Angle-Resolved X-Ray Depth Profiling: Interpretation of Angleresolved Profiles Using a Monte Carlo Approach

1999 ◽  
Vol 5 (S2) ◽  
pp. 582-583
Author(s):  
D.K. Wilkinson ◽  
M. Prutton ◽  
D.A. Loveday
Keyword(s):  
Monte Carlo ◽  
Electron Scattering ◽  
Photoelectron Spectroscopy ◽  
Depth Profiling ◽  
Incident Beam ◽  
Angle Of Incidence ◽  
X Rays ◽  
X Ray ◽  
Interaction Volume ◽  
Depth Profiles

A technique has been developed for the interpretation of composition depth profiles from angleresolved x-ray data using a Monte Carlo electron scattering simulation. Conventional methods for the interpretation of angle-resolved depth profiles used in the fields of x-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) assume that the outgoing signal is exponentially attenuated along its path. This assumption if not valid for angle-resolved x-ray techniques, as the x-ray signal is dependent on both the paths of the incident electrons and the path of the emitted x-rays. In this case, while the latter can be treated using an exponential attenuation, the path of the incident beam is more complex and corresponds to the well known “pear-shaped” interaction volume. In order to reliably interpret angle-resolved depth profiles in which the angle of the incident beam is varied, it is necessary to be able to obtain the distribution of x-ray emission within the sample for any angle of incidence.

Nondestructive Angle-resolved X-ray Depth Profiling: Interpretation of Angle-resolved Profiles Using a Monte Carlo Approach

2000 ◽  
Vol 6 (6) ◽  
pp. 517-531
Author(s):  
David K. Wilkinson ◽  
Daniel A. Loveday ◽  
Martin Prutton
Keyword(s):  
Monte Carlo ◽  
Electron Scattering ◽  
Depth Profiling ◽  
Angle Of Incidence ◽  
Beam Angle ◽  
X Ray ◽  
Depth Profiles ◽  
Custom Made ◽  
Measured Angle ◽  
Composition Depth Profile

AbstractA technique has been developed for the interpretation of composition-depth profiles from angleresolved X-ray data using a Monte Carlo electron scattering simulation. This is a nondestructive depth profiling procedure. Software has been developed that uses a Monte Carlo scattering simulation to generate the signal intensity from a multilayer sample for any combination of primary beam angle of incidence and take-off angle to the X-ray detector. An interactive C++ application uses this simulation to interpret measured angle-resolved depth profiles. The method has been tested using a custom-made Ag/Al “staircase” sample containing two layers each of Ag and Al. Using the technique, it is possible to quantify the composition-depth profile for the two- and three-layer “steps” of the sample. Qualitative information may be gained about the four-layer area of the sample.

Confocal X-ray Fluorescence (XRF) Microscopy: A New Technique for the Nondestructive Compositional Depth Profiling of Paintings

2004 ◽  
Vol 852 ◽  
Author(s):  
Arthur R. Woll ◽  
Donald H. Bilderback ◽  
Sol Gruner ◽  
Ning Gao ◽  
Rong Huang ◽  
...  
Keyword(s):  
Depth Profiling ◽  
Incident Beam ◽  
High Energy ◽  
X Rays ◽  
Oil Painting ◽  
Synchrotron Source ◽  
X Ray ◽  
Glass Slides ◽  
A New Technique ◽  
Paint Films

ABSTRACTA confocal x-ray fluorescence microscope was built at the Cornell High Energy Synchrotron Source (CHESS) to determine the composition of buried paint layers that range from 10–80 μm thick in paintings. The microscope consists of a borosilicate monocapillary optic to focus the incident beam and a borosilicate polycapillary lens to collect the fluorescent x-rays. The overlap of the two focal regions is several tens of microns in extent, and defines the active, or confocal, volume of the microscope. The capabilities of the technique were tested using acrylic paint films with distinct layers brushed onto glass slides and a twentieth century oil painting on canvas. The position and thickness of individual layers were extracted from their fluorescence profiles by fitting to a simple, semi-empirical model.

Surface Analysis of UO2 Leached in Mineral Water Studied by X-Ray Photoelectron Spectroscopy

1988 ◽  
Vol 127 ◽  
Author(s):  
M. P. Lahalle ◽  
J. C. Krupa ◽  
R. Guillaumont ◽  
M. Genet ◽  
G. C. Allen ◽  
...  
Keyword(s):  
Surface Layer ◽  
Uranium Dioxide ◽  
Photoelectron Spectroscopy ◽  
Uranium Oxide ◽  
Mineral Water ◽  
Depth Profiling ◽  
X Rays ◽  
Xps Analysis ◽  
X Ray ◽  
Layer Analysis

ABSTRACTX-rays photoelectron spectroscopy (XPS) analysis has been carried out on uranium dioxide single crystals placed in both deionised or mineral water at 60 °C and 90 °C for a few months. The surface layer on the sample immersed in mineral water at 90 °C was sufficiently thick to mask the presence of uranium in the recorded XPS spectrum. Depth profiling experiments showed that the deposit was ∼ 100 nm in thickness and revealed the formation of a mixed magnesium-uranium oxide region between the bulk UO2 and the outer magnesium- rich layer. Analysis of the aqueous medium following immersion of the UO2 samples showed that the concentration of uranium released to the mineral water was 10 to 100 times lower than that in deionised water.

Prediction of X-ray spatial resolution for SEM and STEM specimens using Monte Carlo methods

1978 ◽  
Vol 36 (1) ◽  
pp. 546-547
Author(s):  
R.G. Faulkner
Keyword(s):  
Monte Carlo ◽  
Spatial Resolution ◽  
Electron Scattering ◽  
Experimental Methods ◽  
Source Size ◽  
Computer Method ◽  
Spherical Particles ◽  
X Rays ◽  
X Ray ◽  
Inclined Beam

Determinations of spatial X-ray resolution in conventional microanalysis in electron probe microanalysers where the beam is perpendicular to a smooth surface are now quite straightforward. However, SEM's and STEM'S are becoming increasingly used methods for performing microanalysis. The specimen arrangement for this sort of work often involves both inclined beam and detector geometries. Under these conditions X-ray correction constants have to be altered due to the changed average path length for the emerging X-rays. The spatial resolution and correction constants peculiar to the new geometry can be physically studied using a Monte Carlo computer method which simulates the trajectories of many electrons as they interact with the specimen.Another attempt to predict resolution and effective take-off angle using single electron scattering theory has been made for thin films. This over estimates the X-ray source size at large foil thicknesses and under estimates at small foil thicknesses. Experimental methods have been devised utilising edges and small, spherical particles.

Low-voltage EDS of magnesium ferrite Dendrites in a FEG-SEM

1996 ◽  
Vol 54 ◽  
pp. 478-479
Author(s):  
Matthew T. Johnson ◽  
Ian M. Anderson ◽  
Jim Bentley ◽  
C. Barry Carter
Keyword(s):  
Monte Carlo ◽  
Quantitative Analysis ◽  
Monte Carlo Simulations ◽  
Cross Section ◽  
Spatial Resolution ◽  
Low Voltage ◽  
Magnesium Ferrite ◽  
X Ray ◽  
Interaction Volume ◽  
Ferrite Spinel

Energy-dispersive X-ray spectrometry (EDS) performed at low (≤ 5 kV) accelerating voltages in the SEM has the potential for providing quantitative microanalytical information with a spatial resolution of ∼100 nm. In the present work, EDS analyses were performed on magnesium ferrite spinel [(MgxFe1−x)Fe2O4] dendrites embedded in a MgO matrix, as shown in Fig. 1. spatial resolution of X-ray microanalysis at conventional accelerating voltages is insufficient for the quantitative analysis of these dendrites, which have widths of the order of a few hundred nanometers, without deconvolution of contributions from the MgO matrix. However, Monte Carlo simulations indicate that the interaction volume for MgFe2O4 is ∼150 nm at 3 kV accelerating voltage and therefore sufficient to analyze the dendrites without matrix contributions.Single-crystal {001}-oriented MgO was reacted with hematite (Fe2O3) powder for 6 h at 1450°C in air and furnace cooled. The specimen was then cleaved to expose a clean cross-section suitable for microanalysis.

Formation of GaN Self-Organized Nanotips by Nanomasking Effect

2001 ◽  
Vol 707 ◽  
Author(s):  
Harumasa Yoshida ◽  
Tatsuhiro Urushido ◽  
Hideto Miyake ◽  
Kazumasa Hiramtsu
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Aspect Ratio ◽  
Formation Mechanism ◽  
High Aspect Ratio ◽  
Photoelectron Spectroscopy ◽  
Nanometer Scale ◽  
Xps Analysis ◽  
X Ray ◽  
Self Organized

ABSTRACTWe have successfully fabricated self-organized GaN nanotips by reactive ion etching using chlorine plasma, and have revealed the formation mechanism. Nanotips with a high density and a high aspect ratio have been formed after the etching. We deduce from X-ray photoelectron spectroscopy (XPS) analysis that the nanotip formation is attributed to nanometer-scale masks of SiO2 on GaN. The structures calculated by Monte Carlo simulation of our formation mechanism are very similar to the experimental nanotip structures.

Uniform Depth Profiling in X-ray Photoelectron Spectroscopy (Electron Spectroscopy for Chemical Analysis)

1978 ◽  
Vol 32 (2) ◽  
pp. 175-177 ◽  
Author(s):  
L. Bradley ◽  
Y. M. Bosworth ◽  
D. Briggs ◽  
V. A. Gibson ◽  
R. J. Oldman ◽  
...  
Keyword(s):  
Chemical Analysis ◽  
Auger Electron Spectroscopy ◽  
Photoelectron Spectroscopy ◽  
Electron Spectroscopy ◽  
Auger Electron ◽  
Depth Profiling ◽  
Ion Source ◽  
X Ray ◽  
Nitride Oxide ◽  
Silicon Device

The difficulties of nonuniform ion etching which hamper depth profiling by X-ray photoelectron spectroscopy (XPS) have been overcome by use of a mechanically scanned saddle-field ion source. The system and its calibration for uniformity are described, and its performance is illustrated by the depth profile of a Si3N4/SiO2/Si metal nitride oxide silicon device. This also allows the potential advantages of XPS profiling over Auger electron spectroscopy profiling to be discussed.

scholarly journals A hydroxyapatite phantom material for the calibration of in vivo x-ray fluorescence systems of bone strontium and lead quantification

2021 ◽  
Author(s):  
Eric Da Silva
Keyword(s):  
Monte Carlo ◽  
Soft Tissue ◽  
Monte Carlo Simulations ◽  
Calibration Procedure ◽  
X Rays ◽  
X Ray ◽  
Total Phosphate Concentration ◽  
High Concentrations ◽  
Phantom Material

A hydroxyaptite [HAp; Ca5(PO4)3OH] phantom material was developed with the goal of improving the calibration protocol of the 125I-induced in vivo X-ray fluorescence (IVXRF) system of bone strontium quantification with further application to other IVXRF bone metal quantification systems, particulary those associated with bone lead quantification. It was found that calcium can be prepared pure of inherent contamination from strontium (and other elements) through a hydroxide precipitation producing pure Ca(OH)2, thereby, allowing for the production of a blank phantom which has not been available previously. The pure Ca(OH)2 can then be used for the preparation of pure CaHPO4 ⋅ 2H2O. A solid state pure HAp phantom can then be prepared by reaction of Ca(OH)2 and CaHPO4 ⋅ 2H2O mixed as to produce a Ca/P mole ratio of 1.67, that in HAp and the mineral phase of bone, in the presence of a setting solution prepared as to raise the total phosphate concentration of the solution by increasing the solubility CaHPO4 ⋅ 2H2O and thereby precipitating HAp. The procedure can only be used to prepare phantoms in which doping with the analyte does not disturb the Ca/P ratio substantially. In cases in which phantoms are to be prepared with high concentrations of strontium, the cement mixture can be modified as to introduce strontium in the form of Sr(OH)2 ⋅ 8H2O as to maintain a (Ca + Sr)/P ratio of 1.67. It was found by both X-ray diffraction spectrometry and Raman spectroscopy studies that strontium substitutes for calcium as in bone when preparing phantoms by this route. The necessity for the blank bone phantoms was assessed through the first blank bone phantom measurement and Monte Carlo simulations. It was found that for the 125I-induced IVXRF system of bone strontium quantification, the source, 125I brachytherapy seeds may be contributing coherently and incoherently scattered zirconium X-rays to the measured spectra, thereby requiring the use of the blank bone phantom as a means of improving the overall quantification methodology. Monte Carlo simulations were employed to evaluate any improvement by the introduction of HAp phantoms into the coherent normalization-based calibration procedure. It was found that HAp phantoms remove the need for a coherent conversion factor (CCF) thereby potentially increasing accuracy of the quantification. Further, it was found that in order for soft tissue attenuation corrections to be possible using spectroscopic information alone, HAp along with a suitable soft tissue surrogate material need to be employed. The HAp phantom material was used for the evaluations of portable X-ray analyzer systems for their potential for IVXRF quantification of lead and strontium with a focus on a comparison between tungsten, silver and rhodium target systems. Silver and rhodium target X-ray tube systems were found to be comparable for this quantification.

scholarly journals Linearly polarized X-ray fluorescence computed tomography based on a Thomson scattering light source: a Monte Carlo study

2020 ◽  
Vol 27 (3) ◽  
pp. 737-745
Author(s):  
Zhijun Chi ◽  
Yingchao Du ◽  
Wenhui Huang ◽  
Chuanxiang Tang
Keyword(s):  
Computed Tomography ◽  
Monte Carlo ◽  
Compton Scattering ◽  
Light Source ◽  
Thomson Scattering ◽  
X Rays ◽  
X Ray ◽  
Pile Up ◽  
Linearly Polarized ◽  
Scattering Light

A Thomson scattering X-ray source can provide quasi-monochromatic, continuously energy-tunable, polarization-controllable and high-brightness X-rays, which makes it an excellent tool for X-ray fluorescence computed tomography (XFCT). In this paper, we examined the suppression of Compton scattering background in XFCT using the linearly polarized X-rays and the implementation feasibility of linearly polarized XFCT based on this type of light source, concerning the influence of phantom attenuation and the sampling strategy, its advantage over K-edge subtraction computed tomography (CT), the imaging time, and the potential pulse pile-up effect by Monte Carlo simulations. A fan beam and pinhole collimator geometry were adopted in the simulation and the phantom was a polymethyl methacrylate cylinder inside which were gadolinium (Gd)-loaded water solutions with Gd concentrations ranging from 0.2 to 4.0 wt%. Compared with the case of vertical polarization, Compton scattering was suppressed by about 1.6 times using horizontal polarization. An accurate image of the Gd-containing phantom was successfully reconstructed with both spatial and quantitative identification, and good linearity between the reconstructed value and the Gd concentration was verified. When the attenuation effect cannot be neglected, one full cycle (360°) sampling and the attenuation correction became necessary. Compared with the results of K-edge subtraction CT, the contrast-to-noise ratio values of XFCT were improved by 2.03 and 1.04 times at low Gd concentrations of 0.2 and 0.5 wt%, respectively. When the flux of a Thomson scattering light source reaches 1013 photons s−1, it is possible to finish the data acquisition of XFCT at the minute or second level without introducing pulse pile-up effects.

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