TheMXANprocedure: a new method for analysing the XANES spectra of metalloproteins to obtain structural quantitative information

2002 ◽  
Vol 10 (1) ◽  
pp. 51-57 ◽  
Author(s):  
M. Benfatto ◽  
S. Della Longa ◽  
C. R. Natoli
Keyword(s):  
Local Structure ◽  
Experimental Spectrum ◽  
Quantitative Information ◽  
Geometrical Parameters ◽  
Absorption Data ◽  
Edge Structure ◽  
X Ray ◽  
Fitting Procedure ◽  
Starting Conditions ◽  
X Ray Absorption

The first quantitative analyses are reported of the FeK-edge polarized X-ray absorption near-edge structure (XANES) of a single crystal of the iron protein carbonmonoxy-myoglobin (MbCO) and of its cryogenic photoproduct Mb*CO. The CO—Fe–heme local structure has been determined using a novel fitting procedure, namedMXAN, which is able to fit the XANES part (from the edge to about 200 eV) of experimental X-ray absorption data. This method is based on the comparison between the experimental spectrum and several theoretical spectra that are generated by changing the relevant geometrical parameters of the site around the absorbing atom. The theoretical spectra are derived in the framework of the full multiple-scattering approach. TheMXANprocedure is able to recover information about the symmetry and atomic distances, and the solution is found to be independent of the starting conditions. The extracted local structure of Mb*CO includes an Fe—CO distance of 3.08 (7) Å, with a tilting angle between the heme normal and the Fe—C vector of 37 (7)° and a bending angle between the Fe—C vector and the C—O bond of 31 (5)°

scholarly journals Solving local structure around dopants in metal nanoparticles with ab initio modeling of X-ray absorption near edge structure

2016 ◽  
Vol 18 (29) ◽  
pp. 19621-19630 ◽  
Author(s):  
Janis Timoshenko ◽  
Atal Shivhare ◽  
Robert W. J. Scott ◽  
Deyu Lu ◽  
Anatoly I. Frenkel
Keyword(s):  
Ab Initio ◽  
Metal Nanoparticles ◽  
Local Structure ◽  
Heterogeneous Catalysts ◽  
Edge Structure ◽  
X Ray ◽  
Metal Impurities ◽  
Local Environments ◽  
X Ray Absorption ◽  
Xanes Analysis

XANES analysis guided by ab initio modeling is proposed for refinement of local environments around metal impurities in heterogeneous catalysts.

scholarly journals Neural network assisted analysis of bimetallic nanocatalysts using X-ray absorption near edge structure spectroscopy

2020 ◽  
Vol 22 (34) ◽  
pp. 18902-18910 ◽  
Author(s):  
Nicholas Marcella ◽  
Yang Liu ◽  
Janis Timoshenko ◽  
Erjia Guan ◽  
Mathilde Luneau ◽  
...  
Keyword(s):  
Neural Network ◽  
Local Structure ◽  
Bimetallic Nanoparticles ◽  
Edge Structure ◽  
X Ray ◽  
Coordination Numbers ◽  
Rich Information ◽  
Bimetallic Nanocatalysts ◽  
Assisted Analysis ◽  
X Ray Absorption

Trained neural networks are used to extract the first partial coordination numbers from XANES spectra. In bimetallic nanoparticles, the four local structure descriptors provide rich information on structural motifs.

Local structure around In atoms in coherently grownm-plane InGaN film

2017 ◽  
Vol 24 (5) ◽  
pp. 1012-1016
Author(s):  
Takafumi Miyanaga ◽  
Takashi Azuhata ◽  
Kiyofumi Nitta ◽  
Shigefusa F. Chichibu
Keyword(s):  
Quantum Wells ◽  
Local Structure ◽  
Interatomic Distance ◽  
Compressive Strain ◽  
Local Strain ◽  
Interatomic Distances ◽  
X Ray ◽  
Fitting Procedure ◽  
Excitonic Emission ◽  
X Ray Absorption

The local structure around In atoms in anm-plane In0.06Ga0.94N film coherently grown on a freestandingm-plane GaN substrate was investigated by polarization-dependent X-ray absorption fine-structure. A step-by-step fitting procedure was proposed for them-plane wurtzite structure. The interatomic distance for the first nearest neighbour In—N atomic pairs was almost isotropic. For the second nearest In—Ga pairs, the interatomic distances along them- anda-axes were longer and shorter, respectively, than that in strain-free virtual crystals as expected for them-plane compressive strain. In contrast, the In—Ga interatomic distance in thec-direction was elongated in spite of the compressive strain, which was explained in terms of the anisotropic atomic structure on them-plane. The local strain in them-plane film was more relaxed than that in coherently grownc-plane single quantum wells. A few In atoms were atomically localized in all directions, and thus localized excitonic emission is expected as in the case ofc-plane InGaN.

Local Structure of Pr, Nd, and Sm Complex Oxides and Their X-ray Absorption Near Edge Structure Spectra

2014 ◽  
Vol 118 (36) ◽  
pp. 20881-20888 ◽  
Author(s):  
Hiroyuki Asakura ◽  
Tetsuya Shishido ◽  
Shingo Fuchi ◽  
Kentaro Teramura ◽  
Tsunehiro Tanaka
Keyword(s):  
Local Structure ◽  
Complex Oxides ◽  
Edge Structure ◽  
X Ray ◽  
X Ray Absorption
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