Resonant Inelastic X-ray Scattering (RIXS)
 is an X-ray in, X-ray out technique that enables one to study the 
dispersion of excitations in solids. In this thesis, we investigated how
 various elementary excitations of transition metal oxides show up in 
RIXS spectra.

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Resonant Inelastic X-ray Scattering Studies of Elementary Excitations

High resolution 1s core hole X-ray spectroscopy in 3d transition metal complexes—electronic and structural information

Size effects in the Raman spectra of TiO2 nanoparticles

The characteristics of pre-edge peaks in K-edge x-ray absorption near edge structure (XANES) spectra of 3d transition metals were reviewed from viewpoints of the selection rule, coordination number, number of d-electrons, and symmetry of the coordination sphere. The contribution of the electric dipole and quadrupole transition to the peaks was discussed on the basis of the group theory, polarized spectra, and theoretical calculations. The pre-edge peak intensity for Td symmetry is larger than those for Oh symmetry for all 3d elements. The intense pre-edge peak for tetrahedral species of 3d transition metals is not due to 1s–3d transition, but transition to the p component in d–p hybridized orbital. The mixing of metal 4p orbitals with the 3d orbitals depends strongly on the coordination symmetry, and the possibility is predictable by group theory. The transition of 1s electron to d orbitals is electric quadrupole component in any of the symmetries. The d–p hybridization does not occur with regular octahedral symmetry, and the weak pre-edge peak consists of 1s–3d electric quadrupole transition. The pre-edge peak intensity for a compound with a tetrahedral center changes as a function of the number of 3d electrons regardless of the kind of element; it is maximized at d0 and gradually decreases to zero at d10. The features of pre-edge peaks in K-edge XANES spectra for 4d elements and the L1-edge for 5d elements are analogous with those for 3d elements, but the pre-edge peak is broadened due to the wide natural width of the core level. Copyright © 2008 John Wiley & Sons, Ltd.

Assignment of pre‐edge peaks in K‐edge x‐ray absorption spectra of 3d transition metal compounds: electric dipole or quadrupole?

X-ray absorption and dichroism of transition metals and their compounds

The available calculated density of states of TiO2 does not predict the very first weak peak at the onset of the Ti K-edge absorption spectra indicating that this feature is not simply due to a one-electron (dipole) transition. In this short paper we present a joint experimental and theoretical study of all the three weak pre-peaks at the Ti K-edge of TiO2. Our interpretation takes into account both dipole and quadrupole transitions as well as the influence of the core hole effect.

https://iopscience.iop.org/article/10.1209/0295-5075/18/1/016/pdf

Experimental and Theoretical Investigation of the Pre-Peaks at the Ti K-Edge Absorption Spectra in TiO2

Theory of many-body effects in valence, core-level and isochromat spectroscopies along the 3d transition metal series of oxides

We rationalize the origins of a threshold instability and the mechanism of finite temperature fragmentation in highly Si-doped ${\mathrm{C}}_{60\ensuremath{-}m}{\mathrm{Si}}_{m}$ heterofullerenes via a first-principles approach. Cage disruption is driven by enhanced fluctuations of the most internal Si atoms. These are located within fully segregated Si regions neighboring the C-populated part of the cage. The predominance of inner Si atoms over those involved in Si-C bonds marks the transition from thermally stable to unstable ${\mathrm{C}}_{60\ensuremath{-}m}{\mathrm{Si}}_{m}$ systems at $m=20$.

Dynamical identification of a threshold instability in Si-doped heterofullerenes.

We analyze Ni 2 p →3 d →2 p resonant X-ray emission spectroscopy (RXES) of NiO with the impurity Anderson model. We pay attention to the inelastic X-ray scattering structures arising from the interatomic charge transfer (CT) from ligand state to 3 d state. We take into account a finite width of the O 2 p valence band in order to reproduce the experimental CT excitations in RXES, where two different CT structures are observed depending on the incident photon energy set in the CT satellite region of X-ray absorption spectra. The origin of these two CT excitation peaks is ascribed to the lower and upper edges of the 3 d 9 L nonbonding band in the final state of RXES. The value of CT energy Δ is estimated from our calculation. By analyzing XAS and RXES simultaneously with changing Δ from 2.0 eV to 6.5 eV by the step of 0.5 eV, we conclude that the most appropriate value of Δ is 3.5 eV. Also, in our calculation two different geometrical configurations are considered, which are called polarized and depolarized ...

Charge Transfer Excitation in Resonant X-ray Emission Spectroscopy of NiO

2014 Using an extra-orbital model within a generalized « spd » tight-binding approximation, we calculate the chemical binding energy of a pair of hydrogen atoms in palladium within the infinite dilution limit; we find that clusters of hydrogen cannot form in accordance with inelastic neutron scattering data in 03B1-palladium hydride. The strong repulsive interaction between a pair of hydrogen impurities at distance a, where a is the host lattice parameter, seems to be related to the presence of an intermediate metallic site between the two impurities. Also we determine the chemical binding energies between a hydrogen atom and d substitutional impurities and we discuss our results in relation with recent Mössbauer experiments. Finally we calculate the chemical binding energy between two d impurities in palladium which we compare with experimental data on the enthalpy of formation. J. Physique 41 (1980) 1001-1007 SEPTEMBRE 1980, 1 Classification Pltysics Abstracts 71.55

J. C. Parlebas

Papers

Experimental and Theoretical Investigation of the Pre-Peaks at the Ti K-Edge Absorption Spectra in TiO2

Theory of many-body effects in valence, core-level and isochromat spectroscopies along the 3d transition metal series of oxides

Dynamical identification of a threshold instability in Si-doped heterofullerenes.

Charge Transfer Excitation in Resonant X-ray Emission Spectroscopy of NiO

Chemical binding energies of point defects in palladium doped with hydrogen and d impurities