Electrode edge effect

In an endeavor to reduce the residence time below the level dictated by the capacity of the vacuum system the electrode area was steadily reduced (Reactors A1 to A4). The results obtained are detailed in Figure 3 and show that the yield fell and the discharge itself altered radically because of the increased influence of electrode edge effects. 

Relative permittivity Dissipation factor lEC 60250 >60 X >60 X 2 At 100-Hz and 1-MHz frequency compensate for electrode edge effects. 

Null methods are used at frequencies up to 50 MHz and results are compensated for electrode edge effects. Null method with resistive or induciive ratio arm capacitance bridge suggested for frecjuencies of < 1 Hz to a few MHz. 

Miller, L. S. and Kershaw, R., Calculated electrode-edge effects in flash-excited charge-transits and comparison with measurements on sulfur, /. Phys. Chem. Solids, 40, 839, 1979. 

The conditions for planar diffusion are theoretically fulfilled only if the electrode surface is very large. In case of finite disk electrodes, edge effects arise and linear diffusion is no longer linear overall the electrode surface (Fig. 15.3). Diffusion also develops parallel to the electrode surface in the radial direction. However, if the radius of the disk electrode is large enough with respect to the diffusion layer thickness (as is the case of common employed disk electrode of millimeter size), edge effects can be neglected and Cottrell equation accurately accounts for the current profile at the electrode surface. These electrodes are nowadays called either conventional or macroelectrodes. ... 

EC mechanism, 34, 42, 113 E. Coli, 186 Edge effect, 129 Edge orientation, 114 Electrical communication, 178 Electrical double layer, 18, 19 Electrical wiring, 178 Electrocapillary, 22 Electrocatalysis, 121 Electrochemical quartz crystal, microbalance, 52 Electrochemihuiiinescence, 44 Electrodes, 1, 107... 

The UMEs used in bioarrays can be divided into three types disk, ring, and strip electrodes. The theory of the disk, ring, and strip UMEs has been extensively studied [97-100], Due to the edge effect, the profile of the mass diffusion to the ultramicroelectrode surface is three dimensional, and can significantly enhance the mass transportation in comparison to the conventional large electrode with one-dimensional mass transportation. The steady-state measurement at a planar UME can be expressed as... 

Diffusion of electroactive species to the surface of conventional disk (macro-) electrodes is mainly planar. When the electrode diameter is decreased the edge effects of hemi-spherical diffusion become significant. In 1964 Lingane derived the corrective term bearing in mind the edge effects for the Cotrell equation [129, 130], confirmed later on analytically and by numerical calculation [131,132], In the case of ultramicroelectrodes this term becomes dominant, which makes steady-state current proportional to the electrode radius [133-135], Since capacitive and other diffusion-unrelated currents are proportional to the square of electrode radius, the signal-to-noise ratio is increased as the electrode radius is decreased. 

For Eredox more negative than the flat band potential (b) there is little band bending (no barrier) and the electrode is reversible with respect to the redox couple and is in ohmic contact (a). For Ere between the flat band potential and some positive potential represented in (c) the drop in potential occurs across the semiconductor and the behavior is ideal because the band bending varies following Equation 1. For more positive Ereadditional potential drop across the semiconductor does not occur because the semiconductor is inverted at the surface, and the band edges effectively shift more positive as the potential drop occurs across the Helmholtz... 

Of the many complex transport geometries, some of the most important are those encountered with inlaid electrodes (Fig. 14) [25— 30], in which the electrode is planar and embedded in an insulator whose surface is a continuation of the electrode plane. If such an electrode is large, it may be appropriate to treat it as a case of planar transport, with a correction for the edge effect [31, 32], For a small inlaid electrode, however, or for experiments of long duration, such an approximation is no longer valid. 

Certain criteria have to be met in the construction of hydrodynamic electrodes, such that the laminar flow pattern, which is used in the derivation of the theoretical equations, is conformed to. Thus edge effects, which are due to the fact that electrode and surrounding mantle are not of infinite size and which are also dependent on cell dimensions, must be minimised. The shape of the electrode and mantle is important the surfaces must be smooth and there must be no discontinuities or electrolyte penetration at the electrode/mantle junction. 

Edge effects at rotating disc electrodes caused by using different electrode shapes have been discussed by Blurton and Riddiford [111]. Their conclusion was that a bell-shaped mantle was best, although cylindrical electrodes, which are widely used, are perfectly sufficient in... 

The cell for rotating electrodes, Fig. 7, is usually cylindrical and surrounded by a water jacket for thermostatting purposes, but as long as the cell walls are more than 1 cm or so from the rotating assembly, there are usually no cell edge effects. The auxiliary electrode is very often contained in a separate compartment behind a glass frit in order to avoid contamination problems. A Luggin capillary, where required, can be positioned in various ways unless it is more than 0.5 cm from the electrode, it must be placed under the centre of the disc in order to avoid a non-equipotential surface this can cause some problems with disturbance of the fluid flow. 

It should be taken into account that this is only valid for the textile electrode investigated in this work, because this parameter is also dependent on the roughness of the surface. The roughness is definitely the cause of this edge effect, because it is absent when using smooth palladium electrodes. 

Although neither a wire nor a thin ribbon is a strict example of a WE supporting base geometry, we can expect that for both cases, i.e. essentially one-dimensional electrodes in a three-dimensional electrolyte, edge effects are much less pronounced than in the case of two-dimensional electrodes surrounded by an insulating plane. Hence, we can tentatively interpret the observations by assuming that the accelerated... 

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