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Kastner, S. O.; Crooker, A. M.; Behring, W. E.; Cohen, Lisa R.

doi:10.1103/physreva.16.577

Cited by 27 publications

(13 citation statements)

References 12 publications

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“…The measured energies differ by up to 0.2 eV from those already reported in the literature [19,20]; cf. Table I.…”

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confidence: 50%

“…Very few data are available for the Ar-like ions K 1 and Ca 21 [19][20][21][22][23] because of the extreme difficulty of obtaining and maintaining a sufficient density of ions. Using a pioneering experimental technique of crossed ion and synchrotron radiation beams [24], Peart and Lyon measured the photoionization cross section of K 1 in the region of 3s-subshell excitations [21].…”

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confidence: 99%

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Dramatic Changes in the3sAutoionization Process at the Beginning of the Ar I Sequence

et al. 1997

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The 3s ! np resonances were observed to change dramatically in appearance with increasing ionization along the Ar I sequence, and within the 3s ! np channel of In recent years, photoionization of the outer s-subshell electrons in argon has attracted considerable interest [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18], and a rather complete picture of 3s photoionization has been drawn from the 3s ! np, 3s !´p, and satellite spectra, both experimentally [2-8] and theoretically [9][10][11][12][13][14][15][16][17][18]. The cross sections of the individual processes are crucial since they depend strongly on electron correlation effects and therefore provide a sensitive test of modern theoretical and computational physics. Further valuable insight into these effects may be obtained by studying the evolution of inner shell excitation behavior along the isoelectronic sequence.Very few data are available for the Ar-like ions K 1

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“…The measured energies differ by up to 0.2 eV from those already reported in the literature [19,20]; cf. Table I.…”

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confidence: 50%

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confidence: 99%

Dramatic Changes in the3sAutoionization Process at the Beginning of the Ar I Sequence

et al. 1997

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“…and Al 31 resonance features were also recorded [13]. All data to date for ions in this sequence were recorded photographically and, particularly for Al 31 , were masked by emission features.…”

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Anomalous Behavior of the Near-Threshold Photoionization Cross Section of the Neon Isoelectronic Sequence: A Combined Experimental and Theoretical Study

et al. 1999

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We present a combined theoretical and experimental investigation of photoionization along the Ne isoelectronic sequence and show that the near-threshold behavior of the cross section for Si 41 differs radically from the nearby ions in the sequence. We demonstrate that the general nature of the underlying physics implies that dramatic changes in near-threshold behavior may be expected for many other ions. PACS numbers: 32.80.Fb, 32.80.Hd, 52.25.Qt The response of positive ions to ionizing radiation, the fundamental process of photoionization, is a dominant process in the universe. However, it is largely unexplored experimentally due to the difficulty of producing and maintaining appropriate densities of multiply charged ions, along with the requirement for high-flux sources in the extreme UV and x-ray ranges [1,2]. Photoionization is particularly attractive for theoretical interpretation due to (i) selectivity, owing to dipole selection rules, (ii) the fact that the photon disappears, thereby simplifying the final state, and (iii) the weak coupling between the photon and target electrons, allowing focus on the many-body aspects of the electron-electron interactions of the target ion [3][4][5].From a fundamental point of view, positive ions provide a "laboratory" to investigate the dynamic interplay between many-body electron-electron correlations, electron-nucleus interactions, and relativistic effects by looking along an ionic sequence. With increasing ionization, as the electron-nucleus interactions dominate, the photoionization behavior will tend towards hydrogenic; however, this trend towards simplicity is not at all monotonic, and very significant changes in the cross section behavior may occur for particular ions. In this Letter, we report the first combined theoretical and experimental investigation of photoionization along the Ne isoelectronic sequence and show that the near-threshold behavior of the cross section for Si 41 differs radically from the nearby ions in the sequence. We demonstrate that the general nature of the underlying physics implies that dramatic changes in near-threshold behavior may be expected for many other ions.Photoionization of the Ne isoelectronic sequence, aside from its importance as the response of the simplest noble gas structure with multiple shells ͑1s 2 2s 2 2p 6 ͒ to ionizing radiation, is also of particular interest owing to the significant cosmic abundance of Ne, Na . Furthermore, the study of photoionization provides information on the inverse processes of radiative and dielectronic recombination which are of importance in modeling astrophysical [7] and laboratory [8] plasmas, particularly for low-energy electrons corresponding to the near-threshold region, which is the focus of this Letter.Following the pioneering work of Codling et al. [9], several extensive experimental investigations on neutral Ne have been carried out, aided by the relative simplicity of working with a gas and recent developments in storage ring sources [10]. For ions of the Ne sequence, previo...

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“…There are many solar observations of these lines including the work of Zirin (1964), Feldman et al (1965), andQuinet (2000). Kastner et al (1977). Lin et al (1977) calculated the relativistic electric dipole oscillator strengths in length and velocity forms for the 3p 6 -3p 5 nd (n ¼ 3, 4) and 3p 6 -3p 5 4s transitions in Fe ix.…”

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New Relativistic Atomic Data for Fe ix

Verma¹,

Jha²,

Mohan³

2006

ASTROPHYS J SUPPL S

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A large-scale configuration interaction (CI) calculation using Program CIV3 of Hibbert is performed for the lowest 87 fine-structure levels of argon-like iron ions. We have calculated energy levels, oscillator strengths, and transition probabilities for all electric-dipole-allowed and intercombination transitions between the levels of 3s 3p 5 5d states of Fe ix in the LSJ coupling scheme. Lifetimes of the 3d levels are also determined. The calculations include the major correlation effects. We attempt to correct the inaccuracies in the CI coefficients in the wave functions, which would lead to inaccuracy in transition probabilities by applying a ''fine-tuning'' technique. The relativistic effects are incorporated by adding mass correction, Darwin term, and spin-orbit interaction terms to the nonrelativistic Hamiltonian in the Breit-Pauli approximations. The present results are in good agreement with other available calculations and experiments. We predict new data for several levels where no other theoretical or experimental results are available. We hope our extensive calculations will be useful to experimentalists in identifying the fine-structure levels in their future work.

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Observation of autoionizing transitionsns2np6−nsnp

Cited by 27 publications

References 12 publications

Dramatic Changes in the3sAutoionization Process at the Beginning of the Ar I Sequence

Dramatic Changes in the3sAutoionization Process at the Beginning of the Ar I Sequence

Anomalous Behavior of the Near-Threshold Photoionization Cross Section of the Neon Isoelectronic Sequence: A Combined Experimental and Theoretical Study

New Relativistic Atomic Data for Fe ix

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