MATRIX EFFECTS ON K-SHELL IONIZATION CROSS SECTIONS IN Al/Si ALLOYS

2002 ◽  
Vol 12 (01n02) ◽  
pp. 1-5
Author(s):  
M. NEKAB ◽  
Ch. HEITZ
Keyword(s):  
Cross Sections ◽  
Matrix Effects ◽  
Production Cross ◽  
Heavy Ion ◽  
Double Scattering ◽  
Scattering Mechanism ◽  
Ionization Cross ◽  
X Ray ◽  
Ionization Cross Sections ◽  
Shell Ionization

Thick targets consisting in Al/Si alloys were bombarded with 1.0 to 5.0 MeV Ar ions. The K X-ray production cross sections were deduced from the measured yields by using the Merzbacher-Lewis formula extended to heavy ion bombardment. The density dependence on the K X-ray production cross sections of Al and Si was observed. This phenomena can be interpreted within the molecular orbital double-scattering mechanism.

K-shell ionization cross sections of K and Lα X-ray production cross sections of I by 10–30 keV electron impact

2012 ◽  
Vol 90 (2) ◽  
pp. 125-130 ◽  
Author(s):  
Y. Wu ◽  
Z. An ◽  
Y.M. Duan ◽  
M.T. Liu ◽  
X.P. Ouyang
Keyword(s):  
Experimental Data ◽  
Electron Impact ◽  
Cross Sections ◽  
Production Cross ◽  
Carbon Substrate ◽  
Ionization Cross ◽  
X Ray ◽  
Pure Carbon ◽  
Ionization Cross Sections ◽  
Shell Ionization

The absolute K-shell ionization cross sections of K and Lα X-ray production cross sections of I by 10–30 keV electron impact have been measured. The target was prepared by evaporating a thin film of compound KI to a thick pure carbon substrate. The effects of multiple scattering of electrons penetrating the target films, electrons reflected from the thick pure carbon substrates and bremsstrahlung photons produced when incident electrons impacted on the targets were corrected by using the Monte Carlo method. For K K-shell and I L-shell X-ray characteristic peaks, the spectra were fitted using the spectrum-fitting program ALLFIT to extract the Kα and Kβ peak counts more accurately for element K, and Lα peak counts for element I. The experimental results were compared with some theoretical results developed recently and available experimental data from the literature. The experimental data for I L-shell X-ray production cross sections by 10–30 keV electron impact are given here for the first time.

X-RAY PRODUCTION, INNER SHELL IONIZATION AND READING’S THEOREM IN ION · ATOM COLLISIONS

1992 ◽  
Vol 02 (03) ◽  
pp. 197-209
Author(s):  
KEIZO ISHII
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Production Cross ◽  
X Rays ◽  
Ionization Cross ◽  
Heavy Charged Particles ◽  
X Ray ◽  
Inner Shell Ionization ◽  
Ionization Cross Sections ◽  
Shell Ionization

When a solid or gaseous target is bombarded with heavy charged particles, inner shell electrons of target atoms are ionized and characteristic x rays are produced. We can easily observe these x rays with a Si(Li) detector and derive inner-shell ionization cross section from the x-ray production cross sections. In this paper, we make a review of x-ray production, inner shell ionization and Reading’s theorem in light ion·atom collisions. This theorem is one of the most important ones in the ion·atom collision physics and permits precise discussion on comparison between experimental inner-shell ionization cross sections obtained with a Si(Li) detector and the calculations based on usual theories where the incident particle is assumed to interact with only one electron in an atom and the presence of other electrons is ignored.

LIGHT ION-INDUCED L-SHELL IONIZATION OF HIGH-Z ELEMENTS

1996 ◽  
Vol 06 (01n02) ◽  
pp. 39-50 ◽  
Author(s):  
E. PERILLO ◽  
P. CUZZOCREA ◽  
N. DE CESARE ◽  
G. SPADACCINI ◽  
M. VIGILANTE
Keyword(s):  
Cross Sections ◽  
Production Cross ◽  
Wave Functions ◽  
Ionization Cross ◽  
X Ray ◽  
Li Ion ◽  
Ion Impact ◽  
Ionization Cross Sections ◽  
Coupled Channel ◽  
Shell Ionization

L-shell X-ray production cross sections for selected heavy elements (Tl, Pb, Bi), of interest in BIO-PIXE analyses, have been measured by proton and 7 Li ion impact in the energy range 0.8–2.6 MeV and 1.8–3.3 MeV respectively. Further, production cross sections for 7 Li ion impact on Au between 1.0 and 2.4 MeV have been measured. L-subshell ionization cross sections have been extracted and arranged, together with similar results from other laboratories, in an analysis aiming at testing the performance of various theoretical approximations in the description of the ionization process. The disagreement observed at low values of the reduced velocity parameter ξ R L between the data and the predictions of the ECPSSR model is significantly reduced by using a United Atom approximation in the treatment of the binding correction, suggested by our group (ECPSSR-UA). The remaining discrepancies, mostly for the L 1-subshell, are almost completely removed by replacing the screened hydrogenlike wave functions with the more realistic Dirac-Hartree-Slater ones. In the case of 7 Li ions, especially for L 2-subshell, also a more refined Coulomb deflection correction and more sophisticated coupled channel calculations are needed.

Calculation and measurement of electron ionization cross sections for L and M shells

1992 ◽  
Vol 50 (2) ◽  
pp. 1642-1643
Author(s):  
Suichu Luo ◽  
David C. Joy ◽  
John R. Dunlap ◽  
Xinlei Wang
Keyword(s):  
Cross Sections ◽  
Correlation Energy ◽  
Calculation Algorithm ◽  
Ionization Cross ◽  
X Ray ◽  
Primary Mechanism ◽  
Consistent Field ◽  
Self Consistent Field ◽  
Ionization Cross Sections ◽  
Shell Ionization

The ionization of atoms by electrons is a process of great importance in physics, because it is the primary mechanism for energy loss of electron in matter and for X-ray microanalysis. Powell has critically compared various theoretical, semi- or empirical formulations with experiments and it is clear that although calculations and measurements have been carried out previously for K and to a lesser extent for L shells, very little data, both experimental and theoretical, exist for M shells.We have calculated K ,L (L1 and L23 ) and M( M1 ,M23 M45 )shell ionization cross section covering the entire periodic table and spanning the energy range from the critical ionization energy for a particular element up to 100 keV using Hartree-Slater central self- consistent field model. The calculation algorithm is essentially that described in Ref.3 but both exchange and correlation energy effects have been included in the computations to ensure that the computed cross-sections are valid at low overvoltage ratios, and relativistic corrections have also been included for accuracy at high incident energies.

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