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.

New developments in the theory and interpretation of X-ray spectra based on fast parallel calculations

2002 ◽  
Vol 10 (1) ◽  
pp. 43-45 ◽  
Author(s):  
J. J. Rehr ◽  
A. L. Ankudinov
Keyword(s):  
Ab Initio ◽  
Structural Biology ◽  
Significant Progress ◽  
Edge Structure ◽  
New Developments ◽  
X Ray ◽  
The Past ◽  
Current State ◽  
X Ray Absorption ◽  
Made In

There has been dramatic progress over the past decade both in theory and inab initiocalculations of X-ray absorption fine structure. Significant progress has also been made in understanding X-ray absorption near-edge structure (XANES). This contribution briefly reviews the developments in this field leading up to the current state. One of the key advances has been the development of severalab initiocodes such asFEFF, which permit an interpretation of the spectra in terms of geometrical and electronic properties of a material. Despite this progress, XANES calculations have remained challenging both to compute and to interpret. However, recent advances based on parallel Lanczos multiple-scattering algorithms have led to speed increases of typically two orders of magnitude, making fast calculations practicable. Improvements in the interpretation of near-edge structure have also been made. It is suggested that these developments can be advantageous in structural biology,e.g.in post-genomics studies of metalloproteins.

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

Ab Initio XAFS and XANES Standards

1993 ◽  
Vol 307 ◽  
Author(s):  
J. J. Rehr ◽  
S. I. Zabinsky ◽  
R. C. Albers
Keyword(s):  
Fine Structure ◽  
Ab Initio ◽  
Multiple Scattering ◽  
State Of The Art ◽  
Experimental Measurements ◽  
Edge Structure ◽  
X Ray ◽  
Coordination Numbers ◽  
X Ray Absorption ◽  
Better Than

ABSTRACTAb initio x-ray-absorption fine structure (XAFS) and x-ray-absorption near edge structure (XANES) standards are developed for molecules and solids. These standard XAFS spectra are obtained from ab initio XAFS calculations, using an automated code, FEFF, which we have extended to include multiple-scattering (MS) and XANES calculations. Our treatment is based on state-of-the-art curved-wave MS theory. Sample results are presented and compared with experiment. We find that these theoretical standards are comparable with experimental measurements, yielding distance determinations better than 0.02 Å and coordination numbers better than 20%. Our approach also gives a new MS interpretation of the σ* shape-resonances in XANES.

Structure and Electronic Properties of Molecularly-capped Metal Nanoparticles: The effect of Nano-size, Metal Core and Capping Molecule Probed by X-ray Absorption Spectroscopy

2002 ◽  
Vol 738 ◽  
Author(s):  
Peng Zhang ◽  
Tsun-Kong Sham
Keyword(s):  
Fine Structure ◽  
Metal Nanoparticles ◽  
Charge Distribution ◽  
Local Structure ◽  
Structure And Properties ◽  
Metal Core ◽  
Au Nps ◽  
X Ray ◽  
X Ray Absorption ◽  
Nano Size

ABSTRACTWe have conducted an investigation using TEM, XRD and synchrotron based X-ray absorption fine structure (XAFS) to probe the structural and electronic characteristics of several molecularly capped metal nanoparticles (NPs). Three series of NPs were employed in the XAFS study to address the effect of nano-size, metal-core and capping molecules on the structure and properties of the NPs. They are (1) thiol-capped Au NPs from 1.6nm to 4.0nm, (2) thiol-capped Au and Pd NPs of ∼2nm and (3) Au NPs of ∼4nm capped by thiol and tetraoctylammonium bromide (TOAB). The results on their local structure, bonding and d-charge distribution are presented.

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