change with distance are continuous functions) on the image potential of a point charge placed near the interface. In particular, Clay et al. 7 calculated image effects at a metal/water interface where the dielectric constant is increasing continuously and smoothly across the inner region to reach the aqueous bulk value at its boundary. These authors developed a method of treating an anisotropic inner region with different dielectric constants parallel and normal to the interface, although their calculations with specific dielectric constant functions were interpreted on the simpler isotropic system. Since virtually nothing is known about the degree of possible anisotropy and in addition any dielectric constant profiles are somewhat conjectural, for the present it should be sufficient to examine the isotropic case only. This permits a considerable simplification in the theory developed by In the present paper we shall use one of their models for the dielectric constant variation to determine the discreteness-of-charge potential of an adsorbed ion in the inner (egion. A discontinuity in the dielectric constant or even in the first derivative of the * To whom correspondence should be addressed.
๐ SIMILAR VOLUMES
The rate constant k should not be confused with the variable of integration k in this paper, as in (2.3) or (5.4). Similarly the transfer coefficient c~ differs from the a in (2.4).