Nernst's diffusion layer

Also contains definition of: effective thickness of diffusion layer
https://doi.org/10.1351/goldbook.N04108
A fictitious layer corresponding to the dotted straight lines of the diagram which shows the concentration profile along the direction perpendicular to an electrode surface. The thickness \(\delta \) of this layer is called the effective (or equivalent) thickness of the @[email protected] Its definition is apparent from the figure. It is the thickness which the @[email protected] layer would have if the concentration profile were a straight line coinciding with the tangent to the true concentration profile at the @[email protected], and that straight line were extended up to the point where the bulk concentration is reached. \(\delta \) has a formal significance only. It is simply another way of writing the @[email protected] \(k_{\text{d}}\) defined in terms of a @[email protected] instead of a conductivity.
N04108.png
Source:
PAC, 1981, 53, 1827. (Nomenclature for transport phenomena in electrolytic systems) on page 1837 [Terms] [Paper]