The demodulation method

In order to avoid a lengthy discussion, we focus attention on the essential second-order parameter [SF] specified in Sect. 2.4.4. It is convenient to define a related quantity SF = [SF] (RT/nF) (2o H Cd/./a )2 so that, from Table 5 and eqn. (84), it follows 

As this method is pre-eminently suitable to fast reactions, only the case of a d.c. reversible system will be considered. Then immediately, the thermodynamic relationships between the partial derivatives as derived by Reinmuth [24] can be introduced. These are [7, 24] 

After substitution of these relationships into X, Xj and X(, as defined in Table 4, a final expression for S  

If the rate equation is first order in cG and cR, RR and OO are equal to zero and FF is the only second-order parameter that remains. It is easily verified that in this case 

The conclusion is that Sp contains explicit information on both ks (via Ph = Ph h2) and a (via FF/F). The plots of Sp vs. potential in Figs. 31 and 32 indicate its diagnostic power as compared with the first-order parameter p.  

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Also in the demodulation method, controlled-current perturbation is applied, which means that here, too, eqn. (84) is to be used to substitute El by a term containing the squared amplitude of the current density,. ... 

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