Redox frequency domain

Topics discussed above are some basic principles and techniques in voltammetry. Voltammetry in the frequency domain where i-E response is obtained at different frequencies from a single experiment known as AC voltammetry or impedance spectroscopy is well established. The use of ultramicroelectrodes in scanning electrochemical microscopy to scan surface redox sites is becoming useful in nanoresearch. There have been extensive efforts made to modify electrodes with enzymes for biosensor development. Wherever an analyte undergoes a redox reaction, voltammetry can be used as the primary sensing technique. Microsensor design and development has recently received... 

It must be expected that a polymer material having a much lower conductivity than polyaniline will give impedance responses revealing the effect of the three time constants obtained in the model. The system investigated was chosen for this reason since pECBZ conductivity and redox capacity [94] correspond to DE = 10 7cm2,s 1 and therefore, for the same layer thickness (500nm), the diffusion time constant would be 0.025 s. Electron diffusion should therefore be detectable in the a.c. and even in the EHD frequency domain. 

The solution of nonlinear evolution equations in the time domain is known analytically only in very simple cases such as reversible redox processes limited by diffusion. For electrochemical nonlinear systems, the treatment of nonsteady-state techniques generally requires calculations that are at least partially numerical. In addition, the solutions found to express the response to a perturbing signal depend specifically on the form of the perturbation. These drawbacks are largely eliminated if the amplitude perturbation is limited to a sufficiently low value to allow the equations to be linearized. In this case, analyses in the frequency domain are very powerful. 

In the previous subsection, the analysis of an ER signal in a frequency domain is restricted to the use of the experimental signal at the formal potential of the redox reaction of interest If we can take a similar approach using the potential... 

Distinction by the spectral characteristics, i.e. wavelength dependence, is well known. When two processes are occurring simultaneously and if the spectrum of one of them is known, deconvolution of the experimental spectral curve enables us to distinguish them. The details of this general method are not given here, but the latter method is described using a practical example of the discrimination of two simultaneously occurring redox processes in the frequency domain. 

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