Convergent calculations for simultaneous electron-impact ionization-excitation of helium

Kheifets, Anatoli; Bray, Igor; Bartschat, Klaus

doi:10.1088/0953-4075/32/15/104

Cited by 34 publications

(39 citation statements)

References 18 publications

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“…Dupré et al [21] reported their ionization-excitation measurement at E 0 Ӎ 5.5 keV and E 2 = 5 , 10, and 75 eV. The first Born results for the two lowest electron energies of 5 and 10 eV are well below the experiment and only for the 75 eV case is agreement with experiment satisfactory [3,4]. The second Born calculations [5,6] are somewhat closer to experiment but significant discrepancies still exist for the two lowest ejected electron energies.…”

Section: A Ionization With Excitationmentioning

confidence: 85%

“…The first Born term has been investigated in great detail and the benchmark results had been established for the electron-impact ionization excitation of He to the n = 2 state [3,4]. There is also a good agreement between different close-coupling theories for the second Born contribution as far as ionization excitation is concerned [5,6].…”

Section: Introductionmentioning

confidence: 98%

“…In our earlier work, we applied the CCC formalism to electron impact ionization with excitation and double ionization [the so-called ͑e ,3e͒ reaction] in the first Born regime. The model was used to describe the twoelectron ionization at a very large projectile energy of 5.5 keV [3,15]. In subsequent ͑e ,3e͒ experiments, the energy of the projectile was lowered to 2 keV [16,17] and some deviations from the first Born regime became obvious.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Second-order Born model for two-electron atomic ionization by fast charged-particle impact

Kheifets

2004

Phys. Rev. A

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We develop a theoretical model to describe simultaneous ionization excitation and double ionization of a two-electron atomic shell (i.e., He 1s 2 ) by a fast charged-particle impact. The model accounts for the projectile-target interaction to the second order whereas the interaction of the two target electrons ejected into continuum is treated nonperturbatively by the convergent close-coupling (CCC) method. In the second-order term, all intermediate states of the target between two subsequent interactions with the projectile are weighted equally with an average energy denominator (the so-called closure approximation) and only the dipole interaction of the projectile with the target is included. The model is suited to describe two-electron ionization processes with large projectile velocity, small momentum transfer, and small to intermediate energy of the ejected electrons. The model is applied to ionization excitation and double ionization of He by electron and positron impact in kinematics of recent experiments.

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Section: A Ionization With Excitationmentioning

confidence: 85%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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Second-order Born model for two-electron atomic ionization by fast charged-particle impact

Kheifets

2004

Phys. Rev. A

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“…As shown by Kheifets et al [40] for the more complicated simultaneous ionization-excitation process, such expansions make it possible to get effectively converged results for the scattering of the slow ejected electron from the residual He + ion, while still treating the projectile-target interaction perturbatively.…”

Section: Distorted-wave Modelsmentioning

confidence: 99%

Single ionization of helium by 102 eV electron impact: three-dimensional images for electron emission

Dürr

Dimopoulou

Dorn

et al. 2006

J. Phys. B: At. Mol. Opt. Phys.

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Single ionization of helium by 102 eV electron impact has been studied by measuring the momentum vectors of all final-state particles, i.e., two electrons and the He + ion, with an advanced reaction microscope. Fully differential cross sections for asymmetric scattering geometry, which have been normalized to an absolute scale, have been obtained covering a large range of emission angles for the emitted low-energy (E 15 eV) electron and different scattering angles for the fast electron. Strong electron emission out of the projectile scattering plane is confirmed for electron impact, as was observed before for heavy-ion impact ionization. The data are compared with theoretical predictions from a three-Coulomb wavefunction model, first-order and second-order distortedwave approaches, as well as a convergent close-coupling calculation.

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“…Even for the coplanar geometry, significant discrepancies between theory and experiment can occur under such conditions, if the part of the projectile-target interaction responsible for ionization is accounted for only to first order [12]. Such experiments were performed by Dupré et al [13] and later by Avaldi et al [14] and Rouvellou et al [15].…”

mentioning

confidence: 99%

Electron-Impact Ionization and Excitation of Helium to then=1–4Ionic States

2006

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We present high-precision (e,2e) measurements and calculations for the e-He four-body Coulomb breakup problem. Cross-section ratios for ionization and excitation of the first three excited states of He+ relative to the ground state have been measured for incident energies between 112 and 319 eV. Comparing the data with predictions from a state-of-the-art hybrid distorted-wave+convergent R matrix with pseudostates (close coupling) approach shows that treating the projectile-target interaction at least to second order is crucial to obtain reasonable agreement between theory and experiment. Nevertheless, our benchmark studies reveal significant theoretical problems for the symmetric energy-sharing cases, thus indicating the need for further improvement.

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Convergent calculations for simultaneous electron-impact ionization-excitation of helium

Cited by 34 publications

References 18 publications

Second-order Born model for two-electron atomic ionization by fast charged-particle impact

Second-order Born model for two-electron atomic ionization by fast charged-particle impact

Single ionization of helium by 102 eV electron impact: three-dimensional images for electron emission

Electron-Impact Ionization and Excitation of Helium to then=1–4Ionic States

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