scholarly journals Ionisationsquerschnitt von OV gegenüber Elektronenstoß unter teilweiser Berücksichtigung des Austauschs

1961 ◽  
Vol 16 (6) ◽  
pp. 583-598 ◽  
Author(s):  
F. B. Malik ◽  
E. Trefftz
Keyword(s):  
Angular Momentum ◽  
Kinetic Energy ◽  
Cross Section ◽  
Ionization Energy ◽  
Total Angular Momentum ◽  
Ionization Cross Section ◽  
Wave Method ◽  
Distorted Wave ◽  
Ionization Cross ◽  
Distorted Wave Method

The ionization cross-section of highly ionized oxygen, O4+, is calculated according to the “distorted-wave” method. Exchange between the scattered and the ejected electron is taken into account as far as it is of long range nature. It is shown that contributions of high total angular momentum L are essential, L=0 giving only 3% of the total cross-section. This result should qualitatively be the same for all highly ionized atoms, whereas the following seems to be a special feature of O V ionization: for energies around twice the ionization energy the contributions of the optically allowed transitions of the ejected electron (angular momentum lej=1) are relatively small. The contributions of lej =0, 1, 2 and 3 are about 16%, 18%, 24% and 19% respectively for E=20.13.6 eV=2.39 × Ionization energy. The maximum cross section is 0.112 at. u. = 0.31 ·10-18 cm2 for electrons of 310 eV kinetic energy (2.8 × ionization energy). It is about twice as large as given by the ELWERT formula.

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.

The triple differential cross section for the ionization of hydrogen atoms under electron impact

1984 ◽  
Vol 62 (10) ◽  
pp. 968-972 ◽  
Author(s):  
A. S. Ghosh ◽  
P. S. Mazumdar ◽  
Madhumita Basu
Keyword(s):  
Differential Cross Section ◽  
Cross Section ◽  
Reasonable Agreement ◽  
Ionization Cross Section ◽  
Orbital Method ◽  
Distorted Wave ◽  
Hydrogen Atoms ◽  
Ionization Cross ◽  
Triple Differential Cross Section ◽  
Theoretical Predictions

The triple differential ionization cross section (TDCS) in electron–hydrogen scattering has been calculated using a distorted wave polarized orbital method. The present TDCS results at 100 and 113.6 eV are in reasonable agreement with the measured values of Weigold et al. and the theoretical predictions of Smith. Winters, and Bransden.

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.

scholarly journals The convergence of electron collisional ionization cross-section computations for atoms and ions in distorted-wave approximation

2018 ◽  
pp. 1-24
Author(s):  
Boris Nikolaevich Chetverushkin ◽  
Vladimir Anontol’evich Gasilov ◽  
Mikhail Evgenievich Zhukovsky ◽  
Vasily Sergeevich Zakharov ◽  
Mikhail Borisovich Markov
Keyword(s):  
Cross Section ◽  
Ionization Cross Section ◽  
Distorted Wave ◽  
Ionization Cross ◽  
Wave Approximation ◽  
Collisional Ionization

scholarly journals Distortion of the Ionization Cross Section of He by the Coherence Properties of a C6+ Beam

Atoms ◽  
2019 ◽  
Vol 7 (1) ◽  
pp. 31 ◽  
Author(s):  
Francisco Navarrete ◽  
Raúl Barrachina ◽  
Marcelo Ciappina
Keyword(s):  
Cross Section ◽  
Born Approximation ◽  
Qualitative Agreement ◽  
Ionization Cross Section ◽  
Distorted Wave ◽  
Initial State ◽  
Ionization Cross ◽  
Final State ◽  
Refined Method ◽  
Rigorous Procedure

We analyze the influence of the coherence of the projectile’s beam in scattering phenomena. We focus our study in the ionization of He by C 6 + projectiles at 100 MeV/amu. We assess the influence of this effect by performing a Born initial state and continuum distorted wave final state (CDW-B1) calculation together with a rigorous procedure to account for the initial coherence properties of the projectile’s beam. These calculations, which had been previously performed for only the scattering and perpendicular collision planes and within the First Born approximation (FBA), were repeated for an ampler set of collision planes. Additionally, a more refined method to describe the applicability of the aforementioned procedure, is used. We achieve a better qualitative agreement with the experimental results.

Positron-impact ionization of hydrogen atoms

1985 ◽  
Vol 63 (5) ◽  
pp. 621-624 ◽  
Author(s):  
A. S. Ghosh ◽  
P. S. Majumdar ◽  
Madhumita Basu
Keyword(s):  
Cross Section ◽  
Ionization Cross Section ◽  
Impact Ionization ◽  
Orbital Method ◽  
Distorted Wave ◽  
Positron Impact ◽  
Hydrogen Atoms ◽  
Ionization Cross ◽  
Channel Wave ◽  
Final Channel

The ionization cross section of hydrogen atoms by positron impact has been calculated by using a distorted-wave polarized-orbital method. We have employed two models depending on the choice of the final-channel wave function, and the two sets of results differ dramatically. We have also found that below 100 eV the total positron-impact ionization cross section including positronium formation is appreciably larger than the corresponding results for electron-impact ionization.

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