X-Ray Fluorescence Cross-Section Measurements in the Energy Range 4-18 keV

1995 ◽  
Vol 39 ◽  
pp. 845-855
Author(s):  
Krassimir N. Stoev ◽  
Joseph F. Dlouhy
Keyword(s):  
Cross Sections ◽  
Transition Probabilities ◽  
Weighted Average ◽  
Physical Parameters ◽  
Emission Rates ◽  
Excitation Energies ◽  
X Ray ◽  
Fluorescence Cross Section ◽  
Theoretical Results

K, L and M shell x-ray fluorescence cross sections have been measured for elements 11 ≤, Z ≤, 92 at excitation energies corresponding to weighted average energies of K-lines of Ti-K (4.558 keV), Fe-K (6,480 keV), Ge-K (10.024 keV), Se-K (11.391 keV) and Mo-K (17.805 keV) . The measurements were performed with an energy-dispersive x-ray spectrometer in a vacuum chamber using thin ultra-pure targets. Rh x-ray tube and secondary targets were used for excitation of x-ray radiation. The measured x-ray fluorescence cross-sections have been compared to previously published experimental and theoretical results. Presented data can be used for determination of physical parameters such as photoionization cross-sections, fluorescence yields, x-ray emission rates, Coster-Kronig transition probabilities and jump ratios.

CHOICE OF ATOMIC PARAMETERS FOR THEORETICAL CALCULATIONS OF L X-RAY PRODUCTION CROSS SECTIONS

1993 ◽  
Vol 03 (01) ◽  
pp. 45-61 ◽  
Author(s):  
RAVINDER KAUR ◽  
SATINDER SINGH
Keyword(s):  
Cross Sections ◽  
Transition Probabilities ◽  
Theoretical Calculations ◽  
Production Cross ◽  
Emission Rates ◽  
Excitation Energies ◽  
X Ray ◽  
Experimental Values ◽  
Atomic Parameters

Photon-induced L X-ray production cross sections have been calculated for even Z in the region Z=40–92 at different excitation energies. The results have been compared with the experimental values, and the effects of the choice of atomic parameters — like fluorescence yields, Coster-Kroning transition probabilities and relative emission rates — used in calculating L X-ray production cross sections have been discussed.

scholarly journals How do Uncertainties in Atomic Parameters Influence Theoretical Predictions of X-Ray Production Cross Sections By Proton Impact?

2020 ◽  
Vol 7 (2) ◽  
pp. 71-76
Author(s):  
J Miranda
Keyword(s):  
Cross Sections ◽  
Transition Probabilities ◽  
Production Cross ◽  
Emission Rates ◽  
X Rays ◽  
X Ray ◽  
Proton Impact ◽  
Analytical Technique ◽  
Ionization Cross Sections ◽  
Atomic Parameters

The emission of characteristic X-rays induced by proton impact is a phenomenon known since the first half of the 20th century. Its more widely known application is the analytical technique Particle Induced X-ray Emission (PIXE). Several models have been developed to calculate, first, ionization cross sections and then the subsequent X-ray production cross sections. However, to carry out the comparisons of these predictions with experimental data it is necessary to use atomic parameters databases (fluorescence yields, Coster-Kronig transition probabilities, emission rates) that also have experimental uncertainties. In this work it is demonstrated how these values do not allow to decide which model describes more accurately the cross sections, due to a final “theoretical uncertainty” obtained through the propagation of the original uncertainties.

Preparation And elemental analysis of ancient fibers

1987 ◽  
Vol 45 ◽  
pp. 410-411
Author(s):  
Allen Angel ◽  
Kathryn A. Jakes
Keyword(s):  
Cross Sections ◽  
Physical Structure ◽  
Energy Dispersive ◽  
Archaeological Sites ◽  
X Ray ◽  
Long Term Storage ◽  
Backscattered Electron ◽  
Electron Imaging

Fabrics recovered from archaeological sites often are so badly degraded that fiber identification based on physical morphology is difficult. Although diagenetic changes may be viewed as destructive to factors necessary for the discernment of fiber information, changes occurring during any stage of a fiber's lifetime leave a record within the fiber's chemical and physical structure. These alterations may offer valuable clues to understanding the conditions of the fiber's growth, fiber preparation and fabric processing technology and conditions of burial or long term storage (1).Energy dispersive spectrometry has been reported to be suitable for determination of mordant treatment on historic fibers (2,3) and has been used to characterize metal wrapping of combination yarns (4,5). In this study, a technique is developed which provides fractured cross sections of fibers for x-ray analysis and elemental mapping. In addition, backscattered electron imaging (BSI) and energy dispersive x-ray microanalysis (EDS) are utilized to correlate elements to their distribution in fibers.

Measurement Of Relative X-Ray Intensity Ratios for Elements With Z=14 to 92 Using EDXRF Spectrometer

1993 ◽  
Vol 37 ◽  
pp. 697-709 ◽  
Author(s):  
Krassimir N. Stoev ◽  
Joseph F. Dlouhy
Keyword(s):  
Fluorescence Analysis ◽  
Radiative Transition ◽  
Published Data ◽  
Emission Rates ◽  
Experimental Physics ◽  
X Ray ◽  
Overlapped Peaks ◽  
Intensity Ratios ◽  
Atomic Structure Calculations

Nowadays x-ray fluorescence analysis is one of the major techniques for determination of trace elements. Vacuum operated Si (Li) .energy-dispersive x-ray spectrometers can analyze simultaneously up to 50 elements from Na (Z=11) to U (Z = 92) . Proper interpretation of the accumulated spectra requires correct solution of x-ray line overlap problems. In many cases knowledge of x-ray intensity ratios can make the procedure for resolving the overlapped peaks more reliable and reproducible. Measurements of radiative transition rates can also provide fundamental tests of theoretical atomic structure calculations. There are many other useful applications of x-ray emission rates in theoretical and experimental physics. On the other hand, there are differences in the published data, which suggests that x-ray intensity ratios are still not known with the necessary accuracy, and new measurements are useful and necessary.

scholarly journals Experimental determination of line energies, line widths and relative transition probabilities of the Gadolinium L x-ray emission spectrum

Metrologia ◽  
2019 ◽  
Vol 56 (6) ◽  
pp. 065007
Author(s):  
Malte Wansleben ◽  
Yves Kayser ◽  
Philipp Hönicke ◽  
Ina Holfelder ◽  
André Wählisch ◽  
...  
Keyword(s):  
Emission Spectrum ◽  
Experimental Determination ◽  
Transition Probabilities ◽  
X Ray ◽  
Relative Transition ◽  
Line Widths

Extended x-ray-absorption fine-structure technique. III. Determination of physical parameters

1975 ◽  
Vol 11 (12) ◽  
pp. 4836-4846 ◽  
Author(s):  
E. A. Stern ◽  
D. E. Sayers ◽  
F. W. Lytle
Keyword(s):  
Fine Structure ◽  
Physical Parameters ◽  
X Ray ◽  
Absorption Fine ◽  
X Ray Absorption

Destruction of C2H4O2 isomers in ice-phase by X-rays: Implication on the abundance of acetic acid and methyl formate in the interstellar medium

2017 ◽  
Vol 13 (S332) ◽  
pp. 418-424
Author(s):  
Marina G. Rachid ◽  
K. Faquine ◽  
S. Pilling
Keyword(s):  
Acetic Acid ◽  
Cross Sections ◽  
Methyl Formate ◽  
X Rays ◽  
Formation Cross Section ◽  
X Ray ◽  
Synchrotron Light ◽  
The Difference ◽  
Astrophysical Ices

AbstractC2H4O2 isomers, methyl formate (HCOOCH3), acetic acid (CH3COOH) and glycoaldehyde (HOCH2CHO), have been detected in a lot of sources in ISM. However, their abundances are very different, with methyl formate much more abundant than the other two isomers. This fact may be related to the different destruction by ionizing radiation of these molecules. The goal of this work is experimentally study the photodissociation processes of methyl formate and acetic acid ices when exposed to broadband soft X-ray from 6 up to 2000 eV. The experiments were performed coupled to the SGM beamline in the Brazilian Synchrotron Light Source (LNLS/CNPEM) at Campinas, Brazil. The simulated astrophysical ices (12K) were monitored throughout the experiment using infrared vibrational spectroscopy. The analysis of processed ices allowed the determination of the effective destruction cross sections of the parent molecules as well as the effective formation cross section of daughter molecular species. The relative abundance between acetic acid and methyl formate (NCH3COOH/NHCOOCH3) in different astronomical scenarios and their column density evolution in the presence of X-rays were calculated and our results suggests that such radiation field can be one of the factors that explain the difference in the isomers C2H4O2 abundances. We also quantified the daugther species after the establishment of a chemical equilibrium in the samples.

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