scholarly journals Excitation of the lowest autoionizing level of caesium atoms by positron impact

2021 ◽  
Vol 2 (1) ◽  
pp. 77-83
Author(s):  
A. W. Munywoki ◽  
J. Okumu ◽  
C. S Singh
Keyword(s):  
Electron Impact ◽  
Cross Sections ◽  
High Energy ◽  
Impact Excitation ◽  
Electron Impact Excitation ◽  
Distorted Wave ◽  
Positron Impact ◽  
Intermediate Energies ◽  
Threshold Energies ◽  
Determining Factor

We have obtained differential and integral cross sections for the excitation of caesium atom to the lowest autoionizing level by positron impact using the distorted wave approximation. We have also done calculations for electron impact excitation of the same level using the same method and compared our present positron/electron impact results with the available theoretical positron/ electron impact results and experimental electron impact results. It is found that the present positron impact integral cross sections are higher than the cross sections of Pangantiwar and Srivastava at low and intermediate energies, but the results converge as the energy increases in the high energy range. The disagreement at near threshold energies is due to the different distortion potentials used in the two calculations. The charge on the projectile is also a determining factor in the shape of the scattering cross section curves.

Excitation of the 3D states of helium by electrons and positrons

1996 ◽  
Vol 74 (7-8) ◽  
pp. 509-517 ◽  
Author(s):  
Surbhi Verma ◽  
Rajesh Srivastava
Keyword(s):  
Electron Impact ◽  
Cross Sections ◽  
Ground State ◽  
Stokes Parameters ◽  
Impact Excitation ◽  
Electron Impact Excitation ◽  
Distorted Wave ◽  
Positron Impact ◽  
Wave Approximation ◽  
Electrons And Positrons

Distorted-wave approximation calculations were carried out for the electron-impact excitation of 31,3D states from the 11S ground state of helium. Results are presented at an electron energy of 40 eV for the Stokes parameters P1-P4; coherence parameters Pl, γ, [Formula: see text], ρ00; and differential cross sections where most other theoretical and experimental data are available for comparison. The calculation is further extended to the positron-impact 11S–31D excitation in helium and comparison with the corresponding electron-impact results is discussed.

Relativistic Distorted-Wave Calculations of Electron Impact Excitation Cross Sections of Be-Like C 2+ Ions

2007 ◽  
Vol 24 (3) ◽  
pp. 691-694 ◽  
Author(s):  
Jiang Jun ◽  
Dong Chen-Zhong ◽  
Xie Lu-You ◽  
Wang Jian-Guo ◽  
Yan Jun ◽  
...  
Keyword(s):  
Electron Impact ◽  
Cross Sections ◽  
Impact Excitation ◽  
Electron Impact Excitation ◽  
Distorted Wave ◽  
Excitation Cross Sections

scholarly journals Electron Impact Excitation of Extreme Ultra-Violet Transitions in Xe7+ – Xe10+ Ions

Atoms ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 76
Author(s):  
Aloka Kumar Sahoo ◽  
Lalita Sharma
Keyword(s):  
Electron Impact ◽  
Electron Energy ◽  
Cross Sections ◽  
Energy Levels ◽  
Ultra Violet ◽  
High Energy ◽  
Impact Excitation ◽  
Rate Coefficients ◽  
Electron Impact Excitation ◽  
Excitation Threshold

In the present work, a detailed study on the electron impact excitation of Xe7+, Xe8+, Xe9+ and Xe10+ ions for the dipole allowed (E1) transitions in the EUV range of 8–19 nm is presented. The multi-configuration Dirac–Fock method is used for the atomic structure calculation including the Breit and QED corrections along with the relativistic configuration interaction approach. We have compared our calculated energy levels, wavelengths and transition rates with other reported experimental and theoretical results. Further, the relativistic distorted wave method is used to calculate the cross sections from the excitation threshold to 3000 eV electron energy. For plasma physics applications, we have reported the fitting parameters of these cross sections using two different formulae for low and high energy ranges. The rate coefficients are also obtained using our calculated cross sections and considering the Maxwellian electron energy distribution function in the electron temperature range from 5 eV to 100 eV.

scholarly journals The effect of exchange and absorption potential in the distorted wave calculation of electron impact excitation of the autoionizing state of caesium

2020 ◽  
Vol 1 (1) ◽  
pp. 39-46
Author(s):  
A. A. Ochieng ◽  
J Okumu ◽  
C S Singh
Keyword(s):  
Energy Range ◽  
Electron Impact ◽  
Cross Sections ◽  
Intermediate Energy ◽  
Impact Excitation ◽  
Experimental Result ◽  
Electron Impact Excitation ◽  
Distorted Wave ◽  
Autoionizing State ◽  
Absorption Potential

We have calculated the differential and integral cross sections for electron impact excitation of the lowest autoionizing level of caesium atoms in the energy range 13 – 500 eV using the distorted wave method. In this study we have used a complex distortion potential as the distortion potential both at the initial and the final channels. Our results are compared amongst themselves to establish the effect of exchange and imaginary absorption potentials. We also compared with other available theoretical and experimental results to determine the suitability of our present method. From the results it is seen that when an absorption potential is included in the distortion potential, the integral cross section moves closer to the experimental result in the intermediate energy range 19 – 40 eV.

Vacuum Ultraviolet Excitation of H(2p) by Electron Impact on H2

1972 ◽  
Vol 50 (18) ◽  
pp. 2211-2216 ◽  
Author(s):  
J. W. McConkey ◽  
F. G. Donaldson
Keyword(s):  
Electron Impact ◽  
Cross Sections ◽  
Vacuum Ultraviolet ◽  
High Energy ◽  
Impact Excitation ◽  
Electron Impact Excitation ◽  
Ultraviolet Excitation ◽  
A Value ◽  
High Energy Behavior ◽  
Energy Behavior

'Polarization-free' measurements are presented of the electron impact excitation of Lyman α by electron impact on H2 in the energy range 20–2000 eV. Cross sections are made absolute by normalizing to the data of Mumma and Zipf at 100 eV. A broad maximum in the function occurs around 60 eV, some 20 eV lower than was found by some previous workers. Reasons for this discrepancy are discussed. The high energy behavior of the cross section is analyzed in terms of the Bethe approximation and a value of 0.11 is obtained for the square of the dipole matrix element of the transitions involved.

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