Current-potential curves INDEX

Although the usual way of analyzing the influence of the kinetics of the electron transfer on the SWV response is based on the variation of the frequency at fixed values of the staircase and square wave amplitude, a new approach for carrying out this analysis has been proposed based on the study of the influence of the square wave amplitude sw on the current potential curves at a fixed value of the frequency (or the time pulse) [19, 33, 34], The square wave amplitude has been used rarely as a tool in mechanistic and kinetic studies. One of the main reason is that, as stated in Sect. 7.1, in SWV the current is plotted versus an index potential which is an average potential between the forward and reverse potentials (see Eq. (7.7)) and leads to a discrepancy between the plotted and actual potentials at which the current is sampled. Therefore, the role played by Esw in the process is complex. 

Theory of the Conversion of Resistance to an Overpotential. The correlation between impedance measurements and current/potential curve was first described by Wagner [2002] and is given schematically in Figure 4.5.40 and Figure 4.5.41. The polarization resistance of the cell Rceii) measured at [/ (index n = counter) corresponds to the tangent to the current/potential curve at that potential ([/ ). The polarization resistance of the cell is the impedance at frequencies near 0 Hz where only ohmic parts attract attention. To obtain the polarization resistance of the cell, one has to extrapolate the simulated impedance (model) at very low fre-... 

In the case of DMPV (see Scheme 7.2), the treatment followed in Sect. 4.2.4.1 for Differential Double Pulse Voltammetry (DDPV) for one and two polarizable interfaces can be used because the equilibrium is quickly reestablished during the longer period Therefore, the peak potential of the DMPV curves when the current is plotted versus the index potential is... 

The barrier index can be defined operationally. For any given emitter temperature and output current, it is possible to adjust cesium pressure, spacing, and collector temperature to maximize the power output. The spacing envelope of the optimized performance curves is shown in Fig. 6 for a converter with an emitter temperature of 1800 K. This envelope is shifted by a constant poterrtial difference from the Boltzmann line, which represents the ideal cmrent-voltage characteristic. This potential difference is defined as the barrier index. In Fig. 6, the barrier irrdex of 2.1 eV represents good performance for a thermiorric converter with bare metal electrodes, corresponding to Fd 0.5 eV and c — 1-6 eV. The equation for the Boltzmarm line is... 

In this work polarization curves will be modeled. The current response (= output y) to a linearly changing potential (= input Mq) is measured in different pxjints (with index /) and... 

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