A Method for Controlling Scattered Radiation in Obtaining X‐Ray Absorption Data by Photographic Means

1946 ◽  
Vol 17 (12) ◽  
pp. 539-542 ◽  
Author(s):  
H. E. Seemann ◽  
L. L. MacGillivray
Keyword(s):  
Scattered Radiation ◽  
Absorption Data ◽  
X Ray ◽  
X Ray Absorption

SIGMAL: A Program for Calculating L-Shell lonization Cross-Sections

1981 ◽  
Vol 39 ◽  
pp. 198-199 ◽  
Author(s):  
R.F. Egerton
Keyword(s):  
Cross Sections ◽  
Fortran Program ◽  
Absorption Data ◽  
X Ray ◽  
Atomic Electrons ◽  
Energy Dependent ◽  
Hydrogenic Model ◽  
Electron Energy Loss ◽  
X Ray Absorption ◽  
Shell Ionization

SIGMAL is a short (∼ 100-line) Fortran program designed to rapidly compute cross-sections for L-shell ionization, particularly the partial crosssections required in quantitative electron energy-loss microanalysis. The program is based on a hydrogenic model, the L1 and L23 subshells being represented by scaled Coulombic wave functions, which allows the generalized oscillator strength (GOS) to be expressed analytically. In this basic form, the model predicts too large a cross-section at energies near to the ionization edge (see Fig. 1), due mainly to the fact that the screening effect of the atomic electrons is assumed constant over the L-shell region. This can be remedied by applying an energy-dependent correction to the GOS or to the effective nuclear charge, resulting in much closer agreement with experimental X-ray absorption data and with more sophisticated calculations (see Fig. 1 ).

Uranium Speciation in Glass Corrosion Layers: an XAFS Study

1996 ◽  
Vol 465 ◽  
Author(s):  
Bruce M. Biwer ◽  
L. Soderholm ◽  
R. B. Greegort ◽  
F. W. Lytle
Keyword(s):  
Corrosion Layer ◽  
Borosilicate Glasses ◽  
Absorption Data ◽  
X Ray ◽  
Surface Sensitivity ◽  
Glass Corrosion ◽  
Uranium Speciation ◽  
Before And After ◽  
X Ray Absorption ◽  
Leaching Surface

ABSTRACTUranium L3 X-ray absorption data were obtained from two borosilicate glasses, which are considered as models for radioactive wasteforms, both before and after leaching. Surface sensitivity to uranium speciation was attained by a novel application of simultaneous fluorescence and electron-yield detection. Changes in speciation are clearly discernible, from U(VI) in the bulk to (UO2)2+-uranyl in the corrosion layer. The uranium concentrations within the corrosion layer also show variations with leaching times that can be determined from the data.

A combined diffraction and EXAFS study of LaCoO3 and La0.5Sr0.5Co0.75Nb0.25O3 powders

2017 ◽  
Vol 32 (S1) ◽  
pp. S52-S55
Author(s):  
E. A. Efimova ◽  
V. V. Sikolenko ◽  
D. V. Karpinsky ◽  
I. O. Troyanchuk ◽  
S. Pascarelli ◽  
...  
Keyword(s):  
Spin State ◽  
State Transition ◽  
X Ray Diffraction ◽  
Absorption Data ◽  
X Ray ◽  
Bond Lengths ◽  
Structural Distortions ◽  
Spin State Transition ◽  
Local Range ◽  
X Ray Absorption

A combination of neutron diffraction, synchrotron X-ray diffraction, and high-resolution extended X-ray absorption fine structure measurements has been used to clarify the correlations between long- and local-range structural distortions across the spin-state transition in powders of LaCoO3 and La0.5Sr0.5Co0.75Nb0.25O3. The analysis of the diffraction data has revealed that the isotropic thermal parameters of Co–O bond abnormally increase below 100 K in both samples, while the temperature dependence of the average Co–O bond lengths is linear from 10 to 300 K. We also have found that the Co–O bond lengths are larger in La0.5Sr0.5Co0.75Nb0.25O3, as compared with the ones in LaCoO3. The X-ray absorption data showed an anomalous decrease of the Co–O bond lengths only for LaCoO3, in contrast to the bond length values obtained by diffraction. The structural anomalies observed by spectroscopy measurements are discussed in terms of the spin-state transition model.

Changing Np Redox Speciation in the Synchrotron Beam

2003 ◽  
Vol 802 ◽  
Author(s):  
S. Skanthakumar ◽  
D. Gorman-Lewis ◽  
A. Locock ◽  
M.-H. Chiang ◽  
M. P. Jensen ◽  
...  
Keyword(s):  
Metal Ion ◽  
Absorption Data ◽  
X Ray ◽  
Synchrotron Beam ◽  
Show Evidence ◽  
X Ray Absorption ◽  
Redox Speciation

ABSTRACTX-ray absorption data, obtained from Np(V) in two environmentally-related samples, show evidence of significant metal-ion reduction in the synchrotron beam. The data are presented and possible sources of reduction are discussed.

scholarly journals Wavelet investigation of La0.5Ca0.5CoO3−δ x-ray absorption data

2007 ◽  
Vol 101 (1) ◽  
pp. 014911 ◽  
Author(s):  
M. Sahnoun ◽  
C. Daul ◽  
O. Haas
Keyword(s):  
Absorption Data ◽  
X Ray ◽  
X Ray Absorption

Bayes-Turchin analysis of x-ray absorption data above the FeL2,3-edges

2006 ◽  
Vol 74 (13) ◽  
Author(s):  
H. H. Rossner ◽  
D. Schmitz ◽  
P. Imperia ◽  
H. J. Krappe ◽  
J. J. Rehr
Keyword(s):  
Absorption Data ◽  
X Ray ◽  
X Ray Absorption

Distorted f.c.c. arrangement of gold nanoclusters: a model of spherical particles with microstrains and stacking faults

2008 ◽  
Vol 41 (2) ◽  
pp. 446-455 ◽  
Author(s):  
Alessandro Longo ◽  
Antonino Martorana
Keyword(s):  
Experimental Data ◽  
Linear Combination ◽  
Gold Nanoclusters ◽  
Stacking Faults ◽  
Basis Set ◽  
Spherical Particles ◽  
Absorption Data ◽  
X Ray ◽  
Two Samples ◽  
X Ray Absorption

The structures of two samples of gold nanoclusters supported on silica were studied by X-ray powder diffraction (XRD) and X-ray absorption spectroscopy. The data relative to both techniques were analysed by an approach involving simulation based on structural models and fitting. The XRD model concerned a distorted f.c.c. (face-centred cubic) arrangement, with microstrains and parallel stacking faults in approximately spherical particles; as an alternative possibility, a linear combination of ordered f.c.c. and noncrystalline (decahedral and icosahedral) particles was also taken into account. Both approaches gave calculated patterns closely resembling the experimental data. X-ray absorption spectra were fitted on the basis of f.c.c. and noncrystalline arrangements. The best results were obtained by the f.c.c. motif, while a simulation consisting in the superposition of f.c.c. and noncrystalline components in the relative amounts determined by XRD analysis gave a poor agreement with the experimental data. It was concluded that the good XRD fitting obtained by linear combination of lognormal size-distributed f.c.c. cuboctahedral, decahedral and icosahedral contributions was a result of the flexibility of the basis set of functions, but that the complementary analysis of X-ray absorption data did not confirm the presence of a noteworthy fraction of noncrystalline particles.

Fast continuous energy scan with dynamic coupling of the monochromator and undulator at the DEIMOS beamline

2014 ◽  
Vol 21 (3) ◽  
pp. 502-506 ◽  
Author(s):  
L. Joly ◽  
E. Otero ◽  
F. Choueikani ◽  
F. Marteau ◽  
L. Chapuis ◽  
...  
Keyword(s):  
Dead Time ◽  
Data Recording ◽  
Dynamic Coupling ◽  
Time Loss ◽  
Absorption Data ◽  
Continuous Motion ◽  
X Ray ◽  
Continuous Energy ◽  
X Ray Absorption ◽  
Beam Characteristics

In order to improve the efficiency of X-ray absorption data recording, a fast scan method, theTurboscan, has been developed on the DEIMOS beamline at Synchrotron SOLEIL, consisting of a software-synchronized continuous motion of the monochromator and undulator motors. This process suppresses the time loss when waiting for the motors to reach their target positions, as well as software dead-time, while preserving excellent beam characteristics.

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