Full Multiple Scattering and Crystal Field Multiplet Calculations Performed on the Spin Transition FeII(phen)2(NCS)2 Complex at the Iron K and L2,3 X-ray Absorption Edges

1995 ◽  
Vol 117 (3) ◽  
pp. 1019-1026 ◽  
Author(s):  
V. Briois ◽  
Ch. Cartier dit Moulin ◽  
Ph. Sainctavit ◽  
Ch. Brouder ◽  
A.-M. Flank
Keyword(s):  
Multiple Scattering ◽  
Crystal Field ◽  
Spin Transition ◽  
X Ray ◽  
X Ray Absorption ◽  
Absorption Edges

scholarly journals Al-driven peculiarities of local coordination and magnetic properties in single-phase Alx-CrFeCoNi high-entropy alloys

Nano Research ◽  
2021 ◽  
Author(s):  
Alevtina Smekhova ◽  
Alexei Kuzmin ◽  
Konrad Siemensmeyer ◽  
Chen Luo ◽  
Kai Chen ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Single Phase ◽  
Magnetic Circular Dichroism ◽  
Surface Region ◽  
Face Centered Cubic ◽  
X Rays ◽  
X Ray ◽  
High Entropy ◽  
X Ray Absorption ◽  
Absorption Edges

AbstractModern design of superior multi-functional alloys composed of several principal components requires in-depth studies of their local structure for developing desired macroscopic properties. Herein, peculiarities of atomic arrangements on the local scale and electronic states of constituent elements in the single-phase face-centered cubic (fcc)- and body-centered cubic (bcc)-structured high-entropy Alx-CrFeCoNi alloys (x = 0.3 and 3, respectively) are explored by element-specific X-ray absorption spectroscopy in hard and soft X-ray energy ranges. Simulations based on the reverse Monte Carlo approach allow to perform a simultaneous fit of extended X-ray absorption fine structure spectra recorded at K absorption edges of each 3d constituent and to reconstruct the local environment within the first coordination shells of absorbers with high precision. The revealed unimodal and bimodal distributions of all five elements are in agreement with structure-dependent magnetic properties of studied alloys probed by magnetometry. A degree of surface atoms oxidation uncovered by soft X-rays suggests different kinetics of oxide formation for each type of constituents and has to be taken into account. X-ray magnetic circular dichroism technique employed at L2.3 absorption edges of transition metals demonstrates reduced magnetic moments of 3d metal constituents in the sub-surface region of in situ cleaned fcc-structured Al0.3-CrFeCoNi compared to their bulk values. Extended to nanostructured versions of multicomponent alloys, such studies would bring new insights related to effects of high entropy mixing on low dimensions.

X-RAY ABSORPTION EDGES OF TRANSITION- METAL-DOPED Y1Ba2Cu3−xMxO7−∂

1988 ◽  
Vol 02 (05) ◽  
pp. 1153-1156 ◽  
Author(s):  
J. B. BOYCE ◽  
F. BRIDGES ◽  
T. CLAESON ◽  
T. H. GEBALLE ◽  
M. NYGREN ◽  
...  
Keyword(s):  
Transition Metal ◽  
X Ray ◽  
Metal Doped ◽  
X Ray Absorption ◽  
Absorption Edges

Extended X-ray absorption fine structure and multiple-scattering simulation of nickel dithiolene complexes Ni[S2C2(CF3)2]2n(n= −2, −1, 0) and an olefin adduct Ni[S2C2(CF3)2]2(1-hexene)

2015 ◽  
Vol 22 (1) ◽  
pp. 124-129 ◽  
Author(s):  
Weiwei Gu ◽  
Hongxin Wang ◽  
Kun Wang
Keyword(s):  
Fine Structure ◽  
Multiple Scattering ◽  
Edge Structure ◽  
X Ray ◽  
Absorption Fine ◽  
Square Planar ◽  
Square Planar Complexes ◽  
Uv Visible ◽  
Edge Features ◽  
X Ray Absorption

A series of Ni dithiolene complexes Ni[S2C2(CF3)]2n(n= −2, −1, 0) (1,2,3) and a 1-hexene adduct Ni[S2C2(CF3)2]2(C6H12) (4) have been examined by NiK-edge X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine-structure (EXAFS) spectroscopies. Ni XANES for1–3reveals clear pre-edge features and approximately +0.7 eV shift in the NiK-edge position for `one-electron' oxidation. EXAFS simulation shows that the Ni—S bond distances for1,2and3(2.11–2.16 Å) are within the typical values for square planar complexes and decrease by ∼0.022 Å for each `one-electron' oxidation. The changes in NiK-edge energy positions and Ni—S distances are consistent with the `non-innocent' character of the dithiolene ligand. The Ni—C interactions at ∼3.0 Å are analyzed and the multiple-scattering parameters are also determined, leading to a better simulation for the overall EXAFS spectra. The 1-hexene adduct4presents no pre-edge feature, and its NiK-edge position shifts by −0.8 eV in comparison with its starting dithiolene complex3. Consistently, EXAFS also showed that the Ni—S distances in4elongate by ∼0.046 Å in comparison with3. The evidence confirms that the neutral complex is `reduced' upon addition of olefin, presumably by olefin donating the π-electron density to the LUMO of3as suggested by UV/visible spectroscopy in the literature.

scholarly journals Anisotropy of X-ray Absorption Cross Section in CeCoGe3 Single Crystal

Crystals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 544
Author(s):  
Andrei Rogalev ◽  
Fabrice Wilhelm ◽  
Elena Ovchinnikova ◽  
Aydar Enikeev ◽  
Roman Bakonin ◽  
...  
Keyword(s):  
Cross Section ◽  
Absorption Cross Section ◽  
Linear Dichroism ◽  
X Rays ◽  
Absorption Cross ◽  
X Ray ◽  
Measured Absorption ◽  
Linearly Polarized ◽  
X Ray Absorption ◽  
Absorption Edges

Absorption spectra of two orthogonal linearly polarized x-rays in a single CeCoGe3 crystal were measured at the ID12 beamline of the ESRF for the energies near the K-edges of Ge, Co and near the L23 edges of Ce. The X-ray natural linear dichroism (XNLD) was revealed in the vicinity of all the absorption edges, which indicates a splitting of electronic states in a crystalline field. Mathematical modelling in comparison with experimental data allowed the isotropic and anisotropic parts of atomic absorption cross section in CeCoGe3 to be determined near all measured absorption edges. The calculations also show that the “average” anisotropy of the cross section close to the Ge K-edge revealed in the experiment is less than the partial anisotropic contributions corresponding to Ge atoms in two different Wyckoff positions.

scholarly journals Crystal-Field Mediated Electronic Transitions of EuS up to 35 GPa

2021 ◽  
Author(s):  
Virginia Monteseguro ◽  
Jose Antonio Barreda-Argüeso ◽  
Javier Ruiz-Fuertes ◽  
Angelika Rosa ◽  
Holger L. Meyerheim ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Crystal Field ◽  
Local Structure ◽  
Electronic Transitions ◽  
Metallic State ◽  
X Ray ◽  
Half Metal ◽  
Consistent Model ◽  
X Ray Absorption ◽  
Pressure Evolution

Abstract An advanced experimental and theoretical model to explain the correlation between the electronic and local structure of Eu2+ in two different environments within a same compound, EuS, is presented. EuX monochalcogenides (X: O, S, Se, Te) exhibit anomalies in all their properties around 14 GPa with a semiconductor to metal transition. Although it is known that these changes are related to the 4f75d0 → 4f65d1 electronic transition, no consistent model of the pressure-induced modifications of the electronic structure currently exists. We show, by optical and x-ray absorption spectroscopy, and by ab initio calculations up to 35 GPa, that the pressure evolution of the crystal field plays a major role in triggering the observed electronic transitions from semiconductor to the half-metal and finally to the metallic state.

Adsorption site, growth, and structure of Co on Cu(111) determined by multiple-scattering analysis of x-ray-absorption spectra

1995 ◽  
Vol 52 (15) ◽  
pp. 11462-11466 ◽  
Author(s):  
P. Le Fevre ◽  
H. Magnan ◽  
O. Heckmann ◽  
V. Briois ◽  
D. Chandesris
Keyword(s):  
Multiple Scattering ◽  
Absorption Spectra ◽  
Adsorption Site ◽  
X Ray ◽  
X Ray Absorption

X-ray magnetic circular dichroism study of SmAl2 using the M4,5 x-ray absorption edges

2003 ◽  
Vol 93 (10) ◽  
pp. 8337-8339 ◽  
Author(s):  
S. S. Dhesi ◽  
P. Bencok ◽  
N. B. Brookes ◽  
G. van der Laan ◽  
R. M. Galéra
Keyword(s):  
Circular Dichroism ◽  
Magnetic Circular Dichroism ◽  
X Ray ◽  
X Ray Absorption ◽  
Circular Dichroïsm ◽  
Absorption Edges
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