Alternating voltage perturbation

Let us suppose that a small alternating voltage perturbation is applied to the working electrode around a constant dc potential,... 

Frequency Response Analysis the response of an electrode to an imposed alternating voltage or current sign of small amplitude, measured as a function of the frequency of the perturbation. Also called Electrochemical Impedance Spectroscopy. 

To carry out this type of study, a small AC amplitude voltage perturbation, AV ico,/), is applied, superimposed onto a DC bias voltage component, and the resulting alternating current response and its phase, A/(co,t), is measured [123,132], Then, the electrochemical impedance of the system is thus defined as... 

For reversible systems there is no special reason to use these techniques, unless the concentration of the electrochemical active species is too low to allow application of DCP or cyclic voltammetry. For a reversible electrochemical system, the peak potentials in alternating current voltammetry (superimposed sinusoidal voltage perturbation) and in square-wave voltammetry (superimposed square-wave voltage... 

The capacitive nature of the adsorption pseudocapacitance can be further illustrated by considering its response to an alternating voltage (AC) perturbation. Let us assume that a low-amplitude sinusoidal voltage signal is applied to a system at equilibrium. The sinusoidal waveform can be expressed by the equation... 

Methods for measuring the impedance can be divided into controlled current and controlled potential [2, 4, 81]. Under controlled potential conditions, the potential of the electrode is sinusoidal at a given frequency with the amplitude being chosen to be sufficiently small to assure that the response of the system can be considered linear. The ratio of the response to the perturbation is the transfer function, or impedance, Z, when considering the response of an AC current to an AC voltage imposition and is defined asE = IZ, where E and I are the waveform amplitudes for the potential and the current respectively. Impedance may also be envisaged as the resistance to the flow of an alternating current. 

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