L3-subshell alignment of Ag in collision with 15 keV electrons

2020 ◽  
Vol 28 (5) ◽  
pp. 1017-1023
Author(s):  
Pengfei Hu ◽  
Xing Wang
Keyword(s):  
Spatial Distribution ◽  
Electron Impact ◽  
Legendre Polynomial ◽  
Anisotropy Parameter ◽  
Collision Process ◽  
X Ray ◽  
Atomic Ionization ◽  
Elementary Analysis ◽  
Intensity Ratios ◽  
Anisotropic Emission

It is of great importance to study the alignment of atoms in collision process in elementary analysis with a Particle Induced X-ray Emission (PIXE) technique. The measurement of alignment can also offer an effective testing ground for developing theory models in ionization process. The typical L X-ray spectra are measured for Ag thin target by 15 keV electron impact at emission angles from 0° to 25°. Angular dependence of intensity ratios Lα/Lβ1, Lβ2/Lβ1 and Lγ/Lβ1 are investigated as a function of the second-order Legendre polynomial P2(cosθ). This study found that Lβ2 line exhibits anisotropic emission spatially, while the emission of Lα, Lβ1 and Lγ1 lines is isotropic. The results are interpreted by the influence of the Coster-Kronig (CK) transitions on the spatial distribution of X-ray emission. The anisotropy parameter β for Lβ2 lines is obtained experimentally and consequently the alignment degree A20 for L3 subshell is determined by taking CK transition into account. Namely, the alignment does exist in L3-subshell for atomic ionization by electron impact. The measurements offer an evidence to the existence of alignment for atomic ionization in electron-impact process.

Influence of X-Ray Induced Fluorescence on Energy Dispersive X-Ray Analysis of Thin Foils

1977 ◽  
Vol 35 ◽  
pp. 328-329
Author(s):  
E. A. Kenik ◽  
J. Bentley
Keyword(s):  
Thin Foil ◽  
Electron Excitation ◽  
Simple Approach ◽  
Foil Thickness ◽  
X Rays ◽  
X Ray ◽  
Hole Spectrum ◽  
Illumination System ◽  
Thin Foils ◽  
Intensity Ratios

Cliff and Lorimer (1) have proposed a simple approach to thin foil x-ray analy sis based on the ratio of x-ray peak intensities. However, there are several experimental pitfalls which must be recognized in obtaining the desired x-ray intensities. Undesirable x-ray induced fluorescence of the specimen can result from various mechanisms and leads to x-ray intensities not characteristic of electron excitation and further results in incorrect intensity ratios.In measuring the x-ray intensity ratio for NiAl as a function of foil thickness, Zaluzec and Fraser (2) found the ratio was not constant for thicknesses where absorption could be neglected. They demonstrated that this effect originated from x-ray induced fluorescence by blocking the beam with lead foil. The primary x-rays arise in the illumination system and result in varying intensity ratios and a finite x-ray spectrum even when the specimen is not intercepting the electron beam, an ‘in-hole’ spectrum. We have developed a second technique for detecting x-ray induced fluorescence based on the magnitude of the ‘in-hole’ spectrum with different filament emission currents and condenser apertures.

Macroprobe Mode for the Study of Segregation in Steels

1990 ◽  
Vol 48 (2) ◽  
pp. 260-261
Author(s):  
Auclair Gilles ◽  
Benoit Danièle
Keyword(s):  
Mechanical Properties ◽  
Spatial Distribution ◽  
High Performance ◽  
Volume Fraction ◽  
Sheet Steel ◽  
Acquisition Time ◽  
Chemical Information ◽  
X Ray ◽  
Accurate Quantitative Analysis ◽  
Optical Micrographs

During these last 10 years, high performance correction procedures have been developed for classical EPMA, and it is nowadays possible to obtain accurate quantitative analysis even for soft X-ray radiations. It is also possible to perform EPMA by adapting this accurate quantitative procedures to unusual applications such as the measurement of the segregation on wide areas in as-cast and sheet steel products.The main objection for analysis of segregation in steel by means of a line-scan mode is that it requires a very heavy sampling plan to make sure that the most significant points are analyzed. Moreover only local chemical information is obtained whereas mechanical properties are also dependant on the volume fraction and the spatial distribution of highly segregated zones. For these reasons we have chosen to systematically acquire X-ray calibrated mappings which give pictures similar to optical micrographs. Although mapping requires lengthy acquisition time there is a corresponding increase in the information given by image anlysis.

scholarly journals A physico-chemical model to study the ion density distribution in the inner coma of comet C/2016 R2 (Pan-STARRS)

2020 ◽  
Author(s):  
Susarla Raghuram ◽  
Anil Bhardwaj ◽  
Damien Hutsemékers ◽  
Cyrielle Opitom ◽  
Jean Manfroid ◽  
...  
Keyword(s):  
Density Distribution ◽  
Electron Impact ◽  
Emission Intensity ◽  
Impact Ionization ◽  
Excitation Source ◽  
Resonance Fluorescence ◽  
Ion Density ◽  
Physico Chemical ◽  
Intensity Ratios ◽  
Ion Emission

Abstract The recent observations show that comet C/2016 R2 (Pan-Starrs) has a unique and peculiar composition when compared with several other comets observed at 2.8 au heliocentric distance. Assuming solar resonance fluorescence is the only excitation source, the observed ionic emission intensity ratios are used to constrain the corresponding neutral abundances in this comet. We developed a physico-chemical model to study the ion density distribution in the inner coma of this comet by accounting for photon and electron impact ionization of neutrals, charge exchange and proton transfer reactions between ions and neutrals, and electron-ion thermal recombination reactions. Our calculations show that CO$_2^+$ and CO+ are the major ions in the inner coma, and close to the surface of nucleus CH3OH+, CH3OH$_2^+$ and O$_2^+$ are also important ions. By considering various excitation sources, we also studied the emission mechanisms of different excited states of CO+, CO$_2^+$, N$_2^+$, and H2O+. We found that the photon and electron impact ionization and excitation of corresponding neutrals significantly contribute to the observed ionic emissions for radial distances smaller than 300 km and at larger distances, solar resonance fluorescence is the major excitation source. Our modelled ion emission intensity ratios are consistent with the ground-based observations. Based on the modelled emission processes, we suggest that the observed ion emission intensity ratios can be used to derive the neutral composition in the cometary coma only when the ion densities are significantly controlled by photon and photoelectron impact ionization of neutrals rather than by the ion-neutral chemistry.

K shell X-ray intensity ratios, K-Li, K-L, and K-M vacancy transfer probabilities of Ba and Tl following internal conversion process

2014 ◽  
Vol 92 (11) ◽  
pp. 1489-1493 ◽  
Author(s):  
P.V. Sreevidya ◽  
S.B. Gudennavar ◽  
Daisy Joseph ◽  
S.G. Bubbly
Keyword(s):  
Beta Decay ◽  
Internal Conversion ◽  
Experimental Results ◽  
Conversion Process ◽  
X Rays ◽  
X Ray ◽  
Multichannel Analyser ◽  
Intensity Ratios

K shell X-rays of barium and thallium following internal conversion decay in Cs137 and Hg203, respectively, were detected using a Si(Li) X-ray detector coupled to PC-based 8k multichannel analyser employing the method suggested earlier by our group. The K shell X-ray intensity ratios and vacancy transfer probabilities for thallium and barium were calculated. The obtained results are compared with theoretical, semiempirical, and others’ experimental results obtained via photoionization as well as decay processes. The effects of beta decay and internal conversion on X-ray emission probabilities are discussed.

K-shell X-ray intensity ratios and vacancy transfer probabilities of Pt, Au, and Pb by a simple method

2014 ◽  
Vol 119 (3) ◽  
pp. 392-397 ◽  
Author(s):  
L. F. M. Anand ◽  
S. B. Gudennavar ◽  
S. G. Bubbly ◽  
B. R. Kerur
Keyword(s):  
Simple Method ◽  
X Ray ◽  
Intensity Ratios

Element-specific structural analysis of Si/B4C using resonant X-ray reflectivity

2015 ◽  
Vol 48 (3) ◽  
pp. 786-796 ◽  
Author(s):  
Maheswar Nayak ◽  
P. C. Pradhan ◽  
G. S. Lodha
Keyword(s):  
Thin Film ◽  
Spatial Distribution ◽  
Structural Analysis ◽  
Chemical Changes ◽  
X Ray ◽  
Buried Interfaces ◽  
Smooth Interface ◽  
Specific Composition ◽  
Applied Fields ◽  
Spatial Modulations

Element-specific structural analysis at the buried interface of a low electron density contrast system is important in many applied fields. The analysis of nanoscaled Si/B4C buried interfaces is demonstrated using resonant X-ray reflectivity. This technique combines information about spatial modulations of charges provided by scattering, which is further enhanced near the resonance, with the sensitivity to electronic structure provided by spectroscopy. Si/B4C thin-film structures are studied by varying the position of B4C in Si layers. Measured values of near-edge optical properties are correlated with the resonant reflectivity profile to quantify the element-specific composition. It is observed that, although Si/B4C forms a smooth interface, there are chemical changes in the sputtered B4C layer. Nondestructive quantification of the chemical changes and the spatial distribution of the constituents is reported.

Sign in / Sign up

Export Citation Format

Share Document