scholarly journals Background subtraction for fluorescence EXAFS data of a very dilute dopantZinZ + 1 host

2011 ◽  
Vol 18 (4) ◽  
pp. 679-680 ◽  
Author(s):  
Scott Medling ◽  
Frank Bridges
Keyword(s):  
Background Subtraction ◽  
Raman Peak ◽  
Exafs Data ◽  
X Ray ◽  
Fluorescence Peak ◽  
Large Background

When conducting EXAFS at the CuK-edge for ZnS:Cu with very low Cu concentration (<0.04% Cu), a large background was present that increased with energy. This background arises from a Zn X-ray Raman peak, which moves through the Cu fluorescence window, plus the tail of the Zn fluorescence peak. This large background distorts the EXAFS and must be removed separately before reducing the data. A simple means to remove this background is described.

Synthesis and characterisation of transition metal substituted barium hollandite ceramics

2006 ◽  
Vol 932 ◽  
Author(s):  
Neil C. Hyatt ◽  
Martin C. Stennett ◽  
Steven G. Fiddy ◽  
Jayne S. Wellings ◽  
Sian S. Dutton ◽  
...  
Keyword(s):  
Transition Metal ◽  
Oxidation State ◽  
Powder Diffraction ◽  
Single Phase ◽  
Maximum Density ◽  
Processing Conditions ◽  
Metal Oxidation ◽  
Exafs Data ◽  
X Ray ◽  
Oxygen Atoms

ABSTRACTA range of transition metal bearing hollandite phases, formulated Ba1.2B1.2Ti6.8O16 (B2+ = Mg, Co, Ni, Zn, Mn) and Ba1.2B2.4Ti5.6O16 (B3+ = Al, Cr, Fe) were prepared using an alkoxide - nitrate route. X-ray powder diffraction demonstrated the synthesis of single phase materials for all compositions except B = Mn. The processing conditions required to produce > 95 % dense ceramics were determined for all compositions, except B = Mg for which the maximum density obtained was > 93 %. Analysis of transition metal K-edge XANES data confirmed the presence of the targeted transition metal oxidation state for all compositions except B = Mn, where the overall oxidation state was found to be Mn3+. The K-edge EXAFS data of Ba1.2B1.2Ti6.8O16 (B = Ni and Co) were successfully analysed using a crystallographic model of the hollandite structure, with six oxygen atoms present in the first co-ordination shell at a distance of ca. 2.02Å. Analysis of Fe K-edge EXAFS data of Ba1.2B2.4Ti5.4O16 revealed a reduced co-ordination shell of five oxygens at ca. 1.99Å.

SEDEM, a Software Package for EXAFS Data Extraction and Modelling

1998 ◽  
Vol 5 (5) ◽  
pp. 1287-1297 ◽  
Author(s):  
Daniel Aberdam
Keyword(s):  
Software Package ◽  
Data Extraction ◽  
Direct Determination ◽  
Energy Shift ◽  
Waller Factor ◽  
Gradient Algorithm ◽  
Least Mean Square ◽  
Exafs Data ◽  
X Ray ◽  
Fourier Filtering

A software package for extended X-ray absorption fine structure (EXAFS) data extraction and modelling, running on DOS- or Windows-operated PCs, is described. This package is written with the aim of giving the user a tool to undertake all steps of data processing and modelling, rather than making use of the most recent programming facilities. However, it remains easy to use, and self-explanatory to those who have already worked with EXAFS. It is divided into two main executable pieces of software. The first one is used to extract the EXAFS k n χ(k) function from the data and isolate the shell contributions by Fourier filtering. A tool to sum the spectra before EXAFS extraction is provided. The second one is designed to model the EXAFS spectra or the shell contributions, using amplitude and phase data either from McKale's tables, computed from the FEFF program or extracted from experimental reference spectra. This modelling program allows either an optimization of the simulation by a least-mean-square gradient algorithm, with a statistical evaluation of the result of optimization, or, in the case of a single shell, a direct determination of the four main parameters (neighbour distance and number, energy shift and Debye–Waller factor) by decorrelation of the phase and amplitude. In the presence of anharmonicity, the cumulant expansion of the radial distribution of distances is obtained from the phase and amplitude decorrelation. This package is in use at the Collaborative Research Group on Interfaces (CRG-IF) bending-magnet #32 X-ray line (BM-32) at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France.

scholarly journals Operando SAXS Study of a Pt/C Fuel Cell Catalyst with an X-ray Laboratory Source

2021 ◽  
Author(s):  
Johanna Schröder ◽  
Jonathan Quinson ◽  
Jacob J. K. Kirkensgaard ◽  
Matthias Arenz
Keyword(s):  
Fuel Cell ◽  
Background Subtraction ◽  
Stress Test ◽  
High Surface ◽  
High Surface Area ◽  
Carbon Support ◽  
Grazing Incidence ◽  
Saxs Data ◽  
X Ray ◽  
Fuel Cell Catalysts

Small angle X-ray scattering (SAXS) is a powerful technique to investigate the degradation of catalyst materials. Ideally such investigations are performed <i>operando</i>, i.e., during a catalytic reaction. An example of <i>operando </i>measurements is to observe the degradation of fuel cell catalysts during an accelerated stress test (AST). Fuel cell catalysts consist of Pt or Pt alloy nanoparticles (NPs) supported on a high surface area carbon. A key challenge of operando SAXS measurements is a proper background subtraction of the carbon support to extract the information of the size distribution of the Pt NPs as a function of the AST treatment. Typically, such operando studies require the use of synchrotron facilities. The background measurement can then be performed by anomalous SAXS (aSAXS) or in a grazing incidence con-figuration. In this work we present a proof-of-concept study demonstrating the use of a laboratory X-ray diffractometer for <i>operando </i>SAXS. Data acquisition of <i>operando </i>SAXS with a laboratory X-ray diffractometer is desirable due to the general challenging and limited accessibility of synchrotron facilities. They become even more crucial under the ongoing and foreseen restrictions related to the COVID-19 pandemic. Although, it is not the aim to completely replace synchrotron-based studies, it is shown that the background subtraction can be achieved by a simple experimental consideration in the setup that can ultimately facilitate <i>operando </i>SAXS measurements at a synchrotron facility. <br>

Background subtraction and moments of the microscopic density fluctuation

2002 ◽  
Vol 35 (2) ◽  
pp. 220-227 ◽  
Author(s):  
Roger Sobry ◽  
Salvino Ciccariello
Keyword(s):  
Background Subtraction ◽  
Density Fluctuation ◽  
Density Fluctuations ◽  
Algebraic Expression ◽  
Real Samples ◽  
Background Contribution ◽  
X Ray ◽  
Different Temperatures ◽  
Parameter Values ◽  
Best Fit

Some models of microscopic density fluctuations are numerically analysed in order to study the behaviour of the related background contribution. The results suggest that this contribution can be described by an algebraic expression depending on only the moments of the microscopic density fluctuation. In this way, the parameter values, determined by a best-fit procedure to account for background contributions in the case of real samples, acquire a definite physical meaning. The procedure is applied to the small-angle X-ray intensities of a polymer sample analysed at different temperatures and yields satisfactory results.

scholarly journals SAXS4COLL: an integrated software tool for analysing fibrous collagen-based tissues

2017 ◽  
Vol 50 (4) ◽  
pp. 1235-1240 ◽  
Author(s):  
Ahmed Abass ◽  
James S. Bell ◽  
Martin T. Spang ◽  
Sally Hayes ◽  
Keith M. Meek ◽  
...  
Keyword(s):  
Background Subtraction ◽  
Software Tool ◽  
Peak Detection ◽  
Saxs Data ◽  
X Ray ◽  
Cylindrically Symmetric ◽  
X Ray Scattering ◽  
Integrated Software ◽  
Scattering Systems

This article provides an overview of a new integrated software tool for reduction and analysis of small-angle X-ray scattering (SAXS) data from fibrous collagen tissues, with some wider applicability to other cylindrically symmetric scattering systems.SAXS4COLLcombines interactive features for data pre-processing, bespoke background subtraction, semi-automated peak detection and calibration. Both equatorial and meridional SAXS peak parameters can be measured, and the former can be deconstructed into cylinder and lattice contributions. Finally, the software combines functionality for determination of collagen spatial order parameters with a rudimentary orientation plot capability.

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