scholarly journals Binary-Encounter Model for Direct Ionization of Molecules by Positron-Impact

Atoms ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 99
Author(s):  
Małgorzata Franz ◽  
Katarzyna Wiciak-Pawłowska ◽  
Jan Franz
Keyword(s):  
Cross Sections ◽  
Positron Impact ◽  
Standard Quantum ◽  
Direct Ionization ◽  
Wide Range ◽  
Small Set ◽  
The Cross ◽  
Ionization Cross Sections ◽  
Binary Encounter ◽  
Good Agreement

We introduce two models for the computation of direct ionization cross sections by positron impact over a wide range of collision energies. The models are based on the binary-encounter-Bethe model and take into account an extension of the Wannier theory. The cross sections computed with these models show good agreement with experimental data. The extensions improve the agreement between theory and experiment for collision energies between the first ionization threshold and the peak of the cross section. The models are based on a small set of parameters, which can be computed with standard quantum chemistry program packages.

K-, L-, and M-shell ionization of atoms by electron and positron impact

1996 ◽  
Vol 74 (7-8) ◽  
pp. 376-383 ◽  
Author(s):  
S. P. Khare ◽  
J. M. Wadehra
Keyword(s):  
Experimental Data ◽  
Cross Sections ◽  
Positron Impact ◽  
Electrons And Positrons ◽  
Virtual Photons ◽  
Plane Wave Born Approximation ◽  
Ionization Cross Sections ◽  
Impact Energies ◽  
Shell Ionization ◽  
Good Agreement

The plane-wave Born approximation with Coulomb, relativistic, and exchange corrections is employed to obtain the K-, L1-, L2-, L3-, and M-shell ionization cross sections of a number of atoms bombarded by electrons and positrons in the energy range varying from the threshold of ionization to 1 GeV. Transverse interaction of virtual photons with atoms is also included and it is found to be of great significance for impact energies greater than about 1 MeV. For K- and L-shell ionization, good agreement between the theoretical values and various experimental data for electron-impact cross sections is obtained. However, for the M shell, the theory overestimates the experimental cross sections. For positron impact the agreement between the present results and the limited experimental data is found to be quite satisfactory.

Single ionization by positron impact

1996 ◽  
Vol 74 (7-8) ◽  
pp. 367-372 ◽  
Author(s):  
J. Moxom ◽  
P. Ashley ◽  
G. Laricchia
Keyword(s):  
Energy Range ◽  
Cross Sections ◽  
Positron Impact ◽  
Ionization Cross ◽  
Positron Scattering ◽  
Direct Ionization ◽  
Low Energies ◽  
Ionization Cross Sections ◽  
Impact Energies ◽  
Existing Data

The single direct ionization cross sections for positron scattering [Formula: see text] on He, Ar, Kr, and H2 were measured and compared with existing data and the corresponding cross sections for electron impact [Formula: see text]. At most impact energies the present data for He and H2 are in reasonable accord with other measurements and, in the case of He, with some of the available calculations. At low energies, [Formula: see text] is found to increase more slowly than [Formula: see text], probably due to the importance of Ps formation in this energy range.

scholarly journals Cross sections of electron collisions with noble gases atoms

2021 ◽  
pp. 11-16
Author(s):  
Rusudan Golyatina ◽  
Sergei Maiorov
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Noble Gas ◽  
Empirical Formulas ◽  
Electron Collisions ◽  
Wide Range ◽  
Analytical Formulas ◽  
The Cross ◽  
Approximation Coefficients ◽  
Ionization Cross Sections

Consideration is given to the analysis of data on the cross sections of elastic and inelastic col-lisions of electrons with noble gas atoms. The transport (diffusion) cross section, the excita-tion and ionization cross sections are studied. For the selected sets of experimental and theo-retical data, optimal analytical formulas are found and approximation coefficients are select-ed for them. The obtained semi-empirical formulas allow us to reproduce the cross section values in a wide range of collision energies from 0.001 to 10000 eV with an accuracy of sev-eral percent.

scholarly journals Direct Ionization Cross Sections of Uranium Atom By Electron Impact

2021 ◽  
Vol 16 (2) ◽  
Author(s):  
Shivani Gupta ◽  
Piyush Sinha
Keyword(s):  
Electron Impact ◽  
Cross Sections ◽  
Impact Ionization ◽  
Uranium Atom ◽  
Electron Impact Ionization ◽  
Ionization Cross ◽  
Direct Ionization ◽  
Wide Range ◽  
Ionization Cross Sections ◽  
Theoretical Results

A theoretical model for electron impact ionization cross section has been found to be reliable for wide range of atoms is applied in this paper to the Uranium atom. A modified Kim binary encounter Bethe (BEB) method and modified Khare BEB method is employed for calculating electron impact ionization cross sections. The present results so obtained are compared with experimental as well as theoretical results known to the best of our knowledge.

TOTAL CROSS SECTIONS FOR IONIZATION BY ELECTRON IMPACT

1966 ◽  
Vol 44 (16) ◽  
pp. 1967-1973 ◽  
Author(s):  
A. G. Harrison ◽  
E. G. Jones ◽  
S. K. Gupta ◽  
G. P. Nagy
Keyword(s):  
Electron Impact ◽  
Cross Sections ◽  
Linear Correlation ◽  
Molecular Polarizability ◽  
Ionization Cross ◽  
Total Cross Sections ◽  
Atomic Ionization ◽  
Wide Range ◽  
The Cross ◽  
Ionization Cross Sections

Total cross sections for ionization by 75 V electrons have been measured for a wide range of molecules. On the whole the results are in agreement with the cross sections reported by Lampe etal. rather than those reported by Otvos and Stevenson. The results fit neither a single linear correlation with molecular polarizability nor a simple postulate of additivity of atomic ionization cross sections.

scholarly journals Analytical approximation of cross sections of collisions of electrons with atoms of inert gases

2021 ◽  
Vol 9 (4) ◽  
pp. 298-309
Author(s):  
Rusudan Golyatina ◽  
Sergei Maiorov
Keyword(s):  
Cross Sections ◽  
Noble Gas ◽  
Theoretical Data ◽  
Analytical Approximation ◽  
Inert Gases ◽  
Empirical Formulas ◽  
Wide Range ◽  
The Cross ◽  
Approximation Coefficients ◽  
Ionization Cross Sections

The paper presents an analysis of data on the cross sections of elastic and inelastic collisions of electrons with noble gas atoms. The transport (diffusion) cross sec-tion, the excitation and ionization cross sections are considered. For the selected sets of experimental and theoretical data, optimal analytical formulas are found and approximation coefficients are selected for them. The obtained semi-empirical formulas allow us to reproduce the cross section values in a wide range of colli-sion energies from 0.001 to 10000 eV with an accuracy of several percent.

scholarly journals Electron-impact double ionization of the carbon atom

2018 ◽  
Vol 620 ◽  
pp. A188 ◽  
Author(s):  
Valdas Jonauskas
Keyword(s):  
Carbon Atom ◽  
Electron Impact ◽  
Cross Sections ◽  
Double Ionization ◽  
Impact Excitation ◽  
Rate Coefficients ◽  
Electron Impact Excitation ◽  
Ionization Cross ◽  
Ionization Cross Sections ◽  
Good Agreement

Electron-impact single- and double-ionization cross sections and Maxwellian rate coefficients are presented for the carbon atom. Scaling factors are introduced for the electron-impact excitation and ionization cross sections obtained in the distorted wave (DW) approximation. It is shown that the scaled DW cross sections provide good agreement with measurements for the single ionization of the C atom and C1+ ion. The direct double-ionization (DDI) process is studied using a multi-step approach. Ionization–ionization, excitation–ionization–ionization, and ionization–excitation–ionization branches are analyzed. It is demonstrated that the three-step processes contribute ≼40% of the total DDI cross sections for the case where one of the electrons takes all of the excess energy after the first ionization process.

scholarly journals The Electron Impact Ionization Cross Sections of Methanol, Ethanol and 1-Propanol

Atoms ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 60 ◽  
Author(s):  
Yogesh Kumar ◽  
Manoj Kumar ◽  
Sachin Kumar ◽  
Rajeev Kumar
Keyword(s):  
Electron Impact ◽  
Cross Sections ◽  
Impact Ionization ◽  
Experimental Results ◽  
Oscillator Strengths ◽  
Ionization Cross ◽  
Total Ionization ◽  
Plane Wave Born Approximation ◽  
Ionization Cross Sections ◽  
Good Agreement

In the present investigation, the plane-wave Born approximation was employed to calculate the total ionization cross sections by electron impact of methanol, ethanol and 1-propanol from the threshold of ionization to 10 MeV. This method requires continuum generalized oscillator strengths (CGOSs). The two different semi-phenomenological expressions of CGOS, given by Mayol and Salvat and Weizsacker and Williams, along with approximated form of the continuum optical oscillator strength (COOS) by Khare et al. were used. Furthermore, the average of the above two CGOSs was also used. The calculated ionization cross sections were compared to the available previous theoretical results and experimental data. Out of three CGOSs, the present results with the average CGOS were found in good agreement with the available experimental results for all the considered molecules. Collision parameters CRP were also calculated from 0.1 to 100 MeV and the calculations were found to be in excellent agreement with the experimental results of Reike and Prepejchal.

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