ER Signal Originated from Non-Faradaic Processes - a Quick Overview

Reprinted from Ref [81]. Copyright 1996 with permission from Elsevier. 

ER Signal Originated from Non-Faradaic Processes - a Quick Overview 

Many of the dynamic processes occurring on the electrode surface take place without the accompanying electron transfer process. Such processes can be represented by adsorption-desorption or change of electric dipole orientation. We need to gain sensitive access to the non-faradaic processes to track the non-fara-daic dynamics of molecular assembhes on electrode surfaces. The following non-faradaic processes can be the targets of the ER measurements. 

Adsorption-desorption processes This process is the interconversion of molecular species between the soluble and the surface-confined state. This may be detectable when the two states exhibit a difference in light absorption. The soluble state gives rise to an absorption spectral feature, while the adsorbed 

State exhibits a reflection spectral feature. These two features are distinguishable in many cases. Otherwise, the adsorption-desorption process can stiU be detectable when an ER signal from the underlying electrode surface varies with this process or when this process also interconverts the orientation of the molecules between ordered and random. We have actually succeeded in detecting adsorption-desorption on an HOPG electrode for MB [25] and rho-damine dyes [82]. 

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