Volta potential. ..

Fig. 3.5 The significance of the contact potential (Volta potential difference) Apijj between two metals in contact. (According to S. Trasatti and R. Parsons)... 

In the second step the charge arrives at the internal phase passing through the interface. The associated potential is known as the surface potential jump (also called surface potential, surface electrical potential, etc.). It is determined by dipoles aligned at the interface and by surface charges. It is not identical with the Volta potential difference (also sometimes called the surface potential) that has so far been used for the description of the electrical double layer. For the treatment of the electrical double layer, dipoles did not play a role. In particular in water, however, the aligned water molecules contribute substantially to the surface potential jump x- The Galvani potential, Volta potential, and surface potential jump are related by... 

This is not the only possibility for obtaining an estimate of the absolute SHE potential from electrochemical experiment. As shown in [7], the absolute SHE potential can also be determined from measurements of the potential of zero charge and contact potential (Volta potential difference) of the interface of an inert metal electrode, such as Hg with an electrolytic solution. Surveying the experimental data available at the time Trasatti decided that (abs) = 4.44 V is the best estimate. This value was accepted by lUPAC as their recommended value. Fawcett has recently reviewed the procedure, also taking into account experimental data from mass spectroscopy experiments." His conclusion was that only a small adjustment was necessary (from 4.44 to 4.42 V). 

IV. Electrostatic Potentials Galvani Potential, Volta Potential, Surface Potential... 

IV. ELECTROSTATIC POTENTIALS GALVANI POTENTIAL, VOLTA POTENTIAL, SURFACE POTENTIAL... 

Fig. 7.3 The relationship between the parameters work function (w), Galvani potential (( ), Volta potential ip) and surface potential (x) and work function, electron affinity (A) and ionization energy (I) for metal (left) and semiconductor (right). Evac is the energy of the electron in vacuum immediately in front of the surface. Note that the difference between I and A corresponds to the band gap (internal redox disproportionation, cf. Section 2.1.3). A and I refer to the band edges (standard states) while w refers to Ep, that is, also takes account of the configuration entropy. Please do not confuse the symbol for energy with the symbol E used in the text for EMF. Also remember that at finite temperatures local entropy eflfects are to be considered and hence the free energy must be addressed [537],...

A second type of measurement that may be made on films, usually in conjunction with force-area measurements is that of the contact or surface potential. One essentially measures the Volta potential between the surface of the liquid and that of a metal probe. 

Fig. V-15. Volta potentials Galvani potentials 0, and surface potential jumps x in a two-phase system. (From Ref. 187.)...

Finally, the difference in Volta potential between two phases is the surface potential AV discussed in Chapter III ... 

B. Volta Potentials, Surface Potential Differences, and the Thermionic Work Function... 

The difference in Volta potential AV, which has been called the surface (or contact) potential in this book, is then given by... 

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... 

Time interval, characteristic T, T Volta potential difference ... 

Cell Volta.ge a.ndIts Components. The minimum voltage required for electrolysis to begin for a given set of cell conditions, such as an operational temperature of 95°C, is the sum of the cathodic and anodic reversible potentials and is known as the thermodynamic decomposition voltage, is related to the standard free energy change, AG°C, for the overall chemical reaction,... 

Figure 23. Plot of the experimental contact (Volta) potential difference atmetal/solventinterfaces ( r=0)vs. the values calculated by Jaworski898 as a function of solvent donor (DN) and acceptor (AN) numbers using the equation = 0.007 AN - 0.011 DN - 0.485. (Reproduced from...

Work Function, Fermi Level, Vacuum Level, Galvani and Volta Potentials, Dipole Moments... 

Figure 5.7. Schematic representation of the definitions of work function O, chemical potential of electrons i, electrochemical potential of electrons or Fermi level p = EF, surface potential %, Galvani (or inner) potential

Therefore it is much more useful to use the second way of splitting the energy difference between zero and p, which is common in the area of surface science, i.e. to consider -p as the sum of the work function vacuum level of the surface under consideration ... 

As previously noted the work function O is the work required to bring an electron from the Fermi level of the metal to a point outside the metal where the image forces are negligible, i.e., typically 1 to 0.1 pm outside the metal surface.9,10,16 22 The Volta potential at this point is defined so that the energy required to bring an electron from that point to an "infinite" distance from the metal surface is e. ... 

It must be emphasized that Equations (5.24) and (5.25) stem from the definitions of Fermi level, work function and Volta potential and are generally valid for any electrochemical cell, solid state or aqueous. We can now compare these equations with the corresponding experimental equations (5.18) and (5.19) found to hold, under rather broad temperature, gaseous composition and overpotential conditions (Figs. 5.8 to 5.16), in solid state electrochemistry ... 

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