Coulomb three-body effects in electron-impact ionization of argon

Rouvellou, B.; Rioual, Stéphane; Röder, J; Pochat, A.; Rasch, J.; Whelan, Colm T.; Walters, H. R. J.; Allan, R. J.

doi:10.1103/physreva.57.3621

Cited by 23 publications

(30 citation statements)

References 18 publications

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“…Here the agreement between theoretical predictions and experiment is found to be generally good concerning the relative shape, i.e., the angular dependence, of the cross sections, see e.g., Refs. [16][17][18]21,22]. One of the well-known outstanding issues in experiment, however, is the general lack of absolute cross-section data for ionization of the heavier targets.…”

Section: Introductionmentioning

confidence: 99%

Benchmark experiment for electron-impact ionization of argon: Absolute triple-differential cross sections via three-dimensional electron emission images

et al. 2011

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Single ionization of argon by 195-eV electron impact is studied in an experiment, where the absolute tripledifferential cross sections are presented as three-dimensional electron emission images for a series of kinematic conditions. Thereby a comprehensive set of experimental data for electron-impact ionization of a many-electron system is produced to provide a benchmark for comparison with theoretical predictions. Theoretical models using a hybrid first-order and second-order distorted-wave Born plus R-matrix approach are employed to compare their predictions with the experimental data. While the relative shape of the calculated cross section is generally in reasonable agreement with experiment, the magnitude appears to be the most significant problem with the theoretical treatment for the conditions studied in the present work. This suggests that the most significant challenge in the further development of theory for this process may lie in the reproduction of the absolute scale rather than the angular dependence of the cross section.

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Section: Introductionmentioning

confidence: 99%

Benchmark experiment for electron-impact ionization of argon: Absolute triple-differential cross sections via three-dimensional electron emission images

et al. 2011

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“…On the other hand, puzzling discrepancies remain in particular outside the scattering plane [9,19]. For low-energy electron impact ionization, significant differences between experiment and theoretical predictions were observed even inside the scattering plane [20,21]. Outside the scattering plane, only a few experiments for low-energy electron collisions with heavier targets were carried out for equal energy sharing conditions and both finalstate electrons being emitted perpendicular to the incident beam [22][23][24].…”

Section: Introductionmentioning

confidence: 99%

Low-energy electron-impact ionization of argon: Three-dimensional cross section

et al. 2012

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Low-energy (E 0 = 70.8 eV) electron impact single ionization of a 3p electron in argon has been studied experimentally and theoretically. Our measurements are performed using the socalled Reaction Microscope technique, which can cover nearly a full 4π solid angle for the emission of a secondary electron with energy below 15 eV and projectile scattering angles ranging from −8° to −30°. The measured cross sections are inter-normalized across all scattering angles and ejected energies. Several theoretical models were employed to predict the triple-differential cross sections. They include a standard distorted-wave Born approximation (DWBA), a modified version to account for the effects of post-collision interaction (DWBA-PCI), a hybrid second-order distortedwave plus R-matrix (DWB2-RM) method, and the recently developed B-spline R-matrix with pseudo-states (BSR) approach. The relative angular dependence of the BSR cross sections is generally found to be in reasonable agreement with experiment, and the importance of the PCI effect is clearly visible in this low-energy electron impact ionization process. However, there remain significant differences in the magnitude of the calculated and the measured TDCSs.

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“…An even more severe test of theory is presented by the symmetric collisions in which both final state electrons have the same energy and are observed at the same scattering angles on opposite sides of the beam direction in the scattering plane. Measurements of this type have been made on the 2s and 2p shells of neon (Rioual et al 1995(Rioual et al , 1997 and the 3p shell of argon (Bell et al 1995, Rouvellou et al 1998. DWBA calculations including initial channel polarization and PCI using the Gamov factor were performed for neon and argon (Rioual et al 1997, Rouvellou et al 1998.…”

Section: Introductionmentioning

confidence: 99%

“…The DWBA calculations reported by Rioual et al (1997) and Rouvellou et al (1998) for lowenergy symmetric ionization of the 3p shell of argon used the FM local approximation for PTX which was thought to be adequate. However, the validity of the FM approximation for the PTX has been challenged by Winkler et al (1999) who used projectile wavefunctions calculated by the full HF method.…”

Section: Introductionmentioning

confidence: 99%

Exchange effects in low energy electron impact ionization of the inner and outer shells of argon

Biava

Saha

Engel

et al. 2002

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

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First order distorted wave Born approximation (DWBA) triple differential cross sections are reported for low-energy electron-impact ionization of the inner 3s and outer 3p shells of argon. Previous DWBA works have demonstrated that experiment and theory are not in accord for low energy ionization of inert gases and here we investigate the importance of exchange scattering. Different approximations for treating exchange scattering are investigated. It is shown that exchange scattering is particularly important for 3s ionization. Even with a proper treatment of exchange, the first order calculations are still not in satisfactory agreement with experiment. Consequently higher order effects will have to be included to achieve a satisfactory description of the low-energy ionization process. We also investigated both the Hartree-Fock and optimized potential methods for calculating atomic wavefunctions and static potentials and found that both methods produced almost the same cross sections.

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Coulomb three-body effects in electron-impact ionization of argon

Cited by 23 publications

References 18 publications

Benchmark experiment for electron-impact ionization of argon: Absolute triple-differential cross sections via three-dimensional electron emission images

Benchmark experiment for electron-impact ionization of argon: Absolute triple-differential cross sections via three-dimensional electron emission images

Low-energy electron-impact ionization of argon: Three-dimensional cross section

Exchange effects in low energy electron impact ionization of the inner and outer shells of argon

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