Oxidized silver, spectra

Giersig et al. have examined [165] the effect of molecular iodine, a strong oxidant, on the absorption spectrum of Ag-Si02 particles. Molecular iodine oxidizes silver according to... 

Figure 8. Valence band XPS (a) and UPS (b) spectra of silver islands on native oxide covered Si(l 0 0) during bombardment with 1 keV Ar" ions. Substrate related contributions are removed. Numbers at each spectra stand for the Ag/Si ratio determined from the appropriate XPS core level spectra. The uppermost curve is the spectrum of polycrystalline bulk Ag. (Reprinted from Ref [146], 1998, with permission from Elsevier.)...

Melroy and co-workers88 recently reported on the EXAFS spectrum of Pb underpotentially deposited on silver (111). In this case, no Pb/Ag scattering was observed and this was ascribed to the large Debye-Waller factor for the lead as well as to the presence of an incommensurate layer. However, data analysis as well as comparison of the edge region of spectra for the underpotentially deposited lead, lead foil, lead acetate, and lead oxide indicated the presence of oxygen from either water or acetate (from electrolyte) as a backscatterer. 

The first report of the SERS spectrum of a species adsorbed at the electrode/ electrolyte interface was by Fleischman et al (1974) and concerned pyridine on silver. The Raman spectrum of the adsorbed pyridine was only observed after repeated oxidation/reduction cycles of the silver electrode, which resulted in a roughened surface. Initially, it was thought that the 106-fold enhancement in emission intensity arose as a result of the substantially increased surface area of the Ag and thus depended simply on the amount of adsorbate. However, Jeanmarie and Van Duync (1977) and Albrecht and Creighton (1977), independently reported that only a single oxidation/reduction cycle was required to produce an intense Raman spectrum and calculations showed that the increase in surface area could not possibly be sufficient to give the observed enhancement. 

Lockyer and Baxcndall1 investigated the arc spectrum of vanadium by volatilising vanadium chloride and vanadium oxide between poles of pure silver. Using a Rowland grating, over 650 lines were obtained in the region between A 3887 and A 4932, the more intense of which arc indicated in the following table —... 

The decrease of the rate of ethene oxide formation with respect to time observed at temperatures >470 K can be explained by the accumulation of oxygen species embedded in the silver surface that decrease the surface area available for the formation of the reactive species. Nucleophilic and electrophilic oxygen, which are the major surface species at 420 K, are still present on the silver surface at 470 K however, they are rapidly removed in the absence of oxygen in the gas phase (see the difference spectrum in Figure 18). 

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