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.

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.

Relativistic distorted-wave calculation of electron impact excitation of silver and gold

1996 ◽  
Vol 74 (11-12) ◽  
pp. 889-896 ◽  
Author(s):  
V. Zeman ◽  
R. P. McEachran ◽  
A. D. Stauffer
Keyword(s):  
Electron Impact ◽  
Cross Sections ◽  
Dominant Role ◽  
Incident Electron ◽  
Stokes Parameters ◽  
Impact Excitation ◽  
Electron Impact Excitation ◽  
Distorted Wave ◽  
Wave Calculation ◽  
Mott Scattering

Relativistic distorted-wave calculations were performed for the electron impact excitation of silver and gold to their first (np) 2P1/2,3/3 levels at incident electron energies of 30–100 eV. Results are reported for the differential and integrated cross sections, differential and integrated Stokes parameters, and generalized STU parameters. Mott scattering is found to play an increasingly dominant role at larger energies and scattering angles.

Electron-impact excitation of Li II in the distorted-wave approximation

1980 ◽  
Vol 22 (1) ◽  
pp. 132-137 ◽  
Author(s):  
Michael S. Pindzola ◽  
A. K. Bhatia ◽  
A. Temkin
Keyword(s):  
Electron Impact ◽  
Impact Excitation ◽  
Electron Impact Excitation ◽  
Distorted Wave ◽  
Wave Approximation
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