Analysis of experimental extended x-ray-absorption fine-structure (EXAFS) data using calculated curved-wave, multiple-scattering EXAFS spectra

1990 ◽  
Vol 42 (17) ◽  
pp. 10843-10851 ◽  
Author(s):  
Jose Mustre ◽  
Yizhak Yacoby ◽  
Edward A. Stern ◽  
John J. Rehr
Keyword(s):  
Fine Structure ◽  
Multiple Scattering ◽  
Exafs Data ◽  
X Ray ◽  
Absorption Fine ◽  
X Ray Absorption ◽  
Exafs Spectra

scholarly journals A combined fit of total scattering and extended X-ray absorption fine structure data for local-structure determination in crystalline materials

2009 ◽  
Vol 42 (5) ◽  
pp. 867-877 ◽  
Author(s):  
V. Krayzman ◽  
I. Levin ◽  
J. C. Woicik ◽  
Th. Proffen ◽  
T. A. Vanderah ◽  
...  
Keyword(s):  
Fine Structure ◽  
Multiple Scattering ◽  
Structure Determination ◽  
Local Structure ◽  
Group Symmetry ◽  
Total Scattering ◽  
Exafs Data ◽  
X Ray ◽  
Absorption Fine ◽  
X Ray Absorption

Reverse Monte Carlo (RMC) refinements of local structure using a simultaneous fit of X-ray/neutron total scattering and extended X-ray absorption fine structure (EXAFS) data were developed to incorporate an explicit treatment of both single- and multiple-scattering contributions to EXAFS. The refinement algorithm, implemented as an extension to the public domain computer softwareRMCProfile, enables accurate modeling of EXAFS over distances encompassing several coordination shells around the absorbing species. The approach was first tested on Ni, which exhibits extensive multiple scattering in EXAFS, and then applied to perovskite-like SrAl1/2Nb1/2O3. This compound crystallizes with a cubic double-perovskite structure but presents a challenge for local-structure determination using a total pair-distribution function (PDF) alone because of overlapping peaks of the constituent partial PDFs (e.g.Al—O and Nb—O or Sr—O and O—O). The results obtained here suggest that the combined use of the total scattering and EXAFS data provides sufficient constraints for RMC refinements to recover fine details of local structure in complex perovskites. Among other results, it was found that the probability density distribution for Sr in SrAl1/2Nb1/2O3adoptsTdpoint-group symmetry for the Sr sites, determined by the ordered arrangement of Al and Nb, as opposed to a spherical distribution commonly assumed in traditional Rietveld refinements.

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.

Multiple-Scattering of Near-Edge x-ray Absorption Fine Structure of Sulphur-Passivated InP(100) Surface

2003 ◽  
Vol 20 (7) ◽  
pp. 1151-1154 ◽  
Author(s):  
Cao Song ◽  
Tang Jing-Chang ◽  
Shen Shao-Lai ◽  
Chen Geng-Sheng ◽  
Ma Dan
Keyword(s):  
Fine Structure ◽  
Multiple Scattering ◽  
X Ray ◽  
Absorption Fine ◽  
X Ray Absorption

Determination of the Structures of Antiinflammatory Copper(II) Dimers of Indomethacin by Multiple-Scattering Analyses of X-ray Absorption Fine Structure Data

2001 ◽  
Vol 40 (6) ◽  
pp. 1295-1302 ◽  
Author(s):  
Jane E. Weder ◽  
Trevor W. Hambley ◽  
Brendan J. Kennedy ◽  
Peter A. Lay ◽  
Garry J. Foran ◽  
...  
Keyword(s):  
Fine Structure ◽  
Multiple Scattering ◽  
Structure Data ◽  
X Ray ◽  
Absorption Fine ◽  
X Ray Absorption

Model Extended X-ray Absorption Fine Structure (EXAFS) Spectra from Molecular Dynamics Data for Ca2+and Al3+Aqueous Solutions

2000 ◽  
Vol 104 (45) ◽  
pp. 10467-10472 ◽  
Author(s):  
Daniel Spångberg ◽  
Kersti Hermansson ◽  
Patric Lindqvist-Reis ◽  
Farideh Jalilehvand ◽  
Magnus Sandström ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Fine Structure ◽  
Aqueous Solutions ◽  
X Ray ◽  
Absorption Fine ◽  
X Ray Absorption ◽  
Exafs Spectra
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