Understanding surface core-level shifts using the Auger parameter: A study of Pd atoms adsorbed on ultrathin SiO<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mrow /><mml:mn>2</mml:mn></mml:msub></mml:math>films

Kaden, William E.; Büchner, Christin; Lichtenstein, Leonid; Stuckenholz, Stefanie; Ringleb, Franziska; Heyde, Markus; Sterrer, Martin; Freund, Hans‐Joachim; Giordano, Livia; Pacchioni, Gianfranco; Nelin, Connie J.; Bagus, Paul S.

doi:10.1103/physrevb.89.115436

Cited by 39 publications

(40 citation statements)

References 45 publications

(70 reference statements)

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“…[75][76][77][78][79]97,98 For example, Auger parameter analysis for Pd atoms deposited on SiO 2 indicates that the final state is destabilized by ∼0.8 eV compared to bulk Pd. 36 The Pd 3d BEs for our samples are ∼336 eV, which is only ∼0.7 eV higher than the bulk value. 96 The smaller-thanexpected shift suggests, therefore, that there is significant electron transfer from alumina to Pd 20 , partially canceling the shifts expected from the alumina surface potential and final state effects.…”

Section: Articlementioning

confidence: 96%

Effects of Alumina Thickness on CO Oxidation Activity over Pd₂₀/Alumina/Re(0001): Correlated Effects of Alumina Electronic Properties and Pd₂₀Geometry on Activity

2015

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The CO oxidation activity of size-selected Pd 20 clusters deposited on alumina films grown on Re(0001) is shown to depend strongly on the film thickness in the 0 to 10 nm range. For the reaction conditions of these experiments, binding and activation of O 2 is shown to be the limiting process, which can be varied by a factor of 2 by tuning the alumina film thickness, due to effects on both the electronic structure of the alumina film and the morphology of the supported Pd clusters. The alumina films are shown to be doped with Re atoms diffusing from the Re(0001) substrate, leading to a strong dependence of the surface electronic properties on alumina thickness, which in turn, results in the observed thickness-dependent activity of the Pd 20 .

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Section: Articlementioning

confidence: 96%

Effects of Alumina Thickness on CO Oxidation Activity over Pd₂₀/Alumina/Re(0001): Correlated Effects of Alumina Electronic Properties and Pd₂₀Geometry on Activity

2015

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“…We should point out that the importance of initial and final state contributions has been differently assigned for different systems. 20,21 While it is beyond the scope of this paper to cite all of the extensive literature on the decomposition into initial and final state effects, we show that its use is still important for the analysis of the meaning of XPS BE shifts by citing the 2014 paper of Kaden et al 22 The experiment and the theory in this paper make use of an Auger parameter, which can be used to separate initial and final state contributions to ∆BE directly from experimental Auger and XPS data. The Auger parameter was first introduced by Wagner 23-25 to enable separation of these effects when theoretical studies were not available and has since been modified by others, see, for example, Ref.…”

Section: Introductionmentioning

confidence: 97%

Prediction of core level binding energies in density functional theory: Rigorous definition of initial and final state contributions and implications on the physical meaning of Kohn-Sham energies

Bellafont

Bagus

Illas

2015

The Journal of Chemical Physics

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127

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A systematic study of the N(1s) core level binding energies (BE's) in a broad series of molecules is presented employing Hartree-Fock (HF) and the B3LYP, PBE0, and LC-BPBE density functional theory (DFT) based methods with a near HF basis set. The results show that all these methods give reasonably accurate BE's with B3LYP being slightly better than HF but with both PBE0 and LCBPBE being poorer than HF. A rigorous and general decomposition of core level binding energy values into initial and final state contributions to the BE's is proposed that can be used within either HF or DFT methods. The results show that Koopmans' theorem does not hold for the Kohn-Sham eigenvalues. Consequently, Kohn-Sham orbital energies of core orbitals do not provide estimates of the initial state contribution to core level BE's; hence, they cannot be used to decompose initial and final state contributions to BE's. However, when the initial state contribution to DFT BE's is properly defined, the decompositions of initial and final state contributions given by DFT, with several different functionals, are very similar to those obtained with HF. Furthermore, it is shown that the differences of Kohn-Sham orbital energies taken with respect to a common reference do follow the trend of the properly calculated initial state contributions. These conclusions are especially important for condensed phase systems where our results validate the use of band structure calculations to determine initial state contributions to BE shifts.

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“…Details are described in the literature. 181,199,200 Since the relaxation energy may be calculated from this relation in a straightforward manner and the difference in binding energy is the difference between the initial state shifts, i.e. the difference in the Koopmans energies of the involved level, the initial state shift may be extracted.…”

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confidence: 99%

Controlling the charge state of supported nanoparticles in catalysis: lessons from model systems

2018

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Model systems are very important to identify the working principles of real catalysts, and to develop concepts that can be used in the design of new catalytic materials. In this review we report examples of the use of model systems to better understand and control the occurrence of charge transfer at the interface between supported metal nanoparticles and oxide surfaces. In the first part of this article we concentrate on the nature of the support, and on the basic difference in metal/oxide bonding going from a wide-gap non-reducible oxide material to reducible oxide semiconductors. The roles of oxide nanostructuring, bulk and surface defectiveness, and doping with hetero-atoms are also addressed, as they are all aspects that severely affect the metal/oxide interaction. Particular attention is given to the experimental measures of the occurrence of charge transfer at the metal/oxide interface. In this respect, systems based on oxide ultrathin films are particularly important as they allow the use of scanning probe spectroscopies which, often in combination with other measurements and with first principles theoretical simulations, allow full characterization of small supported nanoparticles and their charge state. In a few selected cases, a precise count of the electrons transferred between the oxide and the supported nanoparticle has been possible. Charge transfer can occur through thin, two-dimensional oxide layers also thanks to their structural flexibility. The flow of charge through the oxide film and the formation of charged adsorbates are accompanied in fact by a substantial polaronic relaxation of the film surface which can be rationalized based on electrostatic arguments. In the final part of this review the relationships between model systems and real catalysts are addressed by discussing some examples of how lessons learned from model systems have helped in rationalizing the behavior of real catalysts under working conditions.

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Understanding surface core-level shifts using the Auger parameter: A study of Pd atoms adsorbed on ultrathin SiO2films

Cited by 39 publications

References 45 publications

Effects of Alumina Thickness on CO Oxidation Activity over Pd₂₀/Alumina/Re(0001): Correlated Effects of Alumina Electronic Properties and Pd₂₀Geometry on Activity

Effects of Alumina Thickness on CO Oxidation Activity over Pd₂₀/Alumina/Re(0001): Correlated Effects of Alumina Electronic Properties and Pd₂₀Geometry on Activity

Prediction of core level binding energies in density functional theory: Rigorous definition of initial and final state contributions and implications on the physical meaning of Kohn-Sham energies

Controlling the charge state of supported nanoparticles in catalysis: lessons from model systems

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Understanding surface core-level shifts using the Auger parameter: A study of Pd atoms adsorbed on ultrathin SiO2films

Cited by 39 publications

References 45 publications

Effects of Alumina Thickness on CO Oxidation Activity over Pd20/Alumina/Re(0001): Correlated Effects of Alumina Electronic Properties and Pd20Geometry on Activity

Effects of Alumina Thickness on CO Oxidation Activity over Pd20/Alumina/Re(0001): Correlated Effects of Alumina Electronic Properties and Pd20Geometry on Activity

Prediction of core level binding energies in density functional theory: Rigorous definition of initial and final state contributions and implications on the physical meaning of Kohn-Sham energies

Controlling the charge state of supported nanoparticles in catalysis: lessons from model systems

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Effects of Alumina Thickness on CO Oxidation Activity over Pd₂₀/Alumina/Re(0001): Correlated Effects of Alumina Electronic Properties and Pd₂₀Geometry on Activity

Effects of Alumina Thickness on CO Oxidation Activity over Pd₂₀/Alumina/Re(0001): Correlated Effects of Alumina Electronic Properties and Pd₂₀Geometry on Activity