Probability density of wave function of excited photoelectron: understanding XANES features

Šipr, O.

doi:10.1107/s0909049500016496

Cited by 6 publications

(6 citation statements)

References 8 publications

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“…26 The XANES intensity is proportional to the probability of absorption of a photon by a core electron. 38 It is reported that the calculated PDOS of O in final state, which includes the core-hole effect, correlates well with the corresponding O K-edge XANES of α-SiO 2 . 39 The PDOS from the ground state calculation is quite different for the PDOS from the final state.…”

Section: Computational Detailssupporting

confidence: 60%

“…As mentioned in Section 2, the XANES intensity is proportional to the probability of absorption of a photon by a core electron. 38 Here, the XANES spectrum is analyzed by comparing it to the PDOS of Cu with a core-hole. Note that it is difficult to evaluate the transition energy by using the pseudopential method, 52 therefore, the transition energy of our Cu K-edge XANES is referenced to the Fermi level.…”

Section: Theoretical K-edge Xanes Of Cu In Cu-ssz-13mentioning

confidence: 99%

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The interaction of reactants, intermediates and products with Cu ions in Cu-SSZ-13 NH₃SCR catalysts: an energetic and ab initio X-ray absorption modeling study

Zhang

Szanyi

Gao

et al. 2016

Catal. Sci. Technol.

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In this contribution, the most likely positions for Cu in Cu-SSZ-13 with a single charge compensating Al atom (ZCu) at a Si:Al ratio of 11:1 was investigated, including the effect of the adsorption of reactants, intermediates, and products that one would find in a NH3 SCR reaction by using first-principles calculations based on density functional theory. The 6-membered ring (6MR) site is the most energetically favorable, while the 8-membered ring (8MR) sites are less favorable with energy differences about 0.5 eV with respect to the 6MR site for plain ZCu. Upon molecular adsorption, the energy differences between Cu in the 8MR and 6MR sites decrease and in some cases almost disappear. For the complex scenarios of NO or CO adsorption, the co-adsorption of 2 NO or 2 CO molecules, as well as NO or CO with OH and H2O, weakens the interaction between adsorbates and Cu. The X-ray absorption near edge structure (XANES) of Cu in Cu-SSZ-13 under different conditions was also modeled from first principles. A small peak feature around 8979.5 eV was found in the Kedge XANES of Cu for a clean ZCu conformation with Cu in an 8MR site while this feature is absent when Cu is in a 6MR site. We correlate this result for this case as well as for other representative configurations by analyzing the corresponding PDOS of the excited state of Cu while taking into account the core-hole effect. Molecular adsorption onto Cu in a 6MR or an 8MR site results in a Cu K-edge XANES that is independent on its location. When NO (or CO, N2) is adsorbed onto Cu in ZCu, a small peak feature in the K-edge XANES appears at 8.98 keV, which is induced by the splitting of the Cu 4p state. An analysis of the XANES in the presence of two co-adsorbed species on an isolated Cu ion shows that the K-edge position of Cu has the following order (from low to high energy): clean < M < M+H2O < 2M < M+OH (M denotes NO or CO). As a result, we conclude: (1) XANES can readily distinguish between adsorbates on ZCu due to their different oxidizing capacities; but (2) XANES cannot be used to distinguish between the Cu location/oxidation state in the presence of adsorbates, except in the presence of H2O and NH3 where such distinctions can be made.

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Section: Computational Detailssupporting

confidence: 60%

Section: Theoretical K-edge Xanes Of Cu In Cu-ssz-13mentioning

confidence: 99%

The interaction of reactants, intermediates and products with Cu ions in Cu-SSZ-13 NH₃SCR catalysts: an energetic and ab initio X-ray absorption modeling study

Zhang

Szanyi

Gao

et al. 2016

Catal. Sci. Technol.

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“…45 for the first time and its detailed description can be found in the paper of Š ipr. 31 We recall its essence only briefly here.…”

Section: Photoelectron Probability Densitymentioning

confidence: 99%

Cu, Fe, and SK- andL-edge XANES spectra ofCuFeS2:Localization and interpretation of pre-peak states

2004

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The pre-peak in the x-ray-absorption near-edge structure ͑XANES͒ of CuFeS 2 is studied by exploring the associated photoelectron probability density as well as by investigating the cluster size effect. All significant features of the Cu, Fe, and S K-edge experimental spectra and of the S L 2,3 -edge spectrum are successfully reproduced by the real-space multiple-scattering ͑RSMS͒ calculations with self-consistent scattering potentials and by full-potential band-structure calculations employing all-electron pseudopotentials. Pre-peak-forming photoelectron states are confined to all Fe sites of the finite cluster involved in the RSMS calculation, not just to that Fe which is the nearest one to the photoabsorbing atom. Different interpretations of the pre-peak can be unified within a single scheme of the photoelectron probability density. In order to achieve a comprehensive understanding of XANES features, both the photoelectron probability density and the cluster size effect ought to be analyzed.

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“…(18) and the amplitudes β (j) L (L ′′ ) from Eq. (13). The angulark-integration in (C1) could be performed analytically in principle.…”

Section: Appendix C: Technical Details Of Pepd Calculationsmentioning

confidence: 99%

Spatial distribution of photoelectrons participating in formation of x-ray absorption spectra

Šipr

2002

Phys. Rev. B

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Interpretation of x-ray absorption near-edge structure (XANES) experiments is often done via analyzing the role of particular atoms in the formation of specific peaks in the calculated spectrum. Typically, this is achieved by calculating the spectrum for a series of trial structures where various atoms are moved and/or removed. A more quantitative approach is presented here, based on comparing the probabilities that a XANES photoelectron of a given energy can be found near particular atoms. Such a photoelectron probability density can be consistently defined as a sum over squares of wave functions which describe participating photoelectron diffraction processes, weighted by their normalized cross sections. A fine structure in the energy dependence of these probabilities can be extracted and compared to XANES spectrum. As an illustration of this novel technique, we analyze the photoelectron probability density at the Ti K pre-edge of TiS 2 and at the Ti K edge of rutile TiO 2 .To be published in Physical Review B, tentatively scheduled for 15 May 2002 issue. 78.70.Dm

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Probability density of wave function of excited photoelectron: understanding XANES features

Cited by 6 publications

References 8 publications

The interaction of reactants, intermediates and products with Cu ions in Cu-SSZ-13 NH₃SCR catalysts: an energetic and ab initio X-ray absorption modeling study

The interaction of reactants, intermediates and products with Cu ions in Cu-SSZ-13 NH₃SCR catalysts: an energetic and ab initio X-ray absorption modeling study

Cu, Fe, and SK- andL-edge XANES spectra ofCuFeS2:Localization and interpretation of pre-peak states

Spatial distribution of photoelectrons participating in formation of x-ray absorption spectra

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Probability density of wave function of excited photoelectron: understanding XANES features

Cited by 6 publications

References 8 publications

The interaction of reactants, intermediates and products with Cu ions in Cu-SSZ-13 NH3SCR catalysts: an energetic and ab initio X-ray absorption modeling study

The interaction of reactants, intermediates and products with Cu ions in Cu-SSZ-13 NH3SCR catalysts: an energetic and ab initio X-ray absorption modeling study

Cu, Fe, and SK- andL-edge XANES spectra ofCuFeS2:Localization and interpretation of pre-peak states

Spatial distribution of photoelectrons participating in formation of x-ray absorption spectra

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The interaction of reactants, intermediates and products with Cu ions in Cu-SSZ-13 NH₃SCR catalysts: an energetic and ab initio X-ray absorption modeling study

The interaction of reactants, intermediates and products with Cu ions in Cu-SSZ-13 NH₃SCR catalysts: an energetic and ab initio X-ray absorption modeling study