X-ray photoemission lineshapes and energies in Pd<sub>x</sub>Cu<sub>1-x</sub>

Sundaram, V. S.; Moraes, Marina Borgert; Rogers, J.D.; Kleiman, G. G.

doi:10.1088/0305-4608/11/5/018

Cited by 37 publications

(10 citation statements)

References 17 publications

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“…6). A similar phenomenon was also observed in several other studies for Pd-Cu alloy systems [28][29][30]. This is due to a strong interaction between palladium and copper in which bonds between "sd" levels of Pd and resonant "dsp" levels of Cu are formed [28].…”

Section: Resultssupporting

confidence: 85%

Electroless plating synthesis, characterization and permeation properties of Pd–Cu membranes supported on ZrO modified porous stainless steel

Gao

Lin

et al. 2005

Journal of Membrane Science

120

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Section: Resultssupporting

confidence: 85%

Electroless plating synthesis, characterization and permeation properties of Pd–Cu membranes supported on ZrO modified porous stainless steel

Gao

Lin

et al. 2005

Journal of Membrane Science

120

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“…With this value of l͞R Eq. (7) predicts a shift in Cu 2p binding energy of up to 1 eV in Cu x Pd 12x alloys, in broad agreement [8] with experiment [9,10]. The inverse lifetime G in the simulations corresponds to that of the Cu 2p 3͞2 level [11].…”

supporting

confidence: 68%

Madelung Potentials and Disorder Broadening of Core Photoemission Spectra in Random Alloys

1997

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We present the first experimental evidence for "disorder broadening" of core level x-ray photoemission line shapes in alloys. The broadening is attributed to variations in electrostatic potential. A model in which the charge on a site is assumed to be proportional to its number of unlike neighbors has recently been shown to greatly improve the calculated total energies of disordered alloys. This model predicts a broadening a factor of 2 larger than observed. We discuss this result in terms of short range order and a generalized charge model. [S0031-9007(97)03188-8] PACS numbers: 79.60.Ht, 71.23. -kSince the work of Madelung [1] the electrostatic energy of arrays of charges has attracted continued attention [2]. However, although the concepts of electronegativity and ionicity have had great historical importance in chemistry, solid state physicists are reluctant to consider "charge transfer" as this does not constitute a quantum mechanical observable and the concept is therefore vague and arbitrary. In recent years the inclusion of Madelung energies for disordered systems, previously assumed to be zero, has been shown to be essential to a truly ab initio description of the physical and electronic structure of random alloys [3,4], forcing a reexamination of the charge transfer picture. In particular, a model in which the charge on a site is determined by the local composition has gained increasing support [3][4][5] and has been used [6] to explain the structural stability of a wide range of compounds and alloys.In this Letter we present the first experimental study of the Madelung potential in random alloys. One expects that variation in local bonding configuration will give a distribution of potentials, but no such "disorder broadening" has previously been observed with core level x-ray photoelectron spectroscopy (XPS). We estimate the magnitude of disorder effects and present high resolution experimental data showing the first observation of disorder broadening in the core level XPS of random alloys. This comparison of theory and experiment goes to the heart of our understanding of the electronic structure and bonding in alloys, giving insight into local charge neutrality, short range order, and charge correlation.The electrostatic potential at lattice point i in a random alloy relative to the corresponding elemental solid can be expressed as a sum of intra-atomic and Madelung potentials,.(1)If Q is measured in units of e, the electronic charge, and the nearest neighbor distance R is in Å, then the potential is in volts. (We suppress the 14.4 factor in subsequent equations for brevity.) The first summation in the Madelung term is over concentric spheres with radius Rr m centered on site i, and the second is over the Z m sites in the mth shell. To characterize the distribution of potentials we first require a model for the charges Q i at each site. One may suppose that the Q i are determined by c i , the composition fraction for the species type at that site. For a random binary alloy A x B 12x charge neutrality r...

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“…With increasing ion beam exposure ͑each scan was 50 s͒, the higher kinetic energy peak, attributed to Pd, begins to grow as the lower kinetic energy peak, which arises from Cu, begins to decrease. 7 The Cu 2 p 3/2 BE for the bulk ͑10.0 ML͒ is 932.50 eV. III B.͒ Even at this relatively low beam energy, it can clearly be seen that the degree of mixing on the surface is increasing as a function of exposure time to the beam.…”

Section: A Ion-beam-induced Alloying Of Cu-pdmentioning

confidence: 94%

Core-level shifts in trimetallic systems

Rainer

Corneille

Goodman

1995

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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High resolution and symmetry resolved corelevel spectroscopy using soft xray undulator (invited) Rev. Sci.Trimetallic systems prepared by the deposition of monolayers of two different metals ͑Cu, Pd, Ag, and Au͒ on a Mo͑110͒ single crystal have been studied using x-ray photoelectron spectroscopy ͑XPS͒ and ion scattering spectroscopy ͑ISS͒. Because the dissimilar second layer can be resolved from the bulk substrate with XPS, this approach allows the core-level shifts ͑CLSs͒ for the first and second layers in the trimetallic system to be measured. ISS was employed to measure the relative surface composition of the sample in order to identify those systems in which no significant mixing of the admetals takes place at room temperature. The Cu/Pd/Mo͑110͒, Au/Pd/Mo͑110͒, and Ag/Cu/ Mo͑110͒ systems were determined to exist as segregated monolayers at room temperature. Initial ISS studies showed that a He ϩ ion beam with an energy of 475 eV was sufficient to induce alloying between Cu and Pd monolayers. The CLSs for the Au/Pd/Mo͑110͒ and Cu/Pd/Mo͑110͒ systems indicate changes in the d-electron populations of Au, Pd, and Cu. In the case of the Cu/Pd/Mo͑110͒, the CLSs cannot be explained in terms of a simple charge transfer between metals.

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X-ray photoemission lineshapes and energies in Pd_xCu_1-x

Cited by 37 publications

References 17 publications

Electroless plating synthesis, characterization and permeation properties of Pd–Cu membranes supported on ZrO modified porous stainless steel

Electroless plating synthesis, characterization and permeation properties of Pd–Cu membranes supported on ZrO modified porous stainless steel

Madelung Potentials and Disorder Broadening of Core Photoemission Spectra in Random Alloys

Core-level shifts in trimetallic systems

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X-ray photoemission lineshapes and energies in PdxCu1-x

Cited by 37 publications

References 17 publications

Electroless plating synthesis, characterization and permeation properties of Pd–Cu membranes supported on ZrO modified porous stainless steel

Electroless plating synthesis, characterization and permeation properties of Pd–Cu membranes supported on ZrO modified porous stainless steel

Madelung Potentials and Disorder Broadening of Core Photoemission Spectra in Random Alloys

Core-level shifts in trimetallic systems

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Product

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X-ray photoemission lineshapes and energies in Pd_xCu_1-x