Stationary potentials

Insertion of Eqs. (18) in (15) results in an Equation for a dissolving solid state membrane electrode in the absence of complexing agents. In case aA = aB = 0 (e.g., pure H20) the stationary potential can be expressed as ... 

Stationary potential-dependent measurements are not the only measurements that can be performed with microwaves. Figure 6 shows a scheme indicating the different techniques that can be used for microwave characterization of semiconductor electrodes. 

In the following section the mathematical derivation of the stationary, potential-dependent, photoinduced microwave conductivity signal, which integrates over all photogenerated charge carriers in the semiconductor interface, is explained. This is a necessary requirement for the interpretation of the PMC-potential curves. 

We ll search for a solution of equation of motion in a stationary potential thermoelectric field with distributed potential. Such a field is generated in a plane-parallel structure (Fedulov, 2003) with distributed potential (fig. 1). The potential thermoelectric field in this structure can be described by the following independent expressions ... 

In the standard (Dirac-Pauli) representation, the Dirac equation for an electron in the field of a stationary potential V reads... 

Protection of quantum states from the influence of noise is important. It has been shown that the alternating transport of a EEC generated by the fast-forward driving field suppresses the influence of a fluctuating random potential on the EEC [47], The EEC is kept undisturbed for a longer time than is characteristic of the simple trapping with a stationary potential because the effective potential, which the quanmm state feels, becomes uniform when the transport velocity is sufficiently large. 

Schell et al. present evidence that the role of anions in the electrocatalyzed oxidations of formic acid in current-control experiments can be even more than simply blocking reactive surface sites [132-135]. They conjecture that the adsorbed anions affect the nature and reactivity of surface water and OH, and thus their reaction with surface CO. Most remarkable results were obtained when perturbing an aqueous solution containing 0.1 M HCOOH and 0.5M HCIO4 by a small amount of HBF4 [133]. The addition of BF4 anions caused more than a 60% increase in the value of the applied current for which low-valued stationary potentials remain stable. The current increases by more than 50% at relevant potential values in potential-control experiments. Together with the overall reaction rates the nonlinear behavior exhibited by formic acid oxidation changed drastically in the presence of a small amount of BF4. ... 

Fig. 45. (a) Cyclic voltammogram and (b) stationary potential domains during the reduction of S20g2 on a Ag ring electrode at fixed outer potential (t/ = —1.13V) [42], The end of a Haber-Luggin capillary was positioned on the axis of the ring and close to the WE. 

Fig. 50. Calculated stationary potential pattern that forms...

Fig. 69. Stationary solutions of Eqs. (61a,b) for different values of the external voltage U [33], From top to bottom, U is increased. For the highest and lowest value of U, the homogeneous state is stable, whereas for intermediate values the only stable solutions are stationary potential patterns with a defined wavelength.

If the whole semiconductor/electrolyte interface is illuminated uniformly, both conjugate reactions proceed at the same rate over the same areas on the interface. The stationary potential of an illuminated semiconductor is thus a mixed potential. If the surface of a semiconductor, homogeneous in its composition and properties, is illuminated nonuniformly, in the illuminated and nonillumi-nated areas conditions will not be identical for electrochemical reactions. Here the conjugate reactions appear to be spatially separated, so that we can speak about local anodes and cathodes. This situation is deliberately created, for example, for selective light-sensitive etching of semiconductors (see Section V.2). 

Figure 50. Experimental setup for measuring spatiotemporal pattern formation on a rotating ring electrode with a stationary potential probe. (After Flatgen and Krischer. )...

The corroding metal potential is inconstant since it is affected by corrosion factors var3ung in time. As soon as the electrochemical corrosion becomes stationary, the electrode potential acquires a constant value Ecorr- Once the stationary potential or the corrosion potential has stabilized, velocities of the anodic (1.2) and cathodic (1.3) reactions on the electrode equalize. Ecorr measured in standard conditions relative to some standard reference electrode... 

With this aim, the kinetics of the variation of the polarizing resistance (Rp) of a steel electrode has been studied [118] in the vicinity of its stationary potential when the electrode is in contact with an inhibited polymer film in aqua solutions of electrolytes (HCl and Na2S04). The films were produced by hose extrusion of PE-based compositions with PI (mineral oil) and oil-soluble Cl. 

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