Electrochemical potential, measurements

Steigerwald JM, Duquette DJ, Murarka SP, Gutmann RJ. Electrochemical potential measurements during the chemical-mechanical polishing of copper thin films. J Electrochem Soc 1995 142(7) 2379-2385. 

An example of the use of Pourbaix diagrams and electrochemical potential measurements is the polish performance of copper in three slurries based upon NH3 compounds. These slurries consist of 2.5 wt% AI2O3 abrasive with an average aggregate size of 300 nm, DI water, and either NIf,OH, NH4NO3, or NH4CI. The total concentration of ammonia (as NH3, NH4 or NH4X) in each... 

From the examples it is apparent that the electrochemical potential measurements during polishing are useful in determining and predicting characteristics of the polish process. Increases in... 

As the electrochemical potential measures the escaping tendency of electrons, the electron-attracting power should be its negative. Hence, electronegativity is defined... 

Figure 3.22 demonstrates the high precision of coulometric titration and the accuracy achievable for thermodynamic data by electrochemical potential measurements. 

The galvanic corrosion behavior can be predicted using polarization behavior. Electrochemical potential measurements... 

Electrochemical Potential Measured at the Tip of a Growing Fatigue Crack in Demineralized Water at 93°C the Effect of Frequency, Wave Form and Oxygen Content... 

When reporting electrochemical potential measurements, it is always important to indicate which reference half-cell was used to carry out the work. This information is required to compare these measurements to similar data that could have been obtained using any other reference half-cell listed in Table 4.7. The scheme presented in Figure 4.3 provides a graphical representation to visualize some of the information listed in Table 4.7. 

Nernst potential Standard electrochemical potential measured with respect to a standard hydrogen... 

It is impossible to build absolute identical silver/silver chloride electrodes. The standard potential difference depends in some unknown way on the method of preparation [11]. For the Ag/AgCl electrodes of the thermo-electrical type [17], the cell potential variations in preparation cause variations in potential in the order of 0.2 mV. The standard potential is therefore determined simultaneously to the electrochemical potentials measured in the primary pH standard buffer solutions. Chloride ions are added to the chloride-free buffer at several chloride molalities in order to stabilize the potential of the silver-silver chloride electrode. The electrochemical cell potential consists merely of the difference in the two electrode potentials [18]. 

In these equations the electrostatic potential i might be thought to be the potential at the actual electrodes, the platinum on the left and the silver on the right. However, electrons are not the hypothetical test particles of physics, and the electrostatic potential difference at a junction between two metals is nnmeasurable. Wliat is measurable is the difference in the electrochemical potential p of the electron, which at equilibrium must be the same in any two wires that are in electrical contact. One assumes that the electrochemical potential can be written as the combination of two tenns, a chemical potential minus the electrical potential (- / because of the negative charge on the electron). Wlien two copper wires are connected to the two electrodes, the... 

If two metals with different work functions are placed m contact there will be a flow of electrons from the metal with the lower work function to that with the higher work fimction. This will continue until the electrochemical potentials of the electrons in the two phases are equal. This change gives rise to a measurable potential difference between the two metals, temied the contact potential or Volta potential difference. Clearly... 

The suitabihty of these chromophores rests in large measure in being able to simultaneously optimize three properties (electrochemical potentials,... 

Because only differences in chemical potential can be measured, the chemical or electrochemical potential of each species is broken down as in equation 3. An arbitrary secondary reference state is defined for each compound. For instance, the chemical potential of chlorine gas is expressed as... 

Evidence of localized corrosion can be obtained from polarization methods such as potentiodynamic polarization, EIS, and electrochemical noise measurements, which are particularly well suited to providing data on localized corrosion. When evidence of localized attack is obtained, the engineer needs to perform a careful analysis of the conditions that may lead to such attack. Correlation with process conditions can provide additional data about the susceptibility of the equipment to locaHzed attack and can potentially help prevent failures due to pitting or crevice corrosion. Since pitting may have a delayed initiation phase, careful consideration of the cause of the localized attack is critical. Laboratory testing and involvement of an... 

Because these stability measurements pertain to the gas phase, it is important to consider the effects that solvation might have on the structure-stability relationships. Hydride affinity values based on solution measurements can be derived from thermodynamic cycles that relate hydrocarbon p T, bond dissociation energy and electrochemical potentials. The hydride affinity, AG, for the reaction... 

For saturated hydrocarbons, exchange is too slow and reference points are so uncertain that direct determination of pAT values by exchange measurements is not feasible. The most useful proach to obtain pK data for such hydrocarbons involves making a measurement of the electrochemical potential for the reaction... 

A study of the electrochemical oxidation and reduction of certain isoindoles (and isobenzofurans) has been made, using cyclic voltammetry. The reduction wave was found to be twice the height of the oxidation wave, and conventional polarography confirmed that reduction involved a two-electron transfer. Peak potential measurements and electrochemiluminescence intensities (see Section IV, E) are consistent vidth cation radicals as intermediates. The relatively long lifetime of these intermediates is attributed to steric shielding by the phenyl groups rather than electron delocalization (Table VIII). 

Pourbaix, M., Recent Applications of Electrode Potential Measurements in the Thermodynamics and Kinetics of Corrosion of Metals , Corros., 25, 267 (1969) de Nora, O., Gallone, P., Traini, C. and Meneghini, G., On the Mechanism of Anodic Chlorate Oxidation , J. Electrochem. Soc., 116, 147 (1969)... 

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