Dielectronic recombination from the ground and excited states of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi mathvariant="normal">C</mml:mi></mml:mrow><mml:mrow><mml:mn>4</mml:mn><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi mathvariant="normal">O</mml:mi></mml:mrow><mml:mrow><mml:mn>6</mml:mn><mml:mo>+</mml:mo>

Nr, Badnell; Ms, Pindzola; Dc, Griffin

doi:10.1103/physreva.41.2422

Cited by 39 publications

(17 citation statements)

References 23 publications

(1 reference statement)

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“…The total unified α R (T ) (solid curve) which include all possible contributions is, therefore, somewhat higher than that obtained from limited energy range. The LS coupling DR rate by Badnell et al (1990) (dot-dash curve) is lower than the others. The dashed and the long-dashed curves in the figure are RR rates by Aldrovandi & Pequignot (1973), and Verner and Ferland (1996); the latter agrees with the present rates at lower temperatures.…”

Section: Recombination Cross Sections and Rate Coefficientsmentioning

confidence: 87%

Electron‐Ion Recombination Rate Coefficients and Photoionization Cross Sections for Astrophysically Abundant Elements. IV. Relativistic Calculations for C iv and C v for Ultraviolet and X‐Ray Modeling

Nahar

Pradhan

Zhang

2000

ASTROPHYS J SUPPL S

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The first complete set of unified cross sections and rate coefficients are calculated for photoionization and recombination of He-and Li-like ions using the relativistic Breit-Pauli R-matrix method. We present total, unified (e + ion) recombination rate coefficients for (e + C V I −→ C V ) and(e + C V −→ C IV ) including fine structure. Level-specific recombination rate coefficients up to the n = 10 levels are also obtained for the first time; these differ considerably from the approximate rates currently available. Applications to recombination-cascade coefficients in X-ray spectral models of Kα emission from the important He-like ions are pointed out. The overall uncertainty in the total recombination rates should not exceed 10-20%. Ionization fractions for Carbon are recomputed in the coronal approximation using the new rates. The present (e + ion) recombination rate coefficients are compared with several sets of available data, including previous LS coupling results, and 'experimentally derived' rate coefficients. The role of relativistic fine structure, resolution of resonances, radiation damping, and interference effects is discussed. Two general features of recombination rates are noted: (i) the non-resonant (radiative recombination) peak as E, T → 0, and the (ii) the high-T resonant (di-electronic recombination) peak.

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Section: Recombination Cross Sections and Rate Coefficientsmentioning

confidence: 87%

Electron‐Ion Recombination Rate Coefficients and Photoionization Cross Sections for Astrophysically Abundant Elements. IV. Relativistic Calculations for C iv and C v for Ultraviolet and X‐Ray Modeling

Nahar

Pradhan

Zhang

2000

ASTROPHYS J SUPPL S

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“…The agreement is good in the low region since non-resonant cross sections dominate the low energy region. The dot-dashed curve is the DR rate by Badnell et al (1990) using the isolated resonance approximation. The sum of previous RR and DR rates agrees with the present unified rates to about 10-20%, as expected for highly charged ions.…”

Section: Recombination Cross Sections and Rate Coefficientsmentioning

confidence: 99%

Electron‐Ion Recombination Rate Coefficients and Photoionization Cross Sections for Astrophysically Abundant Elements. VII. Relativistic Calculations for O vi and O vii for Ultraviolet and X‐Ray Modeling

Nahar

Pradhan

2003

ASTROPHYS J SUPPL S

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Aimed at ionization balance and spectral analysis of UV and X-ray sources, we present self-consistent sets of photoionization cross sections, recombination cross sections, and rate coefficients for Li-like O VI and He-like O VII.Relativistic fine structure is considered through the Breit-Pauli R-matrix (BPRM) method in the close coupling approximation, implementing the unified treatment for total electron-ion recombination subsuming both radiative and di-electronic recombination processes. Self-consistency is ensured by using an identical wavefunction expansion for the inverse processes of photoionization and photo-recombination. Radiation damping of resonances, important for H-like and He-like core ions, is included. Compared to previous LS coupling results without radiative decay of low-n n ≤ 10) resonances, the presents results show significant reduction in O VI recombination rates at high temperatures.In addition to the total rates, level-specific photoionization cross sections and recombination rates are presented for all fine structure levels n (ℓ SLJ) up to n ≤ 10, to enable accurate computation of recombination-cascade matrices and spectral formation of prominent UV and X-ray lines such as the 1032,1038Å doublet of O VI, and the 'triplet' forbidden, intercombination, and resonance X-ray lines of O VII at 22.1, 21.8, and 21.6Å respectively. Altogether, atomic parameters for 98 levels of O VI and 116 fine structure levels of O VII are theoretically computed. These data should provide a reasonably complete set of photoionization and recombination rates in collisional or radiative equilibrium.

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“…To see this, just substitute for qf from Eq. (6) into Eq. (5) and use, for example, a Bethe-Salpetertype [27] approximation for the radiative-recombination cross section.…”

Section: Theorymentioning

confidence: 99%

Unified dielectronic and radiative-recombination cross sections forU90+

Badnell

Pindzola

1992

Phys. Rev. A

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We have calculated unified photorecombination cross sections and independent-processes photorecombination cross sections for U + in the vicinity of the KLL resonances. For this case, where the radiative width of a level dominates the Auger width, we find relatively strong interference e6'ects between the direct (radiative) and indirect (dielectronic) recombination processes. In particular, we find that the unified photorecombination cross section for the 1s +e~1s 2s+hv line is suppressed by a factor of 2 in the presence of the 1s2s(1)2p( -') resonance. Overall, however, the KLL recombination cross section is reduced by only 2-3 %, at most.PACS number(s): 34.80.Kw

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Dielectronic recombination from the ground and excited states ofC4+andO6+

Cited by 39 publications

References 23 publications

Electron‐Ion Recombination Rate Coefficients and Photoionization Cross Sections for Astrophysically Abundant Elements. IV. Relativistic Calculations for C iv and C v for Ultraviolet and X‐Ray Modeling

Electron‐Ion Recombination Rate Coefficients and Photoionization Cross Sections for Astrophysically Abundant Elements. IV. Relativistic Calculations for C iv and C v for Ultraviolet and X‐Ray Modeling

Electron‐Ion Recombination Rate Coefficients and Photoionization Cross Sections for Astrophysically Abundant Elements. VII. Relativistic Calculations for O vi and O vii for Ultraviolet and X‐Ray Modeling

Unified dielectronic and radiative-recombination cross sections forU90+

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