Redox ER Signal in Frequency Domain

For kinetic measurements using the ER signal, Eq. (14) is important, although its validity should always be confirmed by experiments. This equation ensures a quantitative relationship between ac faradaic current and the ac reflectance signal, insofar as we can assume that RTjn F (linear response approxima- 

When a redox reaction is only the origin of the ER signal and the change of reflectance is directly proportional to the amount of the redox couple intercon-verted between oxidized and reduced state, Rac can be written [9, 56, 69] as 

2 UV-visib e Reflectance Spectroscopy of Thin Organic Films at Electrode Suifaces 

We now use an equivalent circuit representing an electrode/solution interface where the electrode surface is covered by an electroactive monolayer. The simplest circuit is shown in Fig. 2.18. We assume that the molecules in a Langmuir monolayer undergo an n-electron transfer reaction in response to ac and that the ER signal is exclusively due to this faradaic process [69]. The faradaic process of the surface-confined species at the formal potential is represented by a series connection of a constant capacitance associated with the redox reaction of the adsorbed species Q and a charge transfer resistance Ret. where Q is written for a Nernstian process as 

7 7 Measurement of Electron Tranfer Rate using ER Measurement 75 When using a Buter-Volmer type rate equation, R t at is written as 

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