New approach to the x-ray-absorption problem

1981 ◽  
Vol 24 (8) ◽  
pp. 4863-4866 ◽  
Author(s):  
Luiz N. Oliveira ◽  
John W. Wilkins
Keyword(s):  
New Approach ◽  
X Ray ◽  
X Ray Absorption

In situ back-side illumination fluorescence XAFS (BI-FXAFS) studies on platinum nanoparticles deposited on a HOPG surface as a model fuel cell: a new approach to the Pt-HOPG electrode/electrolyte interface

2014 ◽  
Vol 16 (27) ◽  
pp. 13748-13754 ◽  
Author(s):  
Hiromitsu Uehara ◽  
Yohei Uemura ◽  
Takafumi Ogawa ◽  
Kentaro Kono ◽  
Ryoichi Ueno ◽  
...  
Keyword(s):  
Fine Structure ◽  
Fuel Cell ◽  
Back Side ◽  
New Approach ◽  
X Ray ◽  
Model Fuel ◽  
Fluorescence Xafs ◽  
X Ray Absorption ◽  
Side Illumination

We measured the in situ polarization-dependent X-ray absorption fine structure of PtNPs deposited on a flat HOPG substrate.

High-accuracy X-ray absorption spectra from mMsolutions of nickel (II) complexes with multiple solutions using transmission XAS

2015 ◽  
Vol 22 (4) ◽  
pp. 1008-1021 ◽  
Author(s):  
Christopher T. Chantler ◽  
M. Tauhidul Islam ◽  
Stephen P. Best ◽  
Lachlan J. Tantau ◽  
Chanh Q. Tran ◽  
...  
Keyword(s):  
Multiple Solutions ◽  
High Accuracy ◽  
Hybrid Technique ◽  
Edge Structure ◽  
New Approach ◽  
X Ray ◽  
Square Planar ◽  
Transmission Measurements ◽  
First Time ◽  
X Ray Absorption

A new approach is introduced for determining X-ray absorption spectroscopy (XAS) spectra on absolute and relative scales using multiple solutions with different concentrations by the characterization and correction of experimental systematics. This hybrid technique is a development of standard X-ray absorption fine structure (XAFS) along the lines of the high-accuracy X-ray extended range technique (XERT) but with applicability to solutions, dilute systems and cold cell environments. This methodology has been applied to determining absolute XAS of bis(N-n-propyl-salicylaldiminato) nickel(II) and bis(N-i-propyl-salicylaldiminato) nickel(II) complexes with square planar and tetrahedral structures in 15 mMand 1.5 mMdilute solutions. It is demonstrated that transmission XAS from dilute systems can provide excellent X-ray absorption near-edge structure (XANES) and XAFS spectra, and that transmission measurements can provide accurate measurement of subtle differences including coordination geometries. For the first time, (transmission) XAS of the isomers have been determined from low-concentration solutions on an absolute scale with a 1–5% accuracy, and with relative precision of 0.1% to 0.2% in the active XANES and XAFS regions after inclusion of systematic corrections.

scholarly journals Non-negative matrix analysis for effective feature extraction in X-ray spectromicroscopy

2014 ◽  
Vol 171 ◽  
pp. 357-371 ◽  
Author(s):  
Rachel Mak ◽  
Mirna Lerotic ◽  
Holger Fleckenstein ◽  
Stefan Vogt ◽  
Stefan M. Wild ◽  
...  
Keyword(s):  
Large Scale ◽  
Environmental Science ◽  
Matrix Analysis ◽  
Matrix Approximation ◽  
New Approach ◽  
X Ray ◽  
Rich Information ◽  
Preliminary Study ◽  
X Ray Absorption ◽  
Calculated Image

X-Ray absorption spectromicroscopy provides rich information on the chemical organization of materials down to the nanoscale. However, interpretation of this information in studies of “natural” materials such as biological or environmental science specimens can be complicated by the complex mixtures of spectroscopically complicated materials present. We describe here the shortcomings that sometimes arise in previously-employed approaches such as cluster analysis, and we present a new approach based on non-negative matrix approximation (NNMA) analysis with both sparseness and cluster-similarity regularizations. In a preliminary study of the large-scale biochemical organization of human spermatozoa, NNMA analysis delivers results that nicely show the major features of spermatozoa with no physically erroneous negative weightings or thicknesses in the calculated image.

scholarly journals Signatures of technetium oxidation states: a new approach

2020 ◽  
Vol 56 (67) ◽  
pp. 9608-9611
Author(s):  
Stephen Bauters ◽  
Andreas C. Scheinost ◽  
Katja Schmeide ◽  
Stephan Weiss ◽  
Kathy Dardenne ◽  
...  
Keyword(s):  
Oxidation State ◽  
Oxidation States ◽  
General Strategy ◽  
New Approach ◽  
X Ray ◽  
X Ray Absorption

A general strategy for the determination of Tc oxidation state by a new approach involving X-ray absorption near edge spectroscopy (XANES) at the Tc L3 edge is shown.

Calculating absorption dose when X-ray irradiation modifies material quantity and chemistry

2021 ◽  
Vol 28 (3) ◽  
Author(s):  
Viatcheslav Berejnov ◽  
Boris Rubinstein ◽  
Lis G. A. Melo ◽  
Adam P. Hitchcock
Keyword(s):  
Chemical Speciation ◽  
New Approach ◽  
X Ray ◽  
Scanning Transmission ◽  
Versatile Tool ◽  
Solid Film ◽  
Simplifying Assumptions ◽  
High Doses ◽  
Sensitive Parameters ◽  
X Ray Absorption

X-ray absorption is a sensitive and versatile tool for chemical speciation. However, when high doses are used, the absorbed energy can change the composition, amount and structure of the native material, thereby changing the aspects of the absorption process on which speciation is based. How can one calculate the dose when X-ray irradiation affects the chemistry and changes the amount of the material? This paper presents an assumption-free approach which can retrieve from the experimental data all dose-sensitive parameters – absorption coefficients, composition (elemental molecular units), material densities – which can then be used to calculate accurate doses as a function of irradiation. This approach is illustrated using X-ray damage to a solid film of a perfluorosulfonic acid fluoropolymer in a scanning transmission soft X-ray microscope. This new approach is compared against existing dose models which calculate the dose by making simplifying assumptions regarding the material quantity, density and chemistry. While the detailed measurements used in this approach go beyond typical methods to experimental analytical X-ray absorption, they provide a more accurate quantitation of radiation dose, and help to understand mechanisms of radiation damage.

Controlling Length of Gold Nanorods and Monitoring Their Growth Mechanism Using X-ray Absorption Spectroscopy

2006 ◽  
Vol 921 ◽  
Author(s):  
Ru-Shi Liu ◽  
H. M. Chen ◽  
S. F. Hu
Keyword(s):  
Ascorbic Acid ◽  
Fine Structure ◽  
Absorption Spectroscopy ◽  
Growth Mechanism ◽  
Gold Nanorods ◽  
New Approach ◽  
Growth Solution ◽  
X Ray ◽  
Aspect Ratios ◽  
X Ray Absorption

AbstractA new approach to fabricate long length of gold nanorods by controlling the volume of growth solution will be reported. The shape evolutions ranging from fusiform nanoparticles to 1-D rods was observed. Increasing the addition of growth solution can control the length of nanorods. The length of rods can be extended to 2 £gm, and nanorods with aspect ratios of up to ~ 70 could be obtained. Moreover, X-ray absorption spectroscopy (XAS) is applied herein to elucidate the growth mechanism of gold nanorods. The gold ions were directly reduced to gold atoms by ascorbic acid during the reaction, and then gold atoms were deposited on the surface of gold seeds that were introduced into the reaction. Extended X-ray absorption fine structure (EXAFS) confirmed the growth of gold and the environment around Au atoms over the reaction. The XAS are expected to have wide applications in the growth of gold and other related materials.

scholarly journals Composition-dependent structure of polycrystalline magnetron-sputtered V–Al–C–N hard coatings studied by XRD, XPS, XANES and EXAFS

2013 ◽  
Vol 46 (4) ◽  
pp. 1064-1075 ◽  
Author(s):  
Bärbel Krause ◽  
Susan Darma ◽  
Marthe Kaufholz ◽  
Stefan Mangold ◽  
Stephen Doyle ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Hard Coatings ◽  
X Ray Diffraction ◽  
High Carbon ◽  
High Carbon Content ◽  
New Approach ◽  
X Ray ◽  
Complementary Methods ◽  
Coexisting Phases ◽  
X Ray Absorption

V–Al–C–N hard coatings with high carbon content were deposited by reactive radio-frequency magnetron sputtering using an experimental combinatorial approach, deposition from a segmented sputter target. The composition-dependent coexisting phases within the coating were analysed using the complementary methods of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray absorption near-edge spectroscopy (XANES) and extended X-ray absorption fine-structure spectroscopy (EXAFS). For the analysis of the X-ray absorption near-edge spectra, a new approach for evaluation of the pre-edge peak was developed, taking into account the self-absorption effects in thin films. Within the studied composition range, a mixed face-centred cubic (V,Al)(C,N) phase coexisting with a C–C-containing phase was observed. No indication of hexagonal (V,Al)(N,C) was found. The example of V–Al–C–N demonstrates how important a combination of complementary methods is for the detection of coexisting phases in complex multi-element coatings.

An X-Ray Absorption Method for Elemental Analysis

1963 ◽  
Vol 7 ◽  
pp. 318-324
Author(s):  
K. T. Knapp ◽  
R. H. Lindahl ◽  
A. J. Mabis
Keyword(s):  
Calibration Curve ◽  
Weight Fraction ◽  
Absorption Analysis ◽  
Absorption Method ◽  
Target Element ◽  
New Approach ◽  
X Ray ◽  
Pure Solvent ◽  
X Ray Absorption ◽  
Absorption Measurements

AbstractA new approach to X-ray absorption analysis is presented in this paper. The equation log (I2/I1) = KWA + KB is used, from which the weight fraction WA of a given element can be calculated in various solvents when only a calibration curve from one solvent and the absorption of the new solvent at two wavelengths (λ1 and λ2) are known.This treatment uses the absorption at two wavelengths, one on each side of an absorption edge of the element under study. The desired wavelengths can be conveniently obtained from the Kα and Kβ radiation of an element with an atomic number just higher than the element under study. An easy way to accomplish this is to use the desired target element as the sample in an X-ray spectrometer. The Kα and Kβ radiations are then resolved with an appropriate analyzing crystal, and the absorption measurements are made consecutively.The advantages of this approach are twofold. First, it is only necessary to do a full calibration curve in one solvent; calibration in other solvents can be calculated with only a knowledge of the absorption of that pure solvent at the wavelengths used, which can. either be determined experimentally or calculated. Secondly, the required experimental data can be collected very conveniently in an X-ray spectrometer.

X-ray microanalysis of thin specimens in the transmission electron microscope at voltages up to 1000 Kv.

1978 ◽  
Vol 36 (1) ◽  
pp. 540-541
Author(s):  
G. Cliff ◽  
M.J. Nasir ◽  
G.W. Lorimer ◽  
N. Ridley
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Weight Fraction ◽  
Present Series ◽  
Constant Independent ◽  
X Ray ◽  
Transmission Electron ◽  
Series Of Experiments ◽  
Image Position ◽  
X Ray Absorption

In a specimen which is transmission thin to 100 kV electrons - a sample in which X-ray absorption is so insignificant that it can be neglected and where fluorescence effects can generally be ignored (1,2) - a ratio of characteristic X-ray intensities, I1/I2 can be converted into a weight fraction ratio, C1/C2, using the equationwhere k12 is, at a given voltage, a constant independent of composition or thickness, k12 values can be determined experimentally from thin standards (3) or calculated (4,6). Both experimental and calculated k12 values have been obtained for K(11<Z>19),kα(Z>19) and some Lα radiation (3,6) at 100 kV. The object of the present series of experiments was to experimentally determine k12 values at voltages between 200 and 1000 kV and to compare these with calculated values.The experiments were carried out on an AEI-EM7 HVEM fitted with an energy dispersive X-ray detector.

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