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On the theory of ion transfer rates across the interface of two immiscible liquids

Marcus, R. A. (2000) On the theory of ion transfer rates across the interface of two immiscible liquids. Journal of Chemical Physics, 113 (4). pp. 1618-1629. ISSN 0021-9606. http://resolver.caltech.edu/CaltechAUTHORS:MARjcp00

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Abstract

Ion transfer across the interface of two immiscible liquids involves a mechanism for initiating desolvation from the first liquid, A, and concerted solvation by the second, B. In the present article a mechanism is considered in which this initiation is facilitated by the ion attaching itself to the tip of a solvent protrusion of B into A. (Protrusions have been observed in computer simulations and termed "fingers" or "cones.") It is presumed that the most effective protrusion represents a balance between two opposing effects: the more convex the protrusion the less probable the ion/protrusion formation but also the less the resistance to extrusion of the intervening liquid between the ion and the surface. An analogy of the latter to hydrodynamics is noted, namely, the more convex the surface the less the frictional force it exerts on the approaching ion. After diffusion in coordinate and solvation space across the interfacial region, the final detachment of the ion from solvent A is assumed to occur from a protrusion of A into B. Existing data on ion transfer rates are discussed, including the question of diffusion vs kinetic control. Computer simulations that correspond to the experimental conditions in realistic liquids for measurement of the electrochemical exchange current rate constant k0 are suggested. They can be used to test specific theoretical features. With a suitable choice of systems the need (and a major barrier to the simulations) for having a base electrolyte in such simulations can be bypassed. An experiment for the real-time observation of an ion leaving the interface is also suggested.


Item Type:Article
Additional Information:©2000 American Institute of Physics. (Received 3 March 2000; accepted 27 April 2000) It is a pleasure to acknowledge the support of this research by the Office of Naval Research and the National Science Foundation. It is a pleasure, too, to acknowledge the very helpful correspondence with F. Anson, I. Benjamin, H. H. Girault, T. Kakiuchi, V. Marecek, and Z. Samec, and to dedicate this paper to Roger Parsons on the occasion of his retirement from the editorship of the Journal of Electroanalytical Chemistry.
Subject Keywords:solubility; hydrodynamics; solvation
Issue or Number:4
Record Number:CaltechAUTHORS:MARjcp00
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:MARjcp00
Alternative URL:http://dx.doi.org/10.1063/1.481950
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:2121
Collection:CaltechAUTHORS
Deposited By: Archive Administrator
Deposited On:09 Mar 2006
Last Modified:26 Dec 2012 08:47

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