Projectile interaction effects in out-of-plane excitation-ionization of helium

Harris, Allison; Esposito, Teresa

doi:10.1088/0953-4075/48/21/215201

Cited by 3 publications

(2 citation statements)

References 34 publications

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“…The two models we use here are the 4-Body Distorted Wave (4DW) and first Born approximation (FBA) models. The details of these calculations have been presented in [14], and we include only the relevant details here. The two main differences between the 4DW and FBA models are the treatment of the projectile and the inclusion of post-collision interaction (PCI).…”

Section: Theorymentioning

confidence: 99%

Angular momentum and orientation effects in excitation-ionization collisions

Harris¹,

Esposito²

2016

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

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We present theoretical fully differential cross sections (FDCS) for electron-impact excitation-ionization of helium in which the final state He+ ion is oriented in a particular direction. Specifically, we study the process for He+ ions in the 2p0 state. Using our 4-body distorted wave model, we show a strong dependence of the FDCS on the ion’s orientation and trace some unexpected structures in the FDCS to the L = 2 term in the partial wave expansion for the ionized electron. A comparison is drawn to the ionization of oriented Mg (3p0) atoms, and unlike that process, we find that for excitation-ionization angular momentum must be transferred from either the projectile or the target atom.

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Section: Theorymentioning

confidence: 99%

Angular momentum and orientation effects in excitation-ionization collisions

Harris¹,

Esposito²

2016

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

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“…In the case of orientation along the beam direction or along the momentum transfer direction, almost no forward ejection is observed, but a strong backward recoil peak is seen. This feature has previously been traced to the post-collision interaction between outgoing the electron and scattered projectile, as well as projectile-ion interactions [31]. For orientation perpendicular to the beam direction or perpendicular to the momentum transfer direction, a broader distribution of ejected electrons is observed, although the magnitude of the FDCS for these orientations are 5-10 times smaller than orientations along the beam or momentum transfer directions.…”

Section: A Fdcsmentioning

confidence: 86%

Anisotropy in excitation-ionization double-differential cross sections

Harris

Saxton

2018

Phys. Rev. A

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Simultaneous ionization and excitation of helium by electron impact is studied through ejected electron angle integrated double differential cross sections (DDCS) as a function of ionized electron energy using the 4-Body Distorted Wave model. Results are presented for different alignments of the 2p0 magnetic substate of the He + ion, and alignment effects observed in fully differential cross sections are shown to persist in the DDCS. Examination of the DDCS for different orientations leads to a determination of anisotropy parameters and phase angles between substate amplitudes as a function of ejected electron energy.

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A theoretical study on collision mechanisms for low energy electron impact ionization of helium in the perpendicular geometry

Yang¹,

Sui-Meng²,

Ling-Ling³

et al. 2017

Acta Phys. Sin.

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Under the condition of ten different incident energies ranging from 3 eV to 80 eV above the ionization potential of helium and the outgoing electrons having equal energies, by making use of 3C model and modified 3C model, the triple differential cross sections of electron-impact single ionization of the ground state of helium in the perpendicular geometry are calculated. The result is compared with corresponding experimental result to systematically investigate the influences of various screening effects on the triple differential cross sections for helium. The collision mechanisms of the triple differential cross sections are explored. The result shows that the effects of dynamic screening in the final state can directly affect the structures of the triple differential cross sections at lower incident energy, which will unavoidably affect the angular distribution and relative amplitude of side peaks at angles =90 and =270. The screening effects of residual electron in the final state of He+ have a similar significant effect on the amplitude of triple differential cross section of helium and angular distributions and relative amplitudes of side peaks at angles =90 and =270. When the incident energy is over 84.6 eV, the screening effect of residual electron in the final state of He+ has a slight effect on the amplitude of triple differential cross section, which can be overlooked. But the effects of dynamic screening in the final state on side peaks at angles =90 and =270 need considering. In addition, by taking advantage of DS3C-Z model, the results of collision mechanism of various peaks at angles =180, =90 and =270 show that the middle peak at angle =180 is produced by a process called triple scattering mechanism and then the side peaks at angles =90 and =270 are produced by a process called double scattering mechanism. Such a collision mechanism has a direct influence on the generation and variation law of triple differential cross sections.

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Projectile interaction effects in out-of-plane excitation-ionization of helium

Cited by 3 publications

References 34 publications

Angular momentum and orientation effects in excitation-ionization collisions

Angular momentum and orientation effects in excitation-ionization collisions

Anisotropy in excitation-ionization double-differential cross sections

A theoretical study on collision mechanisms for low energy electron impact ionization of helium in the perpendicular geometry

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