Multiple ionization of magnesium by electron impact

McCallion, P; Shah, M B; Gilbody, H B

doi:10.1088/0953-4075/25/5/016

Cited by 43 publications

(70 citation statements)

References 11 publications

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“…We observe that the maximum of single ionization for d = 2 and d = 3 is obtained for 0 close to |E g | which is qualitatively consistent with the experimental data of Ref. [5]. In Sec.…”

Section: B the Probability Curvessupporting

confidence: 91%

Single and double ionization of magnesium by electron impact: A classical study

et al. 2017

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International audienceWe consider electron impact-driven single and double ionization of magnesium in the 10-100 eV energy range. Our classical Hamiltonian model of these (e, 2e) and (e, 3e) processes sheds light on their total cross sections and reveals the underlying ionization mechanisms. Two pathways are at play in single ionization: Delayed and direct. In contrast, only the direct process is observed in double ionization, ruling out the excitation-autoionization channel. We also provide evidence that the so-called TS2 (Two-Step 2) mechanism predominates over the TS1 (Two-Step 1) mechanism, in agreement with experiments

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“…We observe that the maximum of single ionization for d = 2 and d = 3 is obtained for 0 close to |E g | which is qualitatively consistent with the experimental data of Ref. [5]. In Sec.…”

Section: B the Probability Curvessupporting

confidence: 91%

Single and double ionization of magnesium by electron impact: A classical study

et al. 2017

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“…The observations for neutral Mg i (Freund et al 1990;McCallion et al 1992a) show no evidence for EA and therefore we neglected this process for neutral Mg. The available measurements (Chung 1996;Bernhardt et al 2014) show EA enhancements that are consistent with the above scaling.…”

Section: Ea Contributionmentioning

confidence: 99%

X-ray emission from thin plasmas

Urdampilleta

Kaastra

Mehdipour

2017

A&A

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Every observation of astrophysical objects involving a spectrum requires atomic data for the interpretation of line fluxes, line ratios, and ionization state of the emitting plasma. One of the processes that determines it is collisional ionization. In this study, an update of the direct ionization (DI) and excitation-autoionization (EA) processes is discussed for the H to Zn-like isoelectronic sequences. In recent years, new laboratory measurements and theoretical calculations of ionization cross-sections have become available. We provide an extension and update of previous published reviews in the literature. We include the most recent experimental measurements and fit the cross-sections of all individual shells of all ions from H to Zn. These data are described using an extension of Younger's and Mewe's formula, suitable for integration over a Maxwellian velocity distribution to derive the subshell ionization rate coefficients. These ionization rate coefficients are incorporated in the high-resolution plasma code and spectral fitting tool SPEX V3.0.

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“…1 we complement Seaton's comparisons with new comparisons with modern experimental data from the Queen's University of Belfast laboratory for the cases of electron impact ionization of ground state hydrogen, oxygen, magnesium and iron (Shah et al 1987;Thompson et al 1995;McCallion et al 1992;Shah et al 1993, respectively). These experimental data are in good agreement with other experiments, cover Shah et al (1987); Thompson et al (1995);McCallion et al (1992); Shah et al (1993), respectively. The plot shows the ratio of the experimental values with respect to the theoretical cross section, plotted against the collision energy E scaled by the ionization energy I.…”

Section: The Classical Drawin Formulamentioning

confidence: 99%

On inelastic hydrogen atom collisions in stellar atmospheres

Barklem

Belyaev²,

Guitou³

et al. 2011

A&A

109

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The influence of inelastic hydrogen atom collisions on non-LTE spectral line formation has been, and remains to be, a significant source of uncertainty for stellar abundance analyses, due to the difficulty in obtaining accurate data for low-energy atomic collisions either experimentally or theoretically. For lack of a better alternative, the classical "Drawin formula" is often used. Over recent decades, our understanding of these collisions has improved markedly, predominantly through a number of detailed quantum mechanical calculations. In this paper, the Drawin formula is compared with the quantum mechanical calculations both in terms of the underlying physics and the resulting rate coefficients. It is shown that the Drawin formula does not contain the essential physics behind direct excitation by H atom collisions, the important physical mechanism being quantum mechanical in character. Quantitatively, the Drawin formula compares poorly with the results of the available quantum mechanical calculations, usually significantly overestimating the collision rates by amounts that vary markedly between transitions.

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Multiple ionization of magnesium by electron impact

Cited by 43 publications

References 11 publications

Single and double ionization of magnesium by electron impact: A classical study

Single and double ionization of magnesium by electron impact: A classical study

X-ray emission from thin plasmas

On inelastic hydrogen atom collisions in stellar atmospheres

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