Electron-impact excitation of Fe II: Effective collision strengths for optically allowed fine-structure transitions

Ramsbottom, Catherine

doi:10.1016/j.adt.2009.08.002

Cited by 13 publications

(18 citation statements)

References 25 publications

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“…The spectra of lowly ionized iron-peak elements such as (Fe q+ , Co q+ , Ni q+ , q = 0 − 3) are vitally important in astronomical observation. In particular, Ni 3+ being iso-electronic with Fe + , should produce many of the same diagnostic lines, which have extensively been studied previously by ; Zhang & Pradhan (1995); Ramsbottom et al (2005Ramsbottom et al ( , 2007; Ramsbottom (2009). Comparisons of these lines using the results of the present paper shall be made.…”

Section: Introductionsupporting

confidence: 65%

“…We appreciate the limitations of this small model, and also that it has taken another twenty years to include twenty more configurations in the configuration-interaction (CI) description of our present model. Ramsbottom et al (2005Ramsbottom et al ( , 2007; Ramsbottom (2009) also within an LS-coupling framework made a succession of calculations with a progressively better target description. They ultimately included orbitals up to n = 4 resulting in a total of 113 LS terms in their close coupling (CC) expansion.…”

Section: Introductionmentioning

confidence: 99%

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Spectroscopic diagnostics of low-ionized iron-peak elements. Electron-impact excitation of Ni3+ and photoionization of Ni2+

Fernández-Menchero

Smyth

Ramsbottom

et al. 2018

Monthly Notices of the Royal Astronomical Society

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The spectra from Fe-peak elements may be used to determine the temperature and density of various astrophysical objects. Determination of these quantities is underpinned by the accuracy and the comprehensiveness of the underlying atomic structure and collisional calculations. In the following paper, we shall focus specifically on Ni iv lines associated with transitions amongst several low-lying levels. We shall employ modified versions of the parallel Dirac R-matrix codes, considering both electron-impact excitation of Ni 3+ and the photoionisation of both the ground and excited states of Ni 2+ . We produce high-quality data sets for both processes, and using these data, we calculate line ratios relevant for plasma diagnostics of temperature and density.

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Section: Introductionsupporting

confidence: 65%

Section: Introductionmentioning

confidence: 99%

Spectroscopic diagnostics of low-ionized iron-peak elements. Electron-impact excitation of Ni3+ and photoionization of Ni2+

Fernández-Menchero

Smyth

Ramsbottom

et al. 2018

Monthly Notices of the Royal Astronomical Society

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“…Similar differences were reported by Ramsbottom (2009) for the low-lying 3d 7 fine-structure levels of Fe ii. Despite the high % differences found between these lowest levels in Table 1, overall the average % change across the 171 Sugar & Corliss (1985) Jπ symmetries is a more acceptable 6.2%.…”

Section: Target Description and Bound State Transitionssupporting

confidence: 68%

Photoionization of Co⁺and electron-impact excitation of Co^{2 +}using the DiracR-matrix method

Tyndall

Ramsbottom

Ballance

et al. 2016

Mon. Not. R. Astron. Soc.

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Modelling of massive stars and supernovae (SNe) plays a crucial role in understanding galaxies. From this modelling we can derive fundamental constraints on stellar evolution, mass-loss processes, mixing, and the products of nucleosynthesis. Proper account must be taken of all important processes that populate and depopulate the levels (collisional excitation, de-excitation, ionization, recombination, photoionization, bound-bound processes). For the analysis of Type Ia SNe and core collapse SNe (Types Ib, Ic and II) Fe group elements are particularly important. Unfortunately little data is currently available and most noticeably absent are the photoionization cross-sections for the Fe-peaks which have high abundances in SNe. Important interactions for both photoionization and electron-impact excitation are calculated using the relativistic Dirac Atomic R-matrix Codes (darc) for low ionization stages of cobalt. All results are calculated up to photon energies of 45 eV and electron energies up to 20 eV. The wavefunction representation of Co iii has been generated using grasp0 by including the dominant 3d 7 , 3d 6 [4s, 4p], 3p 4 3d 9 and 3p 6 3d 9 configurations, resulting in 292 fine structure levels. Electron-impact collision strengths and Maxwellian averaged effective collision strengths across a wide range of astrophysically relevant temperatures are computed for Co iii. In addition, statistically weighted level-resolved ground and metastable photoionization cross-sections are presented for Co ii and compared directly with existing work.

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“…6. We chose exci- tation of the 3d 6 4p 6 D o 9/2 and 3d 6 4p 6 F o 11/2 levels from the ground 3d 6 4s 6 D 9/2 level as these were also discussed by Zhang and Pradhan [9] and Ramsbottom et al [18]. Both of these transitions are the strong electric-dipole transitions, which exhibit the characteristic ln(E) behaviour almost at all energies.…”

Section: B Collision Strengths and Thermally Averaged Collision Strementioning

confidence: 99%

“…Later, Ramsbottom et al [17,18] performed a Breit-Pauli R-matrix (BPRM) calculation by including 262 fine-structure levels of the 100 LS terms belonging to the 3d 6 4s, 3d 7 , and 3d 6 4p configurations in the CC expansion. The results from the first calculation [17] are restricted to the transitions among the lowest 16 levels of Fe II corresponding to the 3d 6 4s 6 D, 3d 7 4 F, 3d 6 4s 4 D, and 3d 7 4 P multiplets, whereas the second calculation [18] included only the optically allowed lines for transitions from the 3d 6 4s and 3d 7 even-parity states to the 3d 6 4p odd-parity levels. Their target expansions included limited number of configurations, namely, the main spectroscopic configurations plus additional correlation effects incorporated via the single 3d 6 4d configuration.…”

Section: Introductionmentioning

confidence: 99%

Electron-impact excitation of forbidden and allowed transitions in Fe ii

Tayal

Zatsarinny

2018

Phys. Rev. A

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New extensive calculations are reported for electron collision strengths, rate coefficients, and transitions probabilities for a wide range of transitions in Fe II. The collision strengths were calculated in the close-coupling approximation using the B-spline Breit-Pauli R-matrix method. The multiconfiguration Hartree-Fock method in connection with adjustable configuration expansions and semi-empirical fine-tuning procedure is employed for an accurate representation of the target wave functions. The energy correction was also used in the scattering calculations by adding to Hamiltonian matrices prior to transformation to intermediate coupling. The spin-orbit interaction term was added to the final Hamiltonian matrices in scattering calculations. The close-coupling expansion contains 340 fine-structure levels of Fe II and includes all levels of the 3d 6 4s, 3d 5 4s 2 , 3d 7 , and 3d 6 4p configurations, plus a few lowest levels of the 3d 5 4s4p configuration. The effective collision strengths are obtained by averaging the electron collision strengths over a Maxwellian distribution of velocities at electron temperatures in the range from 10 2 to 10 5 K and are reported for all possible inelastic transitions between the 340 fine-structure levels. The present results are more extensive than the previous calculations and considerably expand the existing data sets for Fe II, allowing a more detailed treatment of the available measured spectra from different space observatories. Comparison with other calculations for collision rates and available experimental radiative rates is used to place uncertainty bounds on our collision strengths and to assess the likely uncertainties in the existing data sets.

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Electron-impact excitation of Fe II: Effective collision strengths for optically allowed fine-structure transitions

Cited by 13 publications

References 25 publications

Spectroscopic diagnostics of low-ionized iron-peak elements. Electron-impact excitation of Ni3+ and photoionization of Ni2+

Spectroscopic diagnostics of low-ionized iron-peak elements. Electron-impact excitation of Ni3+ and photoionization of Ni2+

Photoionization of Co⁺and electron-impact excitation of Co^{2 +}using the DiracR-matrix method

Electron-impact excitation of forbidden and allowed transitions in Fe ii

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Electron-impact excitation of Fe II: Effective collision strengths for optically allowed fine-structure transitions

Cited by 13 publications

References 25 publications

Spectroscopic diagnostics of low-ionized iron-peak elements. Electron-impact excitation of Ni3+ and photoionization of Ni2+

Spectroscopic diagnostics of low-ionized iron-peak elements. Electron-impact excitation of Ni3+ and photoionization of Ni2+

Photoionization of Co+and electron-impact excitation of Co2 +using the DiracR-matrix method

Electron-impact excitation of forbidden and allowed transitions in Fe ii

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Photoionization of Co⁺and electron-impact excitation of Co^{2 +}using the DiracR-matrix method