ESCA study of compounds of gold in the oxidation state –1

Knecht, J.; Fischer, Róbert; Overhof, H.; Hensel, F.

doi:10.1039/c39780000905

Cited by 47 publications

(22 citation statements)

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“…There is an additional minority species with a maximum at 85.2 eV (brown curves), which has been observed previously [10]. The major Au 4f 7/2 component can be assigned to metallic Au, while the nature of the minor component is controversial, as various authors have attributed this signal either to Au(I) [10,17,18] or to the finite size of the clusters combined with the insulating nature of the substrate, which results in a less efficient screening of the final core hole [18][19][20][21][22][23] such that the positive Au 4f core-level shift induced by the final state charge outweighs the negative surface atom core-level shift [31]. When this sample was exposed to molecular oxygen (0.1 mbar, Figure 1b) under X-rays for one hour, the main peak shifted by 0.3 eV towards higher binding energy.…”

Section: Resultssupporting

confidence: 55%

“…In our experiments, previously reported Au core level shifts were convincingly reproduced. In addition, we observe the two separate Au 4f core level shifts during a single experiment, unlike previous reports [9][10][11], and show that the 0.9 eV shift, whose origin has been controversially discussed in the literature (Au (I) oxide [17,18] versus final state effects [19][20][21][22][23]) is most likely due to final state effects.…”

Section: Introductioncontrasting

confidence: 72%

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Evidence for an active oxygen species on Au/TiO2(110) model catalysts during investigation with in situ X-ray photoelectron spectroscopy

et al. 2012

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The influence of oxygen (O 2 ) and carbon monoxide (CO) on Au nanoparticles supported on TiO 2 (110) in the size range of 2 to 3 nm has been studied using X-ray photoelectron spectroscopy (XPS) and in-situ (high pressure) XPS at 300 K for O 2 and/or CO pressures of 0.1 to 1 mbar. These experiments were aimed at revisiting Au 4f core level shifts as reported in the literature and most importantly, to establish the dependence of the core-level shifts on the knowledge that there exists a maximum in reactivity for CO oxidation. Two samples were prepared with a coverage corresponding to that maximum (Au coverage 0.14-0.2 ML, particle size ~ 2 nm) while a third sample was expected to be less reactive (Au coverage 0.4 ML, particle size ~ 3 nm). At elevated O 2 pressures, a new component at higher binding energy (+2.4 eV relative to the Au(0) bulk signal) evolved at all particle sizes. Its appearance was attributed to a photoinduced activation of oxygen and a further oxidation of gold. The activation was much more efficient on the 2 nm particles. The relative intensity of the shifted component depended strongly on O 2 pressure and, thus, likely on the coverage; not present in 0.1 mbar O 2 regardless of exposure time and particle size, it dominated the Au 4f spectrum of particles 2 nm in size. This pressure-dependent formation reconciles previously conflicting XPS data. Finally, the oxygen activated species were very reactive toward CO as manifested by the rapid disappearance of the new Au 4f component in a 1:1 mixture of CO and O 2 . The rates of evolution and consumption of this component were found to depend on gold coverage (and thus, particle size) and were highest for the smaller particles.

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Section: Resultssupporting

confidence: 55%

Section: Introductioncontrasting

confidence: 72%

Evidence for an active oxygen species on Au/TiO2(110) model catalysts during investigation with in situ X-ray photoelectron spectroscopy

et al. 2012

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“…The ESCA spectrum of the mixed valence complex is supportive of the presence of the + 1 and + 3 oxidation states. The mixed valence complex produces a Au(4fT/2) line at a binding energy of 87.1 eV which can be assigned to the + 3 oxidation state and another line at 84.9 eV which can be assigned to the + 1 state [7][8][9]. The spectrum of the Au(III) complex, trichloro(dimethyl sulfoxide)Au(III), also has a line at a binding energy of 87.1eV while gold metal, as a reference, has its Au(4fT/2) line at 83.8 eV.…”

Section: Resultsmentioning

confidence: 99%

A mixed valence complex of gold with dimethyl sulfoxide

Schoenfelner

Potts

1981

Journal of Inorganic and Nuclear Chemistry

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equilibrium constant Km of PbHL 2+ among the four amino acids. If the binding of Pb 2. through the carboxylate group occurs in PbHL 2÷, as was suggested previously [l], this trend is consistent with the fact that no difference in proton affinity of the carboxylate groups of the zwitter-ions is observed among the amino acids. On the contrary, it is obvious that the equilibrium constants/31o~ of the three C-substituted derivatives are smaller than that of glycine in spite of the increased basicity (Kt) of the nitrogen in the derivatives compared with glycine.The distribution of the species as a function of -log[H +] calculated at Cpb = 0.005 mol dm 3 and CL = 0.05 mol dm 3 using their constants are drawn in Fig. 5.

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“…Compare, for example, the binding energy of the strong 4f7/2 peak in samples 2-5 with the elemental gold sample. The binding energy of the Au 4f7/2 peak is approximately 85 eV in all gold-doped samples• Comparison of this binding energy with gold compounds [10] and mixed valence gold compounds [11] indicates that the oxidation state of substitutional Au is Au +. The shoulder on the low binding-energy side of the 4f7/z peak (near 83 eV) is most probably due to precipitated Au °.…”

Section: Resultsmentioning

confidence: 99%

Oxidation state and site selection of gold in (YBa2Cu3O7 ??)(1 ? x)Au x

Ganakas

Morgan

Jakovidis

1995

J Mater Sci: Mater Electron

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Recent experiments on the effect of Au substitution on the superconductivity of YBa2Cu307_~ (YBCO) have revealed that Au, unlike most other dopants, enhances the superconducting transition temperature, Tc, by ~ 2 K at 10 mole % Au. In the present study, X-ray photoelectron spectra, nominally of 4, 6, 8 and 10 mole% Au-doped YBCO, have been obtained. The Au spectra display a relatively intense peak which is the oxidized component associated with the Au 4f7/2 core level, and an additional component that is most probably due to unreacted gold. The binding energy of the oxidized component is consistent with Au +. This observation, together with previous studies, leads us to postulate a structural model in which Au ÷ substitutes into a two-ligand c-axis co-ordinated Cu(1) site at a Ba-O (4) surface layer.

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ESCA study of compounds of gold in the oxidation state –1

Abstract: ESCA measurements on a series of gold compounds reveal a monotonic relationship between binding energies of the Au 4f levels and formal oxidation states, and provides first evidence for the oxidation state -1 of gold in CsAu and RbAu.

Cited by 47 publications

References 0 publications

Evidence for an active oxygen species on Au/TiO2(110) model catalysts during investigation with in situ X-ray photoelectron spectroscopy

Evidence for an active oxygen species on Au/TiO2(110) model catalysts during investigation with in situ X-ray photoelectron spectroscopy

A mixed valence complex of gold with dimethyl sulfoxide

Oxidation state and site selection of gold in (YBa2Cu3O7 ??)(1 ? x)Au x

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