Core excitations of symmetrical aromatic molecules. Specific correlations in the valence shell and localization in the core shells

Schwarz, Winfried H.; Chang, Tse‐Chiang; Seeger, Ute; Hwang, Kuang Hung

doi:10.1016/0301-0104(87)80098-8

Cited by 89 publications

(36 citation statements)

References 67 publications

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“…41 While the spectra for benzene on Ni exhibit only one structure C at 293.5 eV, two peaks CЈ ͑293.4 eV͒ and C ͑294.1 eV͒ are clearly separated for the Cu surface. From the polarization dependence and energy position peak C is identified as the shape resonance ͑ symmetry͒, while peak CЈ is assigned to a shake up transition in line with multiconfiguration Hartree-Fock ͑MCHF͒ calculations, 36 which predict an admixture of shakeup transitions in this energy region. The somewhat weaker polarization dependence of peak C as compared to peak D observed for benzene on Ni͑100͒ and reported for other substrates 32 supports the given assignment.…”

Section: B Xassupporting

confidence: 56%

“…A similar intensity reduction is also seen for peaks B and CЈ, which involve shakeup transitions. 36 Overall the strong coupling will lead to a hybridization of the system with substrate states and we expect a broadening of the involved molecular transitions. As discussed in Ref.…”

Section: B Xasmentioning

confidence: 96%

“…29 Schwarz et al concluded that, due to configuration interaction, this transition has substantial amount of highest occupied molecular orbital-lowest occupied molecular orbital ͓C(1s)→e 2u , e 1g →e 2u ͔ shakeup character. 36 Recent static exchange ͑STEX͒ calculations by Pettersson et al of the benzene XA spectrum predict that the oscillator strength of the b 2g transition is too weak to account for peak B. 37,38 Accordingly peak B has to stem mainly from shakeup contributions.…”

Section: B Xasmentioning

confidence: 99%

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Electronic structure of benzene on Ni(100) and Cu(110): An x-ray-spectroscopy study

et al. 1998

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The valence electronic structure of benzene chemisorbed on Ni͑100͒ and Cu͑110͒ has been studied using angle-dependent x-ray emission and x-ray absorption spectroscopy. These techniques allow us to resolve the benzene p contributions involved in the chemical bond. Symmetry selection rules observed in resonant inelastic x-ray scattering are applied for the adsorbate case to identify the symmetry of new states formed in the chemical bond. Based on x-ray absorption results we conclude that benzene adsorbs with the molecular plane parallel to both surfaces. On Ni a new, third state is observed 1.8 eV below the Fermi level. Comparing resonant and nonresonant excitation its symmetry character is identified as being of e 2u type. The corresponding *e 2u x-ray absorption intensity is strongly reduced. This is attributed to a splitting of the previously unoccupied e 2u orbital into bonding and antibonding states due to adsorbate -substrate 3d interaction leading to a backdonation bond. Moreover, a broad distribution of -symmetric states is observed all the way up to the Fermi level, indicating that despite of rehybridization states also contribute to the chemical bond. On Cu͑110͒ in contrast a new, third state is cut by the Fermi level. This indicates a resonancelike broadening of the e 2u orbital due to interaction with the Cu sp band. Additional benzene density of states is observed that tracks emission and is attributed to weak hybridization in the chemisorbed state. The presented results give insights in the bonding of benzene to metal substrates and suggest that the usual -donation bonding model of benzene to metal surfaces has to be extended.

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Section: B Xassupporting

confidence: 56%

Section: B Xasmentioning

confidence: 96%

Section: B Xasmentioning

confidence: 99%

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Electronic structure of benzene on Ni(100) and Cu(110): An x-ray-spectroscopy study

et al. 1998

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“…p Ã (b 2 g), and 1s ? r Ã (e 2 g) transitions [36]. In contrast to the carbon X-ray absorption spectrum of benzene, the peak located at 285 eV in the pyridine spectrum is divided into a ''b1'' and ''a1'' symmetry component due to the presence of nitrogen in the aromatic ring.…”

Section: Scanning Transmission X-ray Microscopy Of Brønsted Acidity Cmentioning

confidence: 98%

Interplay between nanoscale reactivity and bulk performance of H-ZSM-5 catalysts during the methanol-to-hydrocarbons reaction

Aramburo

Teketel

Svelle

et al. 2013

Journal of Catalysis

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H-ZSM-5 catalyst powders before and after a steaming post-treatment have been investigated during the Methanol-To-Hydrocarbons (MTH) process at 350°C. Bulk and surface characterization techniques have been combined with in situ Scanning Transmission X-ray Microscopy (STXM) at the aluminum and carbon K-edge to study the changes in acidity, porosity, reactivity, and aluminum distribution upon steaming. It was found that steaming post-treatment has a positive impact on the stability of H-ZSM-5 without inducing important changes in the MTH activity and selectivity. The lower MTH stability of non-steamed H-ZSM-5 catalyst powder is related to the formation of poly-aromatic compounds in the outer regions of the catalyst particles, as probed with in situ STXM. In contrast, a limited amount of poly-aromatics was found in the outer rim of steamed H-ZSM-5 catalyst particles. These differences occur as a result of the generation of mesoporosity as well as the reduction in the number and strength of acid sites after steaming, as evidenced by the nanoscale imaging of adsorbed pyridine with STXM.

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“…During decades of application, these methods have acquired a reputation of being the “golden standard” for this type of problems . From the 1980s on, when the first efficient and rapidly converging algorithms for MCSCF have been developed, also K ‐edge core‐level spectra for diatomics and small polyatomic molecules have been calculated . During the last years, investigations of L ‐edge X‐ray spectra of TM compounds emerged, where it has been shown to be able to cope with highly excited states in multiconfigurational situations …”

Section: Theoretical Methodsmentioning

confidence: 99%

Theoretical X‐ray spectroscopy of transition metal compounds

Bokarev

Kühn

2019

WIREs Comput Mol Sci

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X-ray spectroscopy is one of the most powerful tools to access structure and properties of matter in different states of aggregation as it allows to trace atomic and molecular energy levels in course of various physical and chemical processes. Xray spectroscopic techniques probe the local electronic structure of a particular atom in its environment, in contrast to ultraviolet/visible (UV/Vis) spectroscopy, where transitions generally occur between delocalized molecular orbitals. Complementary information is provided by using a combination of different absorption, emission, scattering as well as photo-and autoionization X-ray methods. However, interpretation of the complex experimental spectra and verification of experimental hypotheses is a nontrivial task and powerful first principles theoretical approaches that allow for a systematic investigation of a broad class of systems are needed. Focusing on transition metal compounds, L-edge spectra are of particular relevance as they probe the frontier d-orbitals involved in metal-ligand bonding. Here, neardegeneracy effects in combination with spin-orbit coupling lead to a complicated multiplet energy level structure, which poses a serious challenge to quantum chemical methods. Multiconfigurational self-consistent field (MCSCF) theory has been shown to be capable of providing a rather detailed understanding of experimental X-ray spectroscopy. However, it cannot be considered as a "blackbox" tool and its application requires not only a command of formal theoretical aspects, but also a broad knowledge of already existing applications. Both aspects are covered in this overview.

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Core excitations of symmetrical aromatic molecules. Specific correlations in the valence shell and localization in the core shells

Cited by 89 publications

References 67 publications

Electronic structure of benzene on Ni(100) and Cu(110): An x-ray-spectroscopy study

Electronic structure of benzene on Ni(100) and Cu(110): An x-ray-spectroscopy study

Interplay between nanoscale reactivity and bulk performance of H-ZSM-5 catalysts during the methanol-to-hydrocarbons reaction

Theoretical X‐ray spectroscopy of transition metal compounds

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