Investigation of the cascades in atoms using the global characteristics of spectra

Karazija, R; Kučas, S.; Jonauskas, V.

doi:10.3952/lithjphys.44302

Cited by 8 publications

(11 citation statements)

References 84 publications

(139 reference statements)

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“…coincide with the values 61.4 eV and 114 eV calculated by multiconfiguration Dirac-Fock method [7]. Usually the method of global characteristics of spectra [13] is used for the calculation of ion yields produced by Auger cascade between complex configurations. However, the energy spectra of initial and final configurations of considered tungsten ions with vacancies in outermost shells are not distant energetically or they even overlap.…”

Section: Results Of Calculation and Their Discussionsupporting

confidence: 66%

Electron-impact double ionization of tungsten atoms and ions at low ionization stages

Jonauskas¹,

Kučas²,

Karazija³

2009

Lithuanian J. Phys.

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The double ionization of neutral tungsten atoms and W 2+ , W 4+ , and W 6+ ions by electron impact is investigated. The calculations are performed taking into account the Auger decay of single ionization states with inner vacancies in the 4d, 4f, 5s, 5p, and 5d shells as well as the direct double ionization using sudden perturbation model. The direct single ionization crosssection is obtained in relativistic distorted wave or binary-encounter-dipole approximations; the contribution from the indirect ionization by excitation-autoionization process is included too. It is shown that both processes-Auger decay of inner vacancy states and direct double ionization-play an important role in the double ionization process. The calculated cross-sections are compared with the experimental data.

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Section: Results Of Calculation and Their Discussionsupporting

confidence: 66%

Electron-impact double ionization of tungsten atoms and ions at low ionization stages

Jonauskas¹,

Kučas²,

Karazija³

2009

Lithuanian J. Phys.

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“…With such a modeling, more detailed structures appear in spectra, leading to a better agreement with recent 2p → 3d absorption experiments and improving in that way the temperature and density diagnostics. The analytical calculation of high-order (n ≥ 3) moments is possible (see the works of Karazija et al [18,19,20] and Oreg et al [21]), but difficult. An approximate method, relying on a physically realistic distribution of line amplitudes and energies, has been proposed in order to estimate the kurtosis.…”

Section: Resultsmentioning

confidence: 99%

“…However, some algorithms have been proposed in order to evaluate these high-order moments. Karazija et al [18,19,20] expressed the spectral moments by averages of the products of operators and formulated a general group-diagrammatic method for the evaluation of their explicit expressions. Oreg et al [21] used the fact that the moments reduce to configuration averages of n-boby symmetrical operators (nBSTOs).…”

Section: Complexity Of the Calculationmentioning

confidence: 99%

Effect of third- and fourth-order moments on the modeling of unresolved transition arrays

Pain

Gilleron

Bauche

et al. 2009

High Energy Density Physics

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The impact of the third (skewness) and fourth (kurtosis) reduced centered moments on the statistical modeling of E1 lines in complex atomic spectra is investigated through the use of Gram-Charlier, Normal Inverse Gaussian and Generalized Gaussian distributions. It is shown that the modeling of unresolved transition arrays with nonGaussian distributions may reveal more detailed structures, due essentially to the large value of the kurtosis. In the present work, focus is put essentially on the Generalized Gaussian, the power of the argument in the exponential being constrained by the kurtosis value. The relevance of the new statistical line distribution is checked by comparisons with smoothed detailed line-by-line calculations and through the analysis of 2p → 3d transitions of recent laser or Z-pinch absorption measurements. The issue of calculating high-order moments is also discussed (Racah algebra, Jucys graphical method, semi-empirical approach ...).

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“…These schemes are a representation of summation rules and reduction formulas. Although some computer programs exist (see for instance [27,28,29,30,31,32]), which are devoted to the reduction of graphs, it is easy to understand that the calculation becomes more and more cumbersome as the order of the moment increases. The n th -order moment reduces graphically to a polygone with (n+2) sides.…”

Section: Racah Algebra and Graphical Representationmentioning

confidence: 99%

“…Such expressions, which depend only on radial integrals, have been published by Bauche-Arnoult et al [40,42,43,44] for the moments µ n,c (centered moments with respect to µ 1 ) with n ≤ 3 of several kinds of transition arrays (relativistic or not). Karazija et al have proposed an algorithm in order to calculate the moments of a transition array using diagrammatic techniques [27,28,29].…”

Section: Statistical Descriptionmentioning

confidence: 99%

Characterization of anomalous Zeeman patterns in complex atomic spectra

Pain

Gilleron

2012

Phys. Rev. A

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The modeling of complex atomic spectra is a difficult task, due to the huge number of levels and lines involved. In the presence of a magnetic field, the computation becomes even more difficult. The anomalous Zeeman pattern is a superposition of many absorption or emission profiles with different Zeeman relative strengths, shifts, widths, asymmetries and sharpnesses. We propose a statistical approach to study the effect of a magnetic field on the broadening of spectral lines and transition arrays in atomic spectra. In this model, the σ and π profiles are described using the moments of the Zeeman components, which depend on quantum numbers and Landé factors. A graphical calculation of these moments, together with a statistical modeling of Zeeman profiles as expansions in terms of Hermite polynomials are presented. It is shown that the procedure is more efficient, in terms of convergence and validity range, than the Taylor-series expansion in powers of the magnetic field which was suggested in the past. Finally, a simple approximate method to estimate the contribution of a magnetic field to the width of transition arrays is proposed. It relies on our recently published recursive technique for the numbering of LS-terms of an arbitrary configuration.

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Investigation of the cascades in atoms using the global characteristics of spectra

Cited by 8 publications

References 84 publications

Electron-impact double ionization of tungsten atoms and ions at low ionization stages

Electron-impact double ionization of tungsten atoms and ions at low ionization stages

Effect of third- and fourth-order moments on the modeling of unresolved transition arrays

Characterization of anomalous Zeeman patterns in complex atomic spectra

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