Scanning constant current method

The electrolysis of the studied systems was carried out in the same cell as voltammetry measurements under the mode of either constant current or voltage. In the constant current mode, the applied current density was in the range of 0.01 0.2 A/ sm2 with reference to the surface area of the cathode before starting the electrolysis. Semi-immersed glassy carbon plate electrodes (cathode area - 5 sm2, anode area - 10 sm2) were used while electrolysis experiments. A powder product was either settled down onto the crucible bottom or assembled on the cathode in the view of electrolytic pear . The deposit was separated from salts by successive leaching with hot water. Thereafter, the precipitate was washed with distilled water by decantation method several times and dried to a constant mass at 100 - 150 °C. The electrolysis products were analyzed by chemical and X-ray phase analyses, methods of electron diffraction and electronic microscopy (transmission and scanning). 

STM imaging modes are either constant current imaging (CCI) or else constant height imaging (CHI). The CCI mode is the most commonly used method of imaging. The STM tip is scanned laterally (x, y) across a sample surface by variations in the respective and Uy... 

Fast scan measurements, i.e. for investigations of the dynamics of surface diffusion or reconstruction are done preferably in constant height instead of constant current mode because no electronic feedback circuit, limiting response time and scan speed, is involved in this mode. Obviously this works only with very smooth electrode surfaces. An electronic setup (bipotentiostat) that allows fast transient methods combined with scanning probe microscopies has been reported [21]. 

Scanning Probe Methods, Scheme 1 Scheme of scanning tunneling microscopy in the constant height mode left) and the constant current mode right) X, Y, and Z designate the respective piezodrive... 

The cyclic voltammograms of ferrlcyanlde (1.0 mM In 1.0 M KCl) In Fig. 2 are Illustrative of the results obtained for scan rates below 100 mV/s. The peak separation is 60 mV and the peak potentials are Independent of scan rate. A plot of peak current versus the square-root of the scan rate yields a straight line with a slope consistent with a seml-lnflnlte linear diffusion controlled electrode reaction. The heterogeneous rate constant for the reduction of ferrlcyanlde was calculated from CV data (scan rate of 20 Vs using the method described by Nicholson (19) with the following parameter values D 7.63 X 10 cm s , D, = 6.32 X 10 cm s, a 0.5, and n =1. The rate constants were found to be... 

Method involves placing a specimen between parallel plate capacitors and applying a sinusoidal voltage (frequencies ranging from 1 mHz to 1 MHz) to one of the plates to establish an electric field in the specimen. In response to this field, a specimen becomes electrically polarized and can conduct a small charge from one plate to the other. Through measurement of the resultant current, the dielectric constant and dielectric loss constant for a specimen can be measured. The sharp increases in both the dielectric constant and the dielectric loss constant during a temperature scan are correlated with the occurrence of Tg... 

This method is sometimes abbreviated to LSV. In this method, a static indicator electrode (A cm2 in area) is used and its potential is scanned at constant rate v (V s-1) from an initial value ( ) in the positive or negative direction (Fig. 5.18). A typical linear sweep voltammogram is shown in Fig. 5.19. In contrast to DC polar-ography, there is no limiting current region. After reaching a peak, the current decreases again.9 For a reversible reduction process, the peak current ip (A) is expressed by Eq. (5.26), where D and C are the diffusion coefficient (cm2 s 1) and the concentration (mol cm-3) of the electroactive species ... 

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