Small-amplitude sinusoidal alternating

The most common applications of ACP/ACV involve the application of a small-amplitude sinusoidal alternating potential superimposed onto a ramp voltage. The resulting current is an alternating current, the d.c. component being filtered out by use of a phase-sensitive current detector. This is possible... 

The traditional way is to measure the impedance curve, Z(co), point-after-point, i.e., by measuring the response to each individual sinusoidal perturbation with a frequency, to. Recently, nonconventional approaches to measure the impedance function, Z(a>), have been developed based on the simultaneous imposition of a set of various sinusoidal harmonics, or noise, or a small-amplitude potential step etc, with subsequent Fourier- and Laplace transform data analysis. The self-consistency of the measured spectra is tested with the use of the Kramers-Kronig transformations [iii, iv] whose violation testifies in favor of a non-steady state character of the studied system (e.g., in corrosion). An alternative development is in the area of impedance spectroscopy for nonstationary systems in which the properties of the system change with time. 

This term is used to cover a range of techniques in which the mean potential is controlled potentiostatically and swept over a range while a small amplitude, relatively high frequency alternating potential superimposed on the slowly-varying sweep is used to excite a sinusoidal response in the current, which is... 

In this technique, a linear voltage ramp is modulated with a sinusoidal alternating voltage of small amplitude (A . = 10-100 mV) and low frequency (/=5-100Hz). The superimposed alternating voltage causes an alternating current, whose size depends on the instantaneous value of... 

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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