Atomic data from the Iron project LXIV: Radiative transition rates and collision strengths for Ca II

M. Meléndez, M.A. Bautista, N.R. Badnell

Research output: Contribution to journalArticle

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Abstract

Aims.This work reports radiative transition rates and electron impact excitation rate coefficients for levels of the n = 3, 4, 5, 6, 7, 8 configurations of . Methods.The radiative data were computed using the Thomas-Fermi-Dirac central potential method in the frozen core approximation and includes the polarization interaction between the valence electron and the core using a model potential. This method allows for configuration interactions (CI) and relativistic effects in the Breit-Pauli formalism. Collision strengths in LS-coupling were calculated in the close coupling approximation with the R-matrix method. Then, fine structure collision strengths were obtained by means of the intermediate-coupling frame transformation (ICFT) method which accounts for spin-orbit coupling effects. Results. We present extensive comparisons with the most recent calculations and measurements for as well as a comparison between the core polarization results and the "unpolarized" values. We find that core polarization affects the computed lifetimes by up to 20%. Our results are in very close agreement with recent measurements for the lifetimes of metastable levels. The present collision strengths were integrated over a Maxwellian distribution of electron energies and the resulting effective collision strengths are given for a wide range of temperatures. Our effective collision strengths for the resonance transitions are within ~11% from previous values derived from experimental measurements, but disagree with later computations using the distorted wave approximation.
Original languageEnglish
Pages (from-to)1203-1209
Number of pages6
JournalAstronomy and Astrophysics
Volume469
DOIs
Publication statusPublished - 2007

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collision
iron
collisions
polarization
electron
approximation
life (durability)
Maxwell-Boltzmann density function
relativistic effects
matrix methods
configuration interaction
electron impact
fine structure
rate
method
project
electron energy
formalism
valence
orbits

Keywords

  • atomic data
  • atomic processes
  • iron
  • transition rates
  • collison strengths

Cite this

@article{651a19490b4b43e0989860dfa55015b2,
title = "Atomic data from the Iron project LXIV: Radiative transition rates and collision strengths for Ca II",
abstract = "Aims.This work reports radiative transition rates and electron impact excitation rate coefficients for levels of the n = 3, 4, 5, 6, 7, 8 configurations of . Methods.The radiative data were computed using the Thomas-Fermi-Dirac central potential method in the frozen core approximation and includes the polarization interaction between the valence electron and the core using a model potential. This method allows for configuration interactions (CI) and relativistic effects in the Breit-Pauli formalism. Collision strengths in LS-coupling were calculated in the close coupling approximation with the R-matrix method. Then, fine structure collision strengths were obtained by means of the intermediate-coupling frame transformation (ICFT) method which accounts for spin-orbit coupling effects. Results. We present extensive comparisons with the most recent calculations and measurements for as well as a comparison between the core polarization results and the {"}unpolarized{"} values. We find that core polarization affects the computed lifetimes by up to 20{\%}. Our results are in very close agreement with recent measurements for the lifetimes of metastable levels. The present collision strengths were integrated over a Maxwellian distribution of electron energies and the resulting effective collision strengths are given for a wide range of temperatures. Our effective collision strengths for the resonance transitions are within ~11{\%} from previous values derived from experimental measurements, but disagree with later computations using the distorted wave approximation.",
keywords = "atomic data, atomic processes, iron, transition rates, collison strengths",
author = "M. Mel{\'e}ndez and M.A. Bautista and N.R. Badnell",
year = "2007",
doi = "10.1051/0004-6361:20077262",
language = "English",
volume = "469",
pages = "1203--1209",
journal = "Astronomy and Astrophysics",
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}

Atomic data from the Iron project LXIV: Radiative transition rates and collision strengths for Ca II. / Meléndez, M.; Bautista, M.A.; Badnell, N.R.

In: Astronomy and Astrophysics, Vol. 469, 2007, p. 1203-1209.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Atomic data from the Iron project LXIV: Radiative transition rates and collision strengths for Ca II

AU - Meléndez, M.

AU - Bautista, M.A.

AU - Badnell, N.R.

PY - 2007

Y1 - 2007

N2 - Aims.This work reports radiative transition rates and electron impact excitation rate coefficients for levels of the n = 3, 4, 5, 6, 7, 8 configurations of . Methods.The radiative data were computed using the Thomas-Fermi-Dirac central potential method in the frozen core approximation and includes the polarization interaction between the valence electron and the core using a model potential. This method allows for configuration interactions (CI) and relativistic effects in the Breit-Pauli formalism. Collision strengths in LS-coupling were calculated in the close coupling approximation with the R-matrix method. Then, fine structure collision strengths were obtained by means of the intermediate-coupling frame transformation (ICFT) method which accounts for spin-orbit coupling effects. Results. We present extensive comparisons with the most recent calculations and measurements for as well as a comparison between the core polarization results and the "unpolarized" values. We find that core polarization affects the computed lifetimes by up to 20%. Our results are in very close agreement with recent measurements for the lifetimes of metastable levels. The present collision strengths were integrated over a Maxwellian distribution of electron energies and the resulting effective collision strengths are given for a wide range of temperatures. Our effective collision strengths for the resonance transitions are within ~11% from previous values derived from experimental measurements, but disagree with later computations using the distorted wave approximation.

AB - Aims.This work reports radiative transition rates and electron impact excitation rate coefficients for levels of the n = 3, 4, 5, 6, 7, 8 configurations of . Methods.The radiative data were computed using the Thomas-Fermi-Dirac central potential method in the frozen core approximation and includes the polarization interaction between the valence electron and the core using a model potential. This method allows for configuration interactions (CI) and relativistic effects in the Breit-Pauli formalism. Collision strengths in LS-coupling were calculated in the close coupling approximation with the R-matrix method. Then, fine structure collision strengths were obtained by means of the intermediate-coupling frame transformation (ICFT) method which accounts for spin-orbit coupling effects. Results. We present extensive comparisons with the most recent calculations and measurements for as well as a comparison between the core polarization results and the "unpolarized" values. We find that core polarization affects the computed lifetimes by up to 20%. Our results are in very close agreement with recent measurements for the lifetimes of metastable levels. The present collision strengths were integrated over a Maxwellian distribution of electron energies and the resulting effective collision strengths are given for a wide range of temperatures. Our effective collision strengths for the resonance transitions are within ~11% from previous values derived from experimental measurements, but disagree with later computations using the distorted wave approximation.

KW - atomic data

KW - atomic processes

KW - iron

KW - transition rates

KW - collison strengths

UR - http://arxiv.org/PS_cache/arxiv/pdf/0704/0704.3807v1.pdf

U2 - 10.1051/0004-6361:20077262

DO - 10.1051/0004-6361:20077262

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SP - 1203

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