Charge redistribution in Au-Ag alloys from a local perspective

Tyson, Cashmeira-Dove; Bzowski, A.; Kristof, P.; Kühn, M.; Sammynaiken, Ramaswami; Sham, Tsun‐Kong

doi:10.1103/physrevb.45.8924

Cited by 105 publications

(88 citation statements)

References 22 publications

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“…19−21 Tyson and co-workers investigated Au x Ag y alloy foils with the data from X-ray absorption near-edge structure (XANES) in the Au L 2,3 -edges and XPS of Ag 3d 5/2 corelevel spectra, and found a d electron transfer from Au to Ag. 22 Other reports also suggest charge depletions of Au 5d and Au 4f in association with s-type charge gain at the Au nucleus in the Au−Ag alloys using XANES, XPS, and/or Mossbauer spectroscopy. 23−27 The influences of Au to the other constituent in bimetallic Au alloys could not be simply explained based on the electronegativity arguments of Pauling.…”

Section: ■ Introductionmentioning

confidence: 95%

X-ray Absorption Near-Edge Structure and X-ray Photoelectron Spectroscopy Studies of Interfacial Charge Transfer in Gold–Silver–Gold Double-Shell Nanoparticles

et al. 2012

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Charge transfer in heteromeric structures such as gold−silver core−shell (Au@ Ag) nanoparticles (NPs) and gold−silver−gold double-shell (Au@Ag@Au) NPs was demonstrated using X-ray absorption near-edge structure (XANES) and X-ray photoelectron spectroscopy (XPS) techniques. XANES analyses confirmed that the d-orbital hole density of the Au atoms increases in the following order: Au foil ≅ Au NPs < Au@Ag NPs < Au@Ag@Au NPs. In conjunction with observed positive and negative shifts in the Au 4f and Ag 3d binding energies in XPS spectra of Au@Ag and Au@Ag@Au NPs, we conclude that d electrons are transferred from Au to Ag in the heteromeric NPs due to the charge compensation mechanism. By taking advantage of the charge transfer phenomenon, one can modify the electronic structure of heteromeric NPs with enhanced chemical stability and optical/electronic properties.

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Section: ■ Introductionmentioning

confidence: 95%

X-ray Absorption Near-Edge Structure and X-ray Photoelectron Spectroscopy Studies of Interfacial Charge Transfer in Gold–Silver–Gold Double-Shell Nanoparticles

et al. 2012

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“…The spectrum of Au III also includes a shoulder at an energy 15 eV (and a broad shoulder 50 eV) higher than that of the edge, whereas the spectrum of Au 0 shows a shoulder at 15 eV and rather intense peaks at 25 and 50 eV higher than that of the edge [41,42]. Although there are only a few reported examples [40,43,44], Au L II -edge XANES spectra have also been used in tandem with Au L III -edge XANES to estimate the oxidation states of gold. In general, both Au L II -and L III -edge XANES spectra of samples containing cationic gold could include white lines, which are indicative of unoccupied density of d states in the vicinity of the Fermi level [44].…”

Section: Methods Of Determination Of Oxidation States Of Gold In Suppmentioning

confidence: 91%

“…In general, both Au L II -and L III -edge XANES spectra of samples containing cationic gold could include white lines, which are indicative of unoccupied density of d states in the vicinity of the Fermi level [44]. In principle, the difference between the intensities of the white lines at the L II -and L III -edges gives a semi-quantitative approximation that can be used to estimate the occupancies of d states, which are related to the oxidation state of the gold [44], but at the current stage of development of the science, we regard the information provided by XANES about oxidation states of gold on supports as being essentially qualitative.…”

Section: Methods Of Determination Of Oxidation States Of Gold In Suppmentioning

confidence: 99%

Role of cationic gold in supported CO oxidation catalysts

2007

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“…5, 6), the absorption regions 1 and 2 indicate the dominance of the Ag substrate. The decreased area under the curve, when compared to the Ag standard, indicates a small concentration of Au alloyed with Ag since the appearance of the Ag XANES is clearly AgAu alloy-like [43]. Both AgCl and AgI were detected with LCF analysis outside of the tarnish location.…”

Section: Xrf and Micro-xanes Analysismentioning

confidence: 90%

Exploring tarnished daguerreotypes with synchrotron light: XRF and μ-XANES analysis

et al. 2018

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We report on the elemental and chemical characterization of tarnish on a historic daguerreotype plate. Scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy reveal the presence of C, O, Na, K, P, Cl, Hg, Ag, Cu, S and Au. Synchrotron based X-ray absorption near edge structure (XANES) spectroscopy, together with two-dimensional X-ray fluorescence (XRF) microscopy, provide information beyond the elemental distribution and speciation of the daguerreian tarnish features, revealing the presence of NaCl, KCl, HgCl 2 , HgSO 4 , CuS, and Ag 2 S on the surface. Through the application of synchrotron XRF, the distributions of Ag and S were found to be inversely correlated. This suggests a preferential accumulation of S within high-density particle regions. Spectroscopic investigation at different regions within the XRF image showed that blemish regions contained degradation products such as NaCl and KCl with AgCl noted in the surrounding regions. The observation of Cu on the surface, in the form of CuS, may either be a result of Cu diffusing through grain boundaries and/or holes in the Ag, or from the accretion of Cu salts, such as basic sodium copper carbonate, from the deterioration of the above cover glass. Silver halides (AgCl, AgBr and AgI) were also detected with XANES. This may be the result of either environmental conditions or from residual products from the production process of the plate. These results point to the interaction between deterioration products from the cover glass with the daguerreotype surface as one, but not the only, source of the tarnish.

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Charge redistribution in Au-Ag alloys from a local perspective

Cited by 105 publications

References 22 publications

X-ray Absorption Near-Edge Structure and X-ray Photoelectron Spectroscopy Studies of Interfacial Charge Transfer in Gold–Silver–Gold Double-Shell Nanoparticles

X-ray Absorption Near-Edge Structure and X-ray Photoelectron Spectroscopy Studies of Interfacial Charge Transfer in Gold–Silver–Gold Double-Shell Nanoparticles

Role of cationic gold in supported CO oxidation catalysts

Exploring tarnished daguerreotypes with synchrotron light: XRF and μ-XANES analysis

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