Forward peak current

Its main characteristics are as follows. The height of the wave is 2a/2 the height of a one-electron Nernstian wave rather than twice this height. Thus, the forward peak current is... 

The forward peak current measured under the effect of the kinetic reaction, ik (kinetic current), is a fraction of the peak current id (diffusive current) that one would record at the same scan rate in the absence of the preceding chemical reaction, according to the relationship ... 

This mechanism has some analogy with the dimerization complication. The parameter which distinguishes them is the variation of the peak current with the scan rate. In fact, decreasing the scan rate will allow the chemical reaction to regenerate the initial species Ox, thus causing a significant increase in the forward peak current. 

Finally, if Red) is more easily reduced than Ox (i.e. Ef > Ef), once again one has a single catho-anodic peak-system, Figure 3Id. However, in this case the peaks are sharper. In fact, A.Ep is equal to 28.5 mV and the forward peak current is 2.83-fold larger than that of a one-electron process (i.e. 23/2, according to the Randles-Sevcik equation, Section 1.1). The average potential measured between Ep( and. Epr is, in this case, intermediate between E and Ef. 

Cyclic voltammetry provides a convenient method of recognizing such processes provided the lifetime of the intermediate is less than a minute or so. Consider an idealized reaction pathway (14) which involves the reversible one-electron reduction of a compound M. Of primary interest in the cyclic voltammetric experiment is the ratio of the back- and forward-peak currents, ipb/ip, and the dependence of this ratio upon the scan rate, v. 

Where Ep is the peak potential and 1/2 is the half wave potential. The forward peak current, ip, for a reversible process can be related to the analyte concentration, Co, by the Cottrell equation (7). ... 

Fig. 19. Working curves for the ratio of backward and forward peak currents, Ipij/Ipf, on the dimensionless parameters (A) = (l/K)((r/ks) -, curve 1 for the QevE mechanism,...

As it has been stressed at the beginning of this survey, it is important for an experimenter to be able to calculate theoretical responses. Once the experimental response has been properly manipulated > e,g. the noise has been filtered off, the background has been subtracted, convolution or deconvolution operations have been possibly performed the problem is how to perform the comparison with theoretical responses in order to 0 establish the nature of the mechanism ii) determine the relevant thermodynamic and Idnetic parameters. The first step, i.e. the identification of the type of the operative mechanism, can be simply based on the comparison of the trends of some significant quantities of experimental and computed responses. As an example, in the case of cyclic voltammetric experiments, the forward peak potential, the ratio between backward and forward peak currents, the difference... 

Methyl viologen dication (MV ) and ferrocene (Fc) in 0.1 M SDS/0.1 M NaCl, and ferrocene in 0.1 M CTAB containing either 0.1 M NaCl or KBr were used to obtain D at a series of concentrations of the electroactive probe. Standard CV criteria confirmed reversible electrochemistry for MV2+ and Fc in the ionic micellar systems chosen 2,3i Plots of forward peak current (ip) vs V /2 showed excellent linearity for each electroactive compound. The Randles-Sevcik equation " was used to compute the apparent diffusion coefficient D from the slopes of ip vs plots at each con-... 

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