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Bocharov, S.; Dräger, G.; Heumann, D.; Šimůneḱ, A.; Šipr, O.

doi:10.1103/physrevb.58.7668

Cited by 19 publications

(18 citation statements)

References 21 publications

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“…Titanium has a formal 3d 0 confi guration in TiS 2 , which allows for extensive hybridization of empty metal 3d orbitals with unoccupied S 3s * and 3p * antibonding orbitals. Thus, the S K-edge feature of TiS 2 is also split by the crystal fi eld into two peaks of nearly equal intensity (Wu et al 1997, Fleet et al 2005c, and is fairly well reproduced by multiple-scattering calculations (Wu et al 1997, Bocharov et al 1998. The edge features of the S L-edge XANES spectra for niningerite (MgS) and oldhamite (CaS) are strong (Farrell et al 2002), but remain diffi cult to assign in terms of simple L 3 ,L 2 doublets, even after fairly rigorous theoretical study .…”

Section: S L-edge Xanes Spectramentioning

confidence: 81%

Xanes Spectroscopy of Sulfur in Earth Materials

Fleet¹

2005

The Canadian Mineralogist

152

143

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X-ray absorption near-edge structure (XANES) spectroscopy is the ideal non-destructive technique for characterizing and quantifying S species in compositionally complex natural materials such as silicate glasses and minerals, coals, asphalts and asphaltenes, kerogens and humic substances. Sulfur absorption edges represent the transition of S 1s and 2p core electrons to unoccupied antibonding orbitals at the bottom of the conduction band. Shifts in the position of the absorption-edge feature of S K-and L-edge XANES spectra constitute a chemical ruler for oxidation state of both inorganic and organic species of S; the S K edge shifts from 2469.5 eV for chalcopyrite (2-oxidation state) to 2482 eV for gypsum (6+). However, chemical state of S in Earth materials is most readily assigned by comparing the overall XANES profi le with spectra for reference compounds. Sulfur XANES spectra are reviewed for pyrite, troilite, pyrrhotite and NiAs-type Co 0.923 S and Ni 0.923 S, niningerite (MgS), oldhamite (CaS), alabandite (MnS) and cubic FeS, and sphalerite and related phases, as well as for selected solid-solutions of the monosulfi des. Sulfur XANES spectra for FeS, CoS, NiS, MgS, CaS, MnS and ZnS have been simulated by multiple scattering calculations. The S K-edge XANES of transition-metal-bearing monosulfi des generally show anomalous absorption consistent with hybridization of the fi nal S 3p * antibonding states with empty 3d orbitals on the metal atoms. Various applications of S K-and L-edge XANES fi ngerprinting are discussed, including speciation of inorganic S in basaltic glasses, lazurite and haüyne, identifi cation of organic functional groups of S in coals, kerogens and humic substances extracted from subtropical soils and marine sediments, and the association of sulfated sugars with calcifi cation of coral aragonite skeletons.Keywords: XANES spectroscopy, chemical state of S, electronic structure and bonding, sulfi des, sulfates, magma, organic geochemistry. SOMMAIRELa spectroscopie d'absorption des rayons X dans la région pré-seuil (XANES) s'avère la technique non-destructive par excellence pour caractériser et quantifi er les espèces de soufre dans les matériaux naturels de composition complexe, par exemple les verres silicatés et minéraux, charbons, asphaltes et asphaltènes, kérogènes et substances humiques. Les seuils d'absorption du soufre résultent de la transition des électrons 1s et 2p du noyau à des orbites non occupés anti-liaisons à la base de la bande de conduction. Les décalages dans la position des seuils K et L du soufre des spectres XANES constituent un barème chimique important dans l'évaluation du niveau d'oxydation du soufre, à la fois pour les espèces inorganiques et organiques; le seuil K est déplacé de 2469.5 eV dans la chalcopyrite (valence 2-) à 2482 eV dans le gypse (6+). Toutefois, l'état du soufre des matériaux terrestres est plus facilement attribué en comparant le profi l XANES entier d'un échantillon aux spectres des composés de réfé-rence. Les spectres XANES du soufre so...

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Section: S L-edge Xanes Spectramentioning

confidence: 81%

Xanes Spectroscopy of Sulfur in Earth Materials

Fleet¹

2005

The Canadian Mineralogist

152

143

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“…The maximum absorption anisotropy for TiS 3 occurs in the (0 0 1) plane of the layer unit, rather than normal to the layer unit as in the MX 2 chalcogenides [17,18,21], wurtzite-type nitrides [20], and V 2 O 5 [19]. This difference in the orientation of the anisotropy is probably related to the presence of two strongly-bonded and mutually perpendicular features in the layer unit of the trisulfide: the TiS 6 chain (the quasi-one-dimensional structural unit) parallel to the b-axis and the disulfide group parallel to the a-axis (Fig.…”

Section: Polarization Effectsmentioning

confidence: 98%

“…X-ray absorption spectroscopy is also sensitive to anisotropy of crystal structure because the absorption edge features are dependent on both the initial and final electron states, thus permitting the anisotropy of conduction states to be probed. Layer-structure compounds, like the transitionmetal chalcogenides, hexagonal nitrides, and V 2 O 5 , have been particularly well studied in this respect [17][18][19][20][21]. The last of these studies investigated the polarized X-ray absorption of the hexagonal CdI 2 -structure chalcogenides TiS 2 , TiSe 2 and TiTe 2 , which have uniaxial physical (optical, electric, magnetic) properties and maximum anisotropy parallel to the c-axis.…”

Section: Introductionmentioning

confidence: 98%

Polarized X-ray absorption spectroscopy and XPS of TiS3: S K- and Ti L-edge XANES and S and Ti 2p XPS

et al. 2005

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“…Both Ti K-edge and Te L 1 -edge XANES spectra display distinct polarization dependence [19,22]. Similarly to in the case of ZnS, the convergence of the calculated spectra with respect to the size of the cluster is different for the Ti and the Te edges: it was found that at least 51 atoms are needed to get a converged Ti-edge spectrum (a cluster of 25 atoms is insufficient), while 105 atoms are needed to get a converged Te-edge spectrum (57 atoms are far too few) [19].…”

Section: Xanes Spectra Of Titementioning

confidence: 99%

Untitled

Braginsky¹,

Герштейн²,

Okun³

et al. 2007

PHYS-USP

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The site dependence and degree of localization of the total density of unoccupied states around various atoms inside a finite cluster are investigated, with the aim of exploring the potential of this kind of analysis for understanding some trends in calculated x-ray absorption near-edge-structure (XANES) spectra. The local density of states (DOS) around atoms at the surface of a cluster is in principle quite similar to the DOS around atoms in its interior; the only difference is that the heights of the peaks in the DOS are much smaller around the surface atoms than around the bulk ones. The proximity of a surface has a lesser effect on the DOS around subsurface atoms than the presence of a large number of other atoms in the bulk region of a large cluster. The fine structure in the excess density of states, evaluated via the Lloyd formula, is almost exclusively generated inside the cluster under study. Analysing the local DOS increases our understanding of distinct peculiarities in the cluster-size effect in XANES spectra in some cases.

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Polarized x-ray-absorption spectra ofTiS2,TiSe2,<

Cited by 19 publications

References 21 publications

Xanes Spectroscopy of Sulfur in Earth Materials

Xanes Spectroscopy of Sulfur in Earth Materials

Polarized X-ray absorption spectroscopy and XPS of TiS3: S K- and Ti L-edge XANES and S and Ti 2p XPS

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