Hartree-Fock treatment of exchange in (e,2e) collisions

Winkler, Kathrin; Madison, Don H.; Saha, H. P.

doi:10.1088/0953-4075/32/19/303

Cited by 23 publications

(31 citation statements)

References 28 publications

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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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Section: Introductionmentioning

confidence: 99%

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

et al. 2012

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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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“…It is no good simply ignoring it, for if we take Q͑͒ = 0, Eq. ͑36͒ admits only real solutions, regardless of the strength of the inelastic processes ͑as measured by ␥͒ or the value of p. Thus none of the oscillatory patterns of decay known to characterize this problem ͓e.g., in the Franck-Hertz experiment ͑Robson et al., 2000;Sigeneger et al, 2003͔͒ can be reproduced with such a drastic assumption. Likewise, neglecting heat flux in even the simple case of elastic collisions governed by a constant collision frequency ͑p =0, ␥ =1͒ leads to solutions of Eq.…”

Section: ͑36͒mentioning

confidence: 97%

Colloquium: Physically based fluid modeling of collisionally dominated low-temperature plasmas

Robson

White

Petrović³

2005

Rev. Mod. Phys.

156

223

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This colloquium examines the theoretical modeling of nonequilibrium low-temperature ͑tens of thousands of degrees͒ plasmas, which involves a juxtaposition of three distinct fields: atomic and molecular physics, for the input of scattering cross sections; statistical mechanics, for the kinetic modeling; and electromagnetic theory, for the simultaneous solution of Maxwell's equations. Cross sections come either from single-scattering beam experiments or, at very low energies ͑Ͻ0.5 eV͒, from multiple-scattering experiments on "swarms" in gases-the free diffusion or large Debye length limit of a plasma, where they are embedded in transport coefficient data. The same Boltzmann kinetic theory that has been developed to a high level of sophistication over the past 50 years, specifically for the purpose of unfolding these transport data, can be employed for low-temperature plasmas with appropriate modification to allow for self-consistent rather than externally prescribed fields. A full kinetic treatment of low-temperature plasmas is, however, a daunting task and remains at the developmental level. Fortunately, since the accuracy requirements for modeling plasmas are generally much less stringent than for swarms, such a sophisticated phase-space treatment is not always necessary or desirable, and a computationally more efficient but correspondingly less accurate macroscopic theoretical model in configuration space at the fluid level is often considered sufficient. There has been a proliferation of such fluid modeling in recent times and this approach is now routinely used in the design and development of a large variety of plasma technologies, ranging from plasma display panels to plasma etching reactors for microelectronic device fabrication. However, many of these models have been developed empirically with specific applications in mind, and rigor and sophistication vary accordingly. In this colloquium, starting from the governing Boltzmann kinetic equation, a unified, general formulation of fluid equations is given for both ions and electrons in gaseous media with transparent and internally consistent approximations, all benchmarked against established results. Thereby a fluid model is obtained that is appropriate for practical application but at the same time is based on a firmer physical foundation. CONTENTS

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Hartree-Fock treatment of exchange in (e,2e) collisions

Cited by 23 publications

References 28 publications

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

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

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

Colloquium: Physically based fluid modeling of collisionally dominated low-temperature plasmas

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