New type of auger effect and its influence on the x-ray spectrum

“…In general, the spectral structures at the L 2 edge are broader than the ones at L 3 due to the presence of an extra desexcitation channel, the Coster-Krönig effect. 44 Hence, distinct convolution widths are needed at the two edges in order to reproduce the spectral shape. Furthermore, to account for inelastic scattering events (e.g., plasmons), a Lorentzian with a more sophisticated energy dependence is sometimes preferred to a steplike function.…”

Section: Technical Detailsmentioning

confidence: 99%

Projector augmented wave calculation of x-ray absorption spectra at theL2,3edges

Bunǎu

Calandra

2013

Phys. Rev. B

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We develop a technique based on density functional theory and the projector augmented wave method in order to obtain the x-ray absorption cross section at a general edge, both in the electric dipole and quadrupole approximations. The method is a generalization of Taillefumier et al., [Phys. Rev. B 66, 195107 (2002)]. We apply the method to the calculation of the Cu L 2,3 edges in fcc copper and cuprite (Cu 2 O), and to the S L 2,3 edges in molybdenite (2H-MoS 2 ). The role of core-hole effects, modeled in a supercell approach, as well as the decomposition of the spectrum into different angular momentum channels are studied in detail. In copper we find that the best agreement with experimental data is obtained when core-hole effects are neglected. On the contrary, core-hole effects need to be included both in Cu 2 O and 2H-MoS 2 . Finally we show that a non-negligible component of S L 2,3 edges in 2H-MoS 2 involves transition to states with s character at all energy scales. The inclusion of this angular momentum channel is mandatory to correctly describe the angular dependence of the measured spectra. We believe that transitions to s character states are quantitatively significant at the L 2,3 edges of third row elements from Al to Ar.

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“…These intensities are due to a cascade process including a radiationless Coster−Kronig (CK) transition 67 as schematically depicted in Figure 2c and 6 ] 3+ complex. In Figure 3 the corresponding features are labeled with CK.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

From Ligand Fields to Molecular Orbitals: Probing the Local Valence Electronic Structure of Ni²⁺ in Aqueous Solution with Resonant Inelastic X-ray Scattering

et al. 2013

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Bonding of the Ni 2+ (aq) complex is investigated with an unprecedented combination of resonant inelastic X-ray scattering (RIXS) measurements and ab initio calculations at the Ni L absorption edge. The spectra directly reflect the relative energies of the ligand-field and charge-transfer valence-excited states. They give element-specific access with atomic resolution to the ground-state electronic structure of the complex and allow quantification of ligand-field strength and 3d−3d electron correlation interactions in the Ni 2+ (aq) complex. The experimentally determined ligand-field strength is 10Dq = 1.1 eV. This and the Racah parameters characterizing 3d−3d Coulomb interactions B = 0.13 eV and C = 0.42 eV as readily derived from the measured energies match very well with the results from UV−vis spectroscopy. Our results demonstrate how L-edge RIXS can be used to complement existing spectroscopic tools for the investigation of bonding in 3d transition-metal coordination compounds in solution. The ab initio RASPT2 calculation is successfully used to simulate the L-edge RIXS spectra. ■ INTRODUCTION3d transition metals in aqueous solution are interesting from a fundamental point of view as their hexaaqua complexes [M(H 2 O) 6 ] n+ represent the archetype of Werner complexes with coordinative bonding in octahedral symmetry. 1 Considering hydrogen bonding between the various coordination spheres of water molecules, they could even be regarded as chelate complexes, 2 and new insight into their electronic structure could help understanding the interplay of bonding, structure, and dynamics in these complexes. This in turn forms the basis for understanding their thermodynamic properties and reactivity, having implications for modeling and understanding phenomena ranging from water exchange reactions 3,4 to photochemical processes 5 and atmospheric liquid chemistry of 3d transition-metal ions in solution. 6 While the structure of 3d transition metal (TM) ions and their complexes in aqueous solution can be addressed experimentally with numerous scattering and spectroscopic methods, 7 bonding can be assessed with a limited set of spectroscopic tools among which, historically, UV−vis spectroscopy has played a dominant role. Complementing such experimental results and due to the strongly polarized character of the coordinate bond, ligand-field theory 8,9 can be successfully applied to hexaaqua complexes. In particular, the dependence of the ligand-field (LF) state energies on ligand-field strength and 3d−3d Coulomb interactions for all 3d n complexes were first calculated by Tanabe and Sugano in their seminal work from 1954. 10,11 The low-energy electronic excited state spectrum of a typical TM coordination complex can thus be described by, with increasing photon energy, the LF excitations, followed by the charge-transfer (CT) and ligand-centered excitations. At present, the excitations to LF states of octahedral TM complexes are very well understood at the semiempirical level of ligand-field theory. Today, ab ini...

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New type of auger effect and its influence on the x-ray spectrum

Cited by 244 publications

References 1 publication

Final-state effect on x-ray photoelectron spectrum of nominallyd1andn-dopedd0transition-metal oxides

Final-state effect on x-ray photoelectron spectrum of nominallyd1andn-dopedd0transition-metal oxides

Projector augmented wave calculation of x-ray absorption spectra at theL2,3edges

From Ligand Fields to Molecular Orbitals: Probing the Local Valence Electronic Structure of Ni²⁺ in Aqueous Solution with Resonant Inelastic X-ray Scattering

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New type of auger effect and its influence on the x-ray spectrum

Cited by 244 publications

References 1 publication

Final-state effect on x-ray photoelectron spectrum of nominallyd1andn-dopedd0transition-metal oxides

Final-state effect on x-ray photoelectron spectrum of nominallyd1andn-dopedd0transition-metal oxides

Projector augmented wave calculation of x-ray absorption spectra at theL2,3edges

From Ligand Fields to Molecular Orbitals: Probing the Local Valence Electronic Structure of Ni2+ in Aqueous Solution with Resonant Inelastic X-ray Scattering

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Product

Resources

About

From Ligand Fields to Molecular Orbitals: Probing the Local Valence Electronic Structure of Ni²⁺ in Aqueous Solution with Resonant Inelastic X-ray Scattering