Silver, binding energy

Figure 2.10 (a) Molecular structure and atomic numbering of adenine, (b) The calculated model of the adenine-silver quadrimer complex, (c) The calculated frequency shifts /Irbm of the Ad-N3 Ag quadrimer and the calculated binding energy as a function of the bond distance for the Ag-N linkage. 

Room temperature deposition of silver on Pd(lOO) produces a rather sharp Ag/Pd interface [62]. The interaction with a palladium surface induces a shift of Ag 3d core levels to lower binding energies (up to 0.7 eV) while the Pd 3d level BE, is virtually unchanged. In the same time silver deposition alters the palladium valence band already at small silver coverage. Annealing of the Ag/Pd system at 520 K induces inter-diffusion of Ag and Pd atoms at all silver coverage. In the case when silver multilayer was deposited on the palladium surface, the layered silver transforms into a clustered structure slightly enriched with Pd atoms. A hybridization of the localized Pd 4d level and the silver sp-band produces virtual bound state at 2eV below the Fermi level. 

ZnO (suspension) sensitizes the photoreduction of Ag" by xanthene dyes such as uranin and rhodamine B. In this reaction, ZnO plays the role of a medium to facilitate the efficient electron transfer from excited dye molecules to Ag" adsortei on the surface. The electron is transferred into the conduction band of ZnO and from there it reacts with Ag. In homogeneous solution, the transfer of an electron from the excited dye has little driving force as the potential of the Ag /Ag system is —1.8 V (Sect. 2.3). It seems that sufficient binding energy of the silver atom formed is available in the reduction of adsorbed Ag" ions, i.e. the redox potential of the silver couple is more positive under these circumstances. 

Figure 2-7. Origins of the increased O2 binding energy in IPNS when the protein is included in an ONIOM model. (A) A comparison of the optimized geometries from an active-site model (silver) and an ONIOM protein model (dark grey), show that the artificial structural relaxation of the active-site model is more pronounced for the reactant state than for the product state. (B) Contributions to O2 binding from the surrounding protein, evaluated only at the MM level (Adapted from Lundberg and Morokuma [26], Reprinted with permission. Copyright 2007 American Chemical Society.)...

Figure 3.6 XPS spectra of the valence bands of rhodium and silver. The Fermi level, the highest occupied level of a metal, is taken as the zero of the binding energy scale. Rhodium is a d-metal, meaning that the Fermi level lies in the d-band, where the density of states is high. Silver, on the other hand, is an s-metal. The d-band is completely filled and the Fermi level lies in the s-band where the density of states is low. The onset of photoemission at the Fermi level can just be observed. 

Figure 3.15 O Is / Ag 3d5/2 XPS intensity ratio as a function of take-off angle for two oxygen species on polycrystalline silver. The data corresponding to an O 1 s binding energy of 528.4 eV are attributed to subsurface oxygen in Ag, the other with a binding energy of 530.5 eV to oxygen atoms adsorbed on the Ag surface (data from Baschenko et al. (39J).

Figure 6.25. Valence band photoemission spectra of 1 ML Ceo on a Ag(lOO) surface as a function of potassium doping. Also shown are the spectra of the clean Ag(lOO) surface and of a Ceo multilayer (bottom). All binding energies are referred to the L f of polycrystalline silver. Reprinted from Surface Science, Vols. 454-456, C. Cepek, M. Sancrotti, T. Greber and J. Osterwalder, Electronic structure of K doped Ceo monolayers on Ag(OOl), 467 71, Copyright (2000), with permission from Elsevier.

The nature of bonding of the adsorbed species to the model cluster of metal surfaces can be analyzed in terms of the so-called constrained space orbital variation (CSOV) method. For halogen anions adsorbed on various silver surfaces, it has been found that Pauli repulsion, metal polarization, and charge transfer to the metal surface mainly contribute to the binding energy of the ions [104, 301]. 

Table 21 Silver 3d and Nitrogen la Binding Energies (eV) for Silver(I) Complexes of bipy and phen92...

Table 65 X-Ray Photoelectron Data on 3d Binding Energies for Silver(II) Pyridinedicarboxylates92...

Complexing silver with TPP or OEP caused small but noticeable chemical shifts in the binding energy of the Ag, C and N peaks.555 Weak N Is satellites have also been observed in the X-ray photoelectron spectra.556... 

Silver(n) and Silvery hi).—The cationic complex bis-(2,2, 2"-terpyridyl)Ag2+ has been isolated as its peroxydisulphate salt.217 The presence of a d-+d band at 15600 cm-1 is indicative of a six-co-ordinate ion. X-ray photoelectron spectra have provided Ag(3d5/2>3/2) binding energies for this complex and the mono-terpy complex. The influence of pyridine and 2-, 3-, and 4-picoline on bis(diethyl dithio-carbamato)AgH has been examined by e.s.r. spectroscopy.218 The results indicate formation of mono-addition products and the spin hamiltonian parameters for these complexes have been determined. 

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