Oxygen<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>K</mml:mi></mml:math>near-edge fine structure: An electron-energy-loss investigation with comparisons to new theory for selected<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mn>3</mml:mn><mml:mi>d</mml:mi></mml:math>Transition-metal oxides

Grunes, L. A.; Leapman, Richard D.; Wilker, Charles N.; Hoffmann, Roald; Kunz, A. Barry

doi:10.1103/physrevb.25.7157

Cited by 337 publications

(157 citation statements)

References 48 publications

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“…The white line is assigned to the O2p-Fe3d band and the broader structure 5-20 eV above the threshold to the O2p-Fe4sp band. This assignment agrees with molecular-orbital calculations [248,[251][252][253]. The broad Fe4sp band at 542 eV also indicates a significant covalent bonding between Fe4sp states and O2p states.…”

Section: Xas Measurementssupporting

confidence: 76%

Surface chemistry and catalysis on well-defined epitaxial iron-oxide layers

Weiß

Ranke

2002

Progress in Surface Science

584

610

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Metal-oxide based catalysts are used for many important synthesis reactions in the chemical industry. A better understanding of the catalyst operation can be achieved by studying elemantary reaction steps on well-defined model catalyst systems. For the dehydrogenation of ethylbenzene to styrene in the presence of steam both unpromoted and potassium promoted iron-oxide catalysts are active. Here we review the work done over unpromoted single-crystalline FeO(111), Fe 3 O 4 (111) and α-Fe 2 O 3 (0001) films grown epitaxially on Pt(111) substrates. Their geometric and electronic surface structures were characterized by STM, LEED, electron microscopy and electron spectroscopic techniques. In an integrative approach, the interaction of water, ethylbenzene and styrene with these films was investigated mainly by thermal desorption and photoelectron emission spectroscopy. The adsorptiondesorption energetics and kinetics depend on the oxide surface terminations and are correlated to the electronic structures and acid-base properties of the corresponding oxide phases, which reveal insight into the nature of the active sites and into the catalytic function of semiconducting oxides in general. Catalytic studies, using a batch reactor arrangement at high gas pressures and post reaction surface analysis, showed that only α-Fe 2 O 3 (0001) containing surface defects is catalytically active, whereas Fe 3 O 4 (111) is always inactive. This can be related to the elementary adsorption and desorption properties observed in ultrahigh vacuum, which indicates that the surface chemical properties of the iron-oxide films do not change significantly across the "pressure-gap". A model is proposed according to which the active site involves a regular acidic surface sites and a defect site next to it. The results on metal-oxide surface chemistry also have implications for other fields, such as environmental science, biophysics and chemical sensors.-2 -"2kyEi9FYSQjBVrZxIPQ.FHIAC_WRa02_review.doc", Datum: 19.02.03

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Section: Xas Measurementssupporting

confidence: 76%

Surface chemistry and catalysis on well-defined epitaxial iron-oxide layers

Weiß

Ranke

2002

Progress in Surface Science

584

610

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“…At this point, it is instructive to consider the molecular orbitals for an octahedral transition-metal oxide containing a first-row transition metal [11], although the octahedral O h symmetry around the cation is usually slightly distorted [12]. In this depiction, the metal 4s orbitals bond with the ligand orbitals to form the a 1g b level, the metal 3d x 2 ÿy 2 and 3d z 2 orbitals bond with the ligand orbitals to form the e g b level, the metal 4p orbitals bond with both the ligand and orbitals to form the t 1u b and t 1u b levels, and the metal 3d xy , 3d xz , and 3d yz orbitals bond with the ligand orbitals to form the t 2g b level.…”

Section: Volume 89 Number 7 P H Y S I C a L R E V I E W L E T T E R mentioning

confidence: 99%

Hybridization and Bond-Orbital Components in Site-Specific X-Ray Photoelectron Spectra of RutileTiO2

et al. 2002

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“…In analyzing the oxygen K-edge it is convenient to break to spectrum up into two sections. The first section, involving the first 5-10eV above the threshold, has been previously identified as resulting from hybridization between the oxygen 2p and transition-metal (Ti) 3d levels (Grunes et al, 1982). As described by de Grootet al (1993), the perovskite structure represents the prototype for a tight-binding description of the TiC6 s" cluster.…”

Section: $ ~Imdmenlalmentioning

confidence: 99%

Interpreting atomic resolution EELS spectra using multiple scattering theory

Moltaji¹,

Buban²,

Browning³

1999

J Synchrotron Radiat

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By performing electron energy loss spectroscopy (EELS) in a scanning transmission electron microscope (STEM) it is possible to obtain atomic spatial resolution spectra from individual defects. Using the multiple scattering methodology originally developed for X-ray absorption Near-Edge Structure (XANES), the fine-structure of the energy loss spectra can be directly related to the local 3-dimensional atomic structure. This type of analysis allows unique structure models to be developed for defects, on which a fundamental understanding of the structure-property relationships can be based. The application of this technique is demonstrated here for a 25 ° [001] tilt grain boundary in SrTiO3.

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OxygenKnear-edge fine structure: An electron-energy-loss investigation with comparisons to new theory for selected3dTransition-metal oxides

Cited by 337 publications

References 48 publications

Surface chemistry and catalysis on well-defined epitaxial iron-oxide layers

Surface chemistry and catalysis on well-defined epitaxial iron-oxide layers

Hybridization and Bond-Orbital Components in Site-Specific X-Ray Photoelectron Spectra of RutileTiO2

Interpreting atomic resolution EELS spectra using multiple scattering theory

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