Nonpolarized ITIES, potential drop

The tip current depends on the rate of the interfacial IT reaction, which can be extracted from the tip current vs. distance curves. One should notice that the interface between the top and the bottom layers is nonpolarizable, and the potential drop is determined by the ratio of concentrations of the common ion (i.e., M ) in two phases. Probing kinetics of IT at a nonpolarized ITIES under steady-state conditions should minimize resistive potential drop and double-layer charging effects, which greatly complicate vol-tammetric studies of IT kinetics. 

A reference electrode which can directly be dipped in the organic phase is not available, except the AgPh4B/Ag electrode [44]. It is customary to use a nonpolarized liquid-liquid interface, i.e., a reference ITIES. The potential drop across this interface is primarily determined by an ionic species distributed commonly in both aqueous and organic phases. There are two points to be taken into account in using this reference ITIES the deviation from nernstian behavior and limited reversibility. 

Elegant studies of electrocapillarity of a nonpolarized ITIES by Gavach et al. [48] showed that the tetraethyl-, tetrapropyl- and tetrabutylammonium ions are not adsorbed within the compact layer and suggested that the interface is made of two space charge layers, described by the Gouy-Chapman theory, on either side of a central compact layer [49-51]. In a nonpolarized ITIES, the potential drop across the interface cannot be altered independently of the chemical potential of a salt of ionic constituents in either of the phases. The degree of specific adsorption cannot therefore be quantitatively estimated at a nonpolarized interface [28]. 

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