Frank M. F. de Groot

Utrecht University

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Bert M. Weckhuysen

Utrecht University

Pieter Glatzel

European Synchrotron Radiation Facility

Hebatalla Elnaggar

Institut de minéralogie, de physique des matériaux et de cosmochimie

Ru‐Pan Wang

Universität Hamburg

J. C. Fuggle

Radboud University Nijmegen

Matti M. van Schooneveld

Utrecht University

Piter S. Miedema

Deutsches Elektronen-Synchrotron DESY

Ingmar Swart

Utrecht University

Mario Ulises Delgado‐Jaime

Universidad de Guadalajara

G. A. Sawatzky

University of British Columbia

Cooperative Institutions

Utrecht University

172

Centre National de la Recherche Scientifique

168

Lawrence Berkeley National Laboratory

155

European Synchrotron Radiation Facility

SLAC National Accelerator Laboratory

Helmholtz-Zentrum Berlin für Materialien und Energie

Paul Scherrer Institute

Deutsches Elektronen-Synchrotron DESY

University of California, Berkeley

Stanford Synchrotron Radiation Lightsource

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Comment on “Spin crossover in (Mg,Fe)O: A Mössbauer effect study with an alternative interpretation of x-ray emission spectroscopy data”

Physical Review B (2007)

György Vankó Frank M. F. de Groot

In a recent paper, Kantor et al. presented M\"ossbauer spectroscopy data on the pressure dependence of the Fe spin state in ${\mathrm{Mg}}_{1\ensuremath{-}x}{\mathrm{Fe}}_{x}\mathrm{O}$ [Phys. Rev. B 73, 100101(R) (2006)] and found that the transition was completed at significantly higher pressures than what had been found by x-ray emission spectroscopy (XES) studies. In order to account for the discrepancy, the authors reanalyzed the XES spectra using a simple spectral decomposition and achieved good agreement for the two types of data. In this paper, we show that the proposed alternative analysis of the XES spectra is inadequate, prove that previous XES work had correctly identified the low-spin state at the highest pressures, and provide a complete reanalysis of the XES data.

Spin Crossover

Spin states

10.1103/physrevb.75.177101

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Citations (18)

Oxygen 1sx-ray absorption of tetravalent titanium oxides: A comparison with single-particle calculations

Physical review. B, Condensed matter (1993)

Frank M. F. de Groot J. Faber J. J. M. Michiels M. T. Czyżyk M. Abbate

The oxygen 1s x-ray-absorption spectra of ${\mathrm{SrTiO}}_{3}$ and ${\mathrm{TiO}}_{2}$, in both the rutile and anatase crystal structure, are analyzed using the oxygen p-projected density of states of ground-state band-structure calculations. Good agreement is found and it is concluded that multielectron effects, transition matrix elements, and the core-hole potential present only small, largely undetectable, influences on the spectral shape. From the site- and symmetry-projected density of states the rutile peaks could be assigned to the 3d band (4--8 eV), antibonding oxygen 2p states (10--18 eV), and the titanium 4sp band (20--25 eV). For anatase the titanium 4sp band is shifted to lower energy by about 5 eV, which can be related to the lower density of anatase. From differences in the crystal structure it is argued that the core-hole potential is considerably more effective in perovskite ${\mathrm{SrTiO}}_{3}$ than in both ${\mathrm{TiO}}_{2}$ crystal structures. This is in accordance with the experimental findings.

Rutile

Antibonding molecular orbital

Crystal (programming language)

Density of states

10.1103/physrevb.48.2074

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Citations (275)

Manganese promotion in cobalt-based Fischer-Tropsch catalysis

Studies in surface science and catalysis (2004)

Fernando Morales Cano O.L.J. Gijzeman Frank M. F. de Groot Bert M. Weckhuysen

Fischer–Tropsch process

10.1016/s0167-2991(04)80063-6

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Citations (30)

X‐Ray Absorption Near Edge Spectroscopy

ChemInform (2005)

Frank M. F. de Groot Axel Knop‐Gericke Thorsten Ressler Jeroen A. van Bokhoven

Abstract For Abstract see ChemInform Abstract in Full Text.

Absorption edge

10.1002/chin.200522297

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Citations (3)

2p3s3p,2p3p3p,and Physical review. B, Condensed matter (1999)

Marco Finazzi N. B. Brookes Frank M. F. de Groot

We have investigated the behavior of the $2p3s3p,$ $2p3p3p,$ and $2p3s3s$ Auger lines of NiO, a model compound in the class of strongly correlated $3d$ systems, while varying the photon energy across the Ni ${L}_{3}$ and ${L}_{2}$ absorption edges. The experimental data are discussed in comparison with a theoretical model based on a charge-transfer multiplet approach. When the excitation energy is below the ${L}_{3}$ resonance, we observe the $2p3p3p$ and $2p3s3p$ peaks at a constant binding energy. This behavior is typical of nonradiative resonant Raman scattering. If the photon energy is increased further, the $2p3p3p$ and $2p3s3p$ lines rapidly transform into constant kinetic energy features, showing a normal Auger behavior. The transition from Raman- to Auger-like behavior takes place for photon energies lower than the ones corresponding to excitations of the photoelectron into ligand-hole states. This might indicate the participation of inelastic processes in the recombination of the core hole involving energies much smaller than the NiO gap, or the possible presence of nonlocal effects. On the high photon energy side of the ${L}_{3}$ edge, the constant kinetic energy of the $2p3p3p$ and $2p3s3p$ peaks is systematically larger than the one observed for an excitation well above the ${L}_{2,3}$ edges. We attribute this behavior to the intervention of an intermediate state of ${2p}^{5}{3d}^{10}$ character, which has very little weight but is strongly enhanced at resonance.

Multiplet

Photon energy

10.1103/physrevb.59.9933

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Citations (41)

In situ X‐Ray Absorption of Co/Mn/TiO₂ Catalysts for Fischer—Tropsch Synthesis.

ChemInform (2004)

Fernando Morales Frank M. F. de Groot Pieter Glatzel Evgueni Kleimenov Hendrik Bluhm

10.1002/chin.200450014

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Citations (2)

Nano‐Size Effects on Decay Dynamics of Photo‐Excited Polarons in CeO₂

Advanced Optical Materials (2024)

Abhishek Katoch Sang Han Park Kwangsik Jeong Masoud Lazemi Ru‐Pan Wang

Abstract The study of polaron dynamics in complex materials has garnered significant attention owing to its implications for various technological applications, including catalysis, solid‐state devices, and energy storage. This paper investigates the photo‐excited electron and hole polaron dynamics in cerium dioxide (CeO 2 ) using time‐resolved X‐ray absorption spectroscopy, with an emphasis on the nano‐size effect. Additionally, density functional theory and multiplet calculations have been utilized to reveal the photo‐excited polaron dynamics in CeO 2 single crystal (SC) and nanocrystal (NC). The electron polaron is observed to decay into a deep trap site with a short duration of ≈5 ps, while electrons in the traps stay for more than 1400 ps. The most significant observation is the behavior of holes in NC, which tends to stay longer (≈150 ps) compared to SC (<10 ps) suggesting hole existence more at the surface than at bulk. The fast dissociation of the electron polarons the prolonged lifetime of the electrons above the Fermi level and the enhanced hole lifetime at the surface are proposed to be among the various factors that influence the high reactivity of CeO 2 .

Dynamics

10.1002/adom.202401386

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Citations (0)

Angular dependence of core hole screening inLiCoO2: ADFT+Ucalculation of the oxygen and cobalt Physical Review B (2010)

Amélie Juhin Frank M. F. de Groot György Vankó Matteo Calandra Christian Brouder

Angular-dependent core hole screening effects have been found in the cobalt $K$-edge x-ray absorption spectrum of ${\text{LiCoO}}_{2}$, using high-resolution data and parameter-free general gradient approximation plus $U$ calculations. The $\text{Co}\text{ }1s$ core hole on the absorber causes strong local attraction. The core hole screening on the cobalt nearest-neighbors induces a 2 eV shift in the density of states with respect to the on-site $1s\text{\ensuremath{-}}3d$ transitions, as detected in the $\text{Co}\text{ }K$ pre-edge spectrum. Our density functional theory plus $U$ calculations reveal that the off-site screening is different in the out-of-plane direction, where a 3 eV shift is visible in both calculations and experiment. The detailed analysis of the inclusion of the core hole potential and the Hubbard parameter $U$ shows that the core hole is essential for the off-site screening while $U$ improves the description of the angular-dependent screening effects. In the case of oxygen $K$ edge, both the core hole potential and the Hubbard parameter improve the relative positions of the spectral features.

10.1103/physrevb.81.115115

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Citations (97)

Quanty4RIXS: a program for crystal field multiplet calculations of RIXS and RIXS–MCD spectra usingQuanty

Journal of Synchrotron Radiation (2018)

P. Zimmermann Robert J. Green M. W. Haverkort Frank M. F. de Groot

Some initial instructions for the Quanty4RIXS program written in MATLAB ® are provided. The program assists in the calculation of 1 s 2 p RIXS and 1 s 2 p RIXS–MCD spectra using Quanty . Furthermore, 1 s XAS and 2 p 3 d RIXS calculations in different symmetries can also be performed. It includes the Hartree–Fock values for the Slater integrals and spin–orbit interactions for several 3 d transition metal ions that are required to create the .lua scripts containing all necessary parameters and quantum mechanical definitions for the calculations. The program can be used free of charge and is designed to allow for further adjustments of the scripts.

Multiplet

10.1107/s1600577518004058

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Citations (11)

CCDC 1427488: Experimental Crystal Structure Determination

The Cambridge Structural Database (2015)

Eugenio Coronado M.C. Gimenez-Lopez Tomasz Korzeniak G. G. Levchenko Francisco M. Romero

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

10.5517/cc1jxf0w

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Citations (0)