- ID:
- ivo://CDS.VizieR/J/ApJS/123/295
- Title:
- Electron impact excitation in Fe XI
- Short Name:
- J/ApJS/123/295
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Collision strengths for electron impact excitation of fine-structure levels in sulfur-like Fe XI are calculated in a semirelativistic R-matrix approach. The 38 fine-structure levels arising from the 20 LS states 3s^2^3p^4^ ^3^P, ^1^D, ^1^S; 3s3p^5^ ^3^P^0^, ^1^P^0^; 3s^2^3p^3^(^4^S^0^)3d ^3^D^0^, 3s^2^3p^3^(^2^P^0^)3d ^1,3^P^0^, ^1,3^D^0^, ^1,3^F^0^, 3s^2^3p^3^(^2^D^0^)3d ^1,3^S^0^, ^1,3^P^0^, ^1,3^D^0^, ^1,3^F^0^ are included in our calculation. The target levels are represented by configuration interaction wave functions. The relativistic effects are considered in the Breit-Pauli approximation by including one-body mass correction, Darwin term, and spin-orbit terms in the scattering equations. Collision strengths for transitions from the 3s^2^3p^4^ ^3^P_2,1,0_ levels to the fine-structure levels of the 3s^2^3p^3^3d configuration are compared with the distorted-wave results of Bhatia & Doschek (1996) at 8.0, 16.0, 24.0 ryd. There are some significant discrepancies between the two calculations, mostly caused by the difference in target wave functions. The collision strengths are integrated over a Maxwellian distribution of electron energies to obtain effective collision strengths over the temperature range from 5x10^5^ to 5x10^6^ K.
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- ID:
- ivo://CDS.VizieR/J/A+A/432/1151
- Title:
- Electron impact excitation of Al XIII
- Short Name:
- J/A+A/432/1151
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Energy levels, radiative rates, collision strengths, and effective collision strengths for all transitions up to and including the n=5 levels of Al XIII have been computed in the jj coupling scheme including relativistic effects. All partial waves with angular momentum J<=60 have been included, and resonances have been resolved in a fine energy grid in the threshold region. Collision strengths are tabulated at energies above thresholds in the range 170.0<=E<=300.0Ryd, and results for effective collision strengths, obtained after integrating the collision strengths over a Maxwellian distribution of electron velocities, are tabulated over a wide temperature range of 4.4<=logT_e_<=6.8K. The importance of including relativistic effects in a calculation is disc ussed in comparison with the earlier available non-relativistic results.
- ID:
- ivo://CDS.VizieR/J/A+A/500/1253
- Title:
- Electron-impact excitation of ArIII
- Short Name:
- J/A+A/500/1253
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Emission from Ar III is seen in planetary nebulae, in H II regions, and from laboratory plasmas. The analysis of such spectra requires accurate electron impact excitation data. The aim of this work is to improve the electron impact excitation data available for Ar^2+^, for application in studies of planetary nebulae and laboratory plasma spectra. The effects of the new data on diagnostic line ratios are also studied. Electron-impact excitation collision strengths have been calculated using the R-Matrix Intermediate-Coupling Frame-Transformation method and the R-Matrix Breit-Pauli method. Excitation cross sections are calculated between all levels of the configurations 3s^2^3p^4^, 3s3p^5^, 3p^6^, 3p^5^3d, and 3s^2^3p^3^nl (3d<=nl<=5s). Maxwellian effective collision strengths are generated from the collision strength data.
- ID:
- ivo://CDS.VizieR/J/A+A/441/831
- Title:
- Electron impact excitation of Ar XVII
- Short Name:
- J/A+A/441/831
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Energies for the lowest 49 levels among the 1s^2 and 1snl (n=2-5) configurations of Ar XVII have been calculated using the GRASP code of Dyall et al. (1989, Comput. Phys. Commun., 55, 424). Additionally, radiative rates, oscillator strengths, and line strengths are calculated for all electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2), and magnetic quadrupole (M2) transitions among these levels. Furthermore, collision strengths have also been calculated for all the 1176 transitions among the above 49 levels using the Dirac Atomic R-matrix Code (DARC) of Norrington & Grant (2005, Comput. Phys. Commun., in prep.), over a wide energy range up to 580Ryd. Resonances have been resolved in the threshold region, and effective collision strengths have been obtained over a wide temperature range up to log T_e_=7.2K. Comparisons are made with the limited results available in the literature, and the accuracy of the data is assessed. Our energy levels are estimated to be accurate to better than 0.1%, whereas results for other parameters are probably accurate to better than 20%.
- ID:
- ivo://CDS.VizieR/J/A+A/487/1203
- Title:
- Electron-impact excitation of Be-like Mg
- Short Name:
- J/A+A/487/1203
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an R-matrix calculation of electron-impact excitation of Be-like Mg. The calculation is similar to that one presented for Be-like Fe by Chidichimo et al. (2005A&A...430..331C), and was done with the intermediate-coupling frame transformation method and including a total of 98 fine-structure levels, up to n=4. ************************************************************************** * * * Sorry, but the author(s) never supplied the tabular material * * announced in the paper * * * **************************************************************************
- ID:
- ivo://CDS.VizieR/J/ApJS/196/24
- Title:
- Electron-impact excitation of CrII
- Short Name:
- J/ApJS/196/24
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we present electron-impact excitation collision strengths and Maxwellian averaged effective collision strengths for the complicated iron-peak ion CrII. We consider specifically the allowed lines for transitions from the 3d^5^ and 3d^4^4s even parity configuration states to the 3d^4^4p odd parity configuration levels. The parallel suite of R-Matrix packages, RMATRX II, which have recently been extended to allow for the inclusion of relativistic effects, were used to compute the collision cross sections. A total of 108 LS{pi}/280J{pi} levels from the basis configurations 3d^5^, 3d^4^4s, and 3d^4^4p were included in the wavefunction representation of the target including all doublet, quartet, and sextet terms. Configuration interaction and correlation effects were carefully considered by the inclusion of seven more configurations and a pseudo-corrector {overline}4d type orbital. The 10 configurations incorporated into the CrII model thus listed are 3d^5^, 3d^4^4s, 3d^4^4p, 3d^3^4s^2^, 3d^3^4p^2^, 3d^3^4s4p, 3d^4^{overline}{4d}, 3d^3^4s{overline}{4d}, 3d^3^4p{overline}{4d}, and 3d^3^{overline}{4d}^2^, constituting the largest CrII target model considered to date in a scattering calculation. The Maxwellian averaged effective collision strengths are computed for a wide range of electron temperatures 2000-100000K which are astrophysically significant. Care has been taken to ensure that the partial wave contributions to the collision strengths for these allowed lines have converged with "top-up" from the Burgess-Tully sum rule incorporated. Comparisons are made with the results of Bautista et al. and significant differences are found for some of the optically allowed lines considered.
- ID:
- ivo://CDS.VizieR/J/A+A/466/763
- Title:
- Electron-impact excitation of Fe^19+^
- Short Name:
- J/A+A/466/763
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results for the electron-impact excitation of N-like Fe as part of the RmaX network. R-matrix theory using an intermediate-coupling frame transformation method is used to obtain level-resolved collision strengths. Separate calculations are performed using different target expansions. The first is a 215 level close-coupling calculation which has the 2s^2^ 2p^3^, 2s 2p^4^, 2p^5^, 2s^2^ 2p^2^ 3l, and 2s 2p^3^ 3l configurations while the second calculation also includes the levels from the 2s^2^ 2p^2^ 4l configurations for a total of 302 close-coupling levels. The effect of the additional resonant enhancement of the larger calculation is explored and compared with a previous IRON Project report and other, more recent, calculations. As a final comparison, we model an astrophysical plasma using the results of the present calculations and previous work.
- ID:
- ivo://CDS.VizieR/J/A+A/418/371
- Title:
- Electron impact excitation of Fe XIII
- Short Name:
- J/A+A/418/371
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Energy levels and radiative rates for transitions among the lowest 97 fine-structure levels belonging to the (1s^2^2s^2^2p^6^) 3s^2^3p^2^, 3s3p^3^, 3s^2^3p3d , 3p^4^, 3s3p^2^3d and 3s^2^3d^2^ configurations of Fe XIII have been calculated using the fully relativistic GRASP code. Additionally, collision strengths for transitions among these levels have been computed using the Dirac Atomic R-matrix Code (DARC) of Norrington & Grant (2004, Comput. Phys. Commun., in prep.). Radiative rates and oscillator strengths are tabulated for all allowed transitions among the 97 fine-structure levels, while collision strengths are reported for some transitions at a few energies above thresholds. Comparisons are made with the available results, and the accuracy of the data is assessed.
- ID:
- ivo://CDS.VizieR/J/A+A/420/783
- Title:
- Electron impact excitation of Fe XVII
- Short Name:
- J/A+A/420/783
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Energies of the lowest 157 levels belonging to the (1s^2^) 2s ^2^2p^6^, 2s ^2^2p ^5^3l, 2s ^2^2p ^5^4l, 2s ^2^2p ^5^5l, 2s2p ^6^3l, 2s2p ^6^4l and 2s2p ^6^5l configurations of Fe XVII have been calculated using the GRASP code of Dyall et al. (1989, Comput. Phys. Commun., 55, 424). Additionally, radiative rates, oscillator strengths, and line strengths are calculated for all electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2), and magnetic quadrupole (M2) transitions among these levels. Comparisons are made with the results already available in the literature, and the accuracy of the data is assessed. Our energy levels are expected to be accurate to better than 1%, whereas results for other parameters are probably accurate to better than 20%.
- ID:
- ivo://CDS.VizieR/J/A+A/526/A115
- Title:
- Electron-impact excitation of H-like ions
- Short Name:
- J/A+A/526/A115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Accurate atomic data for the less abundance Fe-peak elements are required for use in X-ray astrophysical studies. We calculate high quality electron-impact excitation collision strengths and effective collision strengths for hydrogenic Cr, Mn, Fe, Co, and Ni. We use the Dirac R-matrix method, the intermediate coupling frame transformation R-matrix method, the semi-relativistic distorted-wave method and the fully-relativistic distorted-wave method to calculate collision strengths for each of the ions. The ADAS collisional-radiative codes are used to produce photon emissivity coefficients for each ion.