scholarly journals Total Ionisation Cross Sections in e??H(2S) Scattering

1989 ◽  
Vol 42 (5) ◽  
pp. 475 ◽  
Author(s):  
KK Mukherjee ◽  
Keka Basu Choudhury ◽  
N Ranjit Singh ◽  
PS Mazumdar ◽  
S Brajamani
Keyword(s):  
Cross Sections ◽  
Atomic Hydrogen ◽  
Wave Method ◽  
Distorted Wave ◽  
Total Cross Sections ◽  
Theoretical Predictions ◽  
Impact Ionisation ◽  
Distorted Wave Method ◽  
Final Channel ◽  
Experimental Findings

Total cross sections for the electron impact ionisation from the 2S state of atomic hydrogen have been calculated in the energy range 5 �1-68 eV of the incident electron by using a rigorous distorted wave method in which the effects of both the initial and final channel distortions are taken into account. The present results show improved agreement with experimental findings in comparison with other theoretical predictions.

scholarly journals Ground State Positronium Formation Cross Sections for Scattering of Positrons from Li

1991 ◽  
Vol 44 (5) ◽  
pp. 515 ◽  
Author(s):  
KK Mukherjee ◽  
N Ranjit Singh ◽  
Keka Basu Choudhury ◽  
PS Mazumdar ◽  
S Brajamani
Keyword(s):  
Energy Range ◽  
Cross Sections ◽  
Ground State ◽  
Positronium Formation ◽  
Distorted Wave ◽  
Total Cross Sections ◽  
Wave Approximation ◽  
Theoretical Predictions

Total cross sections for positronium formation in e+-Li scattering have been studied in the framework of the distorted wave approximation in the energy range 1-50 eV by taking consistent account of the effect of the target distortion. The results are compared with existing theoretical predictions.

The application of variational methods to atomic scattering problems II. Impact excitation of the 2s level of atomic hydrogen-distorted wave treatment

1952 ◽  
Vol 212 (1111) ◽  
pp. 521-530 ◽  
Keyword(s):  
Cross Section ◽  
Atomic Hydrogen ◽  
Plane Waves ◽  
Wave Functions ◽  
Impact Excitation ◽  
Wave Method ◽  
Distorted Wave ◽  
Scattering Problems ◽  
The Cross ◽  
Distorted Wave Method

The cross-section for excitation of the 2 S level of atomic hydrogen by electrons is calculated using the distorted wave method with full allowance for exchange. The distorted wave functions used in the calculations are determined by Hulthèn’s variational method. The initial wave functions, representing the motion of an electron in the field of a normal atom with allowance for exchange, are taken to be those calculated by Massey & Moiseiwitsch (1950). The final wave functions, representing the motion of an electron in the field of a hydrogen atom in the 2 S state, have been obtained by a modification of the same method. Exchange effects are found to be less important in determining the forms of these wave functions. The cross-sections obtained are considerably smaller than those calculated by the Born-Oppenheimer method, in which the electron wave functions are undistorted plane waves. This is largely because the symmetrical cross-section, which has the greater weight in determining the mean cross-section, is much greater than the antisymmetrical according to the Born-Oppenheimer method, but the reverse is true if distortion is allowed for. In no case does the distorted wave method give results exceeding the theoretical upper limit, whereas with plane waves this limit is exceeded at certain electron energies by the symmetrical cross-section.

The excitation of the 2 3 P state of helium by electron impact

1960 ◽  
Vol 258 (1293) ◽  
pp. 147-158 ◽  
Keyword(s):  
Electron Impact ◽  
Cross Sections ◽  
Ground State ◽  
Wave Method ◽  
Distorted Wave ◽  
Polarization Of Radiation ◽  
Oppenheimer Approximation ◽  
Distorted Wave Method

Cross-sections for excitation of the 2 3 P state of helium from the ground state have been calculated by the distorted-wave method. The polarization of radiation emitted as a result of the excitation is also calculated. Comparison is made with the corresponding results given by the Born—Oppenheimer approximation. Although there are considerable differences at electron energies below 100 eV these are much less marked than for the excitation of the 2 3 S state. The distorted wave method gives cross-sections in closer agreement with observation but substantial discrepancies still remain. It is difficult, however, to estimate their magnitude with any certainty because there are inconsistencies in the observed data.

The cross-section for ionization of O 5+ by electron impact

1963 ◽  
Vol 271 (1346) ◽  
pp. 379-386 ◽  
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Ionization Energy ◽  
Wave Method ◽  
Distorted Wave ◽  
Ionization Cross ◽  
The Cross ◽  
Ionization Cross Sections ◽  
Distorted Wave Method ◽  
Hydrogenic Ions

The calculation of ionization cross-sections is described. For O 5+ a Coulomb-Born-Oppenheimer method is used. Previous calculations for O 4+ with the distorted wave method are corrected and extended. The results are given in tables 1 to 4 and in figure 1. For O 4+ (ionization energy E i — 8·37 x 13·6 eV) the cross-section Q has its maximum at an energy of the incident electron E = 2·3 E i : Q max. = 2·74 x 10 -2 π a 2 0 = 2·42 x 10 -18 cm 2 . For O 5+ ( E i = 10·15 x 13·6 eV) the maximum is at E = 1·85 E i : Q max. = 0·97 x 10 -2 π a 2 0 = 0·86 x 10 -18 cm 2 . The corresponding reduced cross-sections Q red. = ( E i /13·6 eV ) 2 x Q /Kζπ a 2 0 ) are for O 4+ (ζ = 2): Q red. = 0·96, and for O 5+ (ζ = 1): Q red. = 1·00. The results are similar to those of Rudge & Burgess (1962) for hydrogenic ions.

Distorted wave calculation of the positronium formation in positron-sodium and positron-potassium scattering

1998 ◽  
Vol 08 (04) ◽  
pp. 217-224
Author(s):  
K. B. Choudhury ◽  
M. Bhattacharya ◽  
N. C. Deb ◽  
N. R. Singh ◽  
M. B. Singh ◽  
...  
Keyword(s):  
Cross Sections ◽  
Positronium Formation ◽  
Distorted Wave ◽  
Total Cross Sections ◽  
Wave Approximation ◽  
Experimental Findings ◽  
Wave Calculation

Total cross sections for the positronium formation in the ground ( n =1) and excited ( n =2) states in e+ - Na and e+ - K scattering have been studied within the framework of a distorted wave approximation. The present results have been compared with other theoretical and experimental findings.

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