Work function of gold

Malicki M, Guan Z, Ha SD, Heimel G, Barlow S, Rumi M, Kahn A, Marder SR (2009) Preparation and characterization of 4 -donor substituted stilbene-4-thiolate monolayers and their influence on the work function of gold. Langmuir 25(14) 7967-7975... 

Finally, Fig. 3.18 illustrates the effect of the work function on the width of UPS spectra. Silver has a lower work function (4.72 eV) than ruthenium (5.52 eV), and consequently the width of the spectra increases from 15.7 eV for Ru (001) to 16.7 eV for a thick Ag film, in agreement with (3-11). The work function of gold, however, is almost equal to that of Rh (001). 

R. Bouwman and W. H. M. Sachtler, Photoelectric determination of the work function of gold-platinum alloys, J. Catal. 19, 127 (1970). 

Schwab and co-workers (5-7) found a parallel between the electron concentration of different phases of certain alloys and the activation energies observed for the decomposition of formic acid into H2 and CO2, with these alloys as catalysts. Suhrmann and Sachtler (8,9,58) found a relation between the work function of gold and platinum and the energy of activation necessary for the decomposition of nitrous oxide on these metals. C. Wagner (10) found a relation between the electrical conductivity of semiconducting oxide catalysts and their activity in the decomposition of N2O. 

When light of frequency equal to 2.11 X 10 s shines on the surface of gold metal, the kinetic energy of ejected electrons is found to be 5.83 X 10" J. What is the work function of gold ... 

Figure 8.9 Energy levels and molecular structures of P3HTand [60]PCBM, relative to the vacuum level and the work function of gold.

The above arguments clearly demonstrate the effect of changing metal work function on the measured binding energy. It is now clear why this difference in work function of gold... 

The work function of gold, a parameter which is of interest in the context of its use in electronic devices, is usually given in the range 4.8-5.S eV [14] with 5.3 eV a representative value for use in molecular electronic systems [43]. However, it is worth noting that this figure can be modified by up to 2 eV either way by the attachment of a self-assembled monolayer [43,44]. 

Figure 9-19. Bund diagram of LPPP with hole traps and gold electrodes with Va<- vacuum level. Ec conduction band, Eva valence band. E, Fermi level. . baudgup energy. and , " trap depths. ,( ) trap distribution, X electron affmity, and All work function of the gold electrodes.

Emersion has been shown to result in the retention of the double layer structure i.e, the structure including the outer Helmholtz layer. Thus, the electric double layer is characterised by the electrode potential, the surface charge on the metal and the chemical composition of the double layer itself. Surface resistivity measurements have shown that the surface charge is retained on emersion. In addition, the potential of the emersed electrode, , can be determined in the form of its work function, , since and represent the same quantity the electrochemical potential of the electrons in the metal. Figure 2.116 is from the work of Kotz et al. (1986) and shows the work function of a gold electrode emersed at various potentials from a perchloric acid solution the work function was determined from UVPES measurements. The linear plot, and the unit slope, are clear evidence that the potential drop across the double layer is retained before and after emersion. The chemical composition of the double layer can also be determined, using AES, and is consistent with the expected solvent and electrolyte. In practice, the double layer collapses unless (i) potentiostatic control is maintained up to the instant of emersion and (ii) no faradaic processes, such as 02 reduction, are allowed to occur after emersion. 

The work function of electrodes emersed from aqueous solutions in ultra high vacuum (UHV) can be measured by means of the ultra-violet photo-electron emission spectroscopy (UPS) [KOtz-Neff-MUller, 1986]. Figure 4-27 shows the work function measured by UPS of the emersed metal electrodes of gold,... 

This mechanism requires binding of metal electrons to the chemisorbed molecule without formation of a chemical bond (oxidation). The work function of the metal must be of medium height if the most favorable activation of the N2O decomposition is desired. The energy of activation on gold ( = 4.71 volts) is 29.0 kcal, but on platinum ( = 5.36 volts) 32.5 kcal., according to Hinshelwood and Prichard (69). The relative increase of the energy of activation (12.1%) from platinum to gold is about the same as that of the work function (13.8%). 

However, equation (3) still contains two unknowns the work function of the metal and the work function of the gold deposit. A multilaboratory study has shown that neither carbon nor gold provide a suitable internal standard for catalyst supports (34). Alternatively, the binding energy scale has been referenced to a core level of the support metal cation, for example, the Si 2p peak of silica. This is no improvement. The work function of a high surface area, amorphous catalyst support has never been measured. 

Some of these applications have already been reahzed, and a part of them is even in commercial use. The respective diamond films may or may not be doped. One of the major problems in the application of diamond components is contacting them. The contact points are normally generated by applying metals with a large electron work function Uke gold or platinum, so in parts very high barriers arise at these positions. They mean a serious limitation to the components operability. 

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