Energy levels, oscillator strengths and lifetimes in Ar V

Abstract

We have calculated the excitation energies, oscillator strengths and transition probabilities for electric-dipole-allowed and intercombination transitions among the 46 LS levels belonging to the configurations 3s 2 3p 2 , 3s3p 3 , 3s 2 3p3d, 3p 4 , 3s 2 3p4s, 3s 2 3p4p, 3s3p 2 ( 2 S)4s, 3s3p 2 ( 2 P)4s, 3s3p 2 ( 4 P)4s, 3s3p 2 ( 2 D)4s, 3s 2 3p4d and 3s 2 3p4f of Si-like Argon. These states are represented by extensive Configuration-Interaction (CI) wavefunctions obtained using the CIV3 computer code of Hibbert. From our transition probabilities we have also calculated the radiative lifetimes of singlet and triplet states of Ar V. Our results are compared with other available theoretical calculations and experimental data. To assess the importance of relativistic effects on our calculated values, we have also carried out calculations in the intermediate-coupling scheme using the Breit-Pauli Hamiltonian. Small adjustments to the diagonal elements of the Hamiltonian matrices have been made so that the energy splittings are as close as possible to the experimentally compiled energy values of the National Institute for standards and Technology (NIST). The energy splitting of 85 fine-structure levels, the oscillator strengths and transition probabilities for electric-dipole-allowed and intercombination transitions and the lifetimes of some finestructure levels are presented and compared with available experimental and other theoretical values. In this calculation, we also predict new data for several fine-structure levels where no other theoretical and experimental results are available.

BD–22°3467, a DAO-type star exciting the nebula Abell 35

“…From this value, we calculated f -values of 4.7037 · 10 −2 , 1.4111 · 10 −2 , and 2.3518 · 10 −2 for the three fine-structure components. A comparison with recent work of Tayal et al (2009Tayal et al ( , f 1371 = 2.257·10 −2 and 2.834·10 −2 ) shows good agreement with the OpacityProject. Thus, the reason for the disagreement of the Ar V lines remains unknown.…”

Quantum mechanical Stark widths for Ar v and Ar vi lines: scaling with temperature

“…We present in Tables 3 and 4 our radiative decay rates A ji , absorption oscillator strengths f ij and line strengths S of the considered lines with their comparisons. The averaged agreement (for the three parameters A ji , f ij , and S) for the 12 Ar V lines is about 40 per cent with the MCHF results (Froese Fischer et al 2006), and it is better with the CIV3 results (Tayal et al 2009) where the agreement is about 25 per cent.…”

“…The classical angular momentum L = ρmv can be related to the eigenvalues of the corresponding quantum-mechanical operator L 2 by Table 1. Some of our level energies (E) in cm −1 for the Ar V ion compared to the CIV3 (Tayal et al 2009), to the MCHF (Froese Fischer et al 2006), to the MCDF (Kohstall et al 1998), and to the NIST (Kramida et al 2017) using that E = 1 2 mv 2 = 3 2 k B T , we find…”

“…For Ar VI (Al-like ion), we have used eight configurations: 1s 2 2s 2 2p 6 (3s 2 3p, 3s3p 2 , 3s 2 3d, 3p 3 , 3s3p3d, 3s 2 4s, 3s 2 4p, 3s 2 4f) giving rise to 67 fine structure levels. To check our intermediate results, we compare our Ar v data to the multiconfiguration Hartree−Fock (MCHF) calculations performed in Froese Fischer, Tachiev & Irimia (2006) using the five configurations 1s 2 2s 2 2p 6 (3s 2 3p 2 , 3s3p 3 , 3s 2 3p3d, 3s 2 3p4s, 3p 4 ), to the CIV3 calculations performed in Tayal, Gupta & Tripathi (2009) using nine configurations (besides the six configurations used in our calculations, they added 3s 2 3p4p, 3s 2 3p4s, and 3s 2 3p4d), and to the multiconfiguration Dirac−Fock (MCDF) calculations performed in Kohstall et al (1998). We compare also with the NIST (Kramida et al 2017) results originally from Saloman (2010).…”

Fine-structure energy levels, oscillator strengths and lifetimes in Cu XVI

“…Vilkas and Ishikawa [20] carried out relativistic multireference many-body perturbation theory [21] calculations for the term energies of the ground and 26 lowest excited levels arising from the 3s 2 3p 2 , 3s3p 3 and 3s 2 3p3d configurations in silicon-like ions with nuclear charges Z = 24-30. Tayal and Gupta carried out calculations of excitation energies, oscillator strengths, transition probabilities and lifetimes for electric-dipole-allowed and inter-combination transitions in silicon-like Ca VII [22] and Ar V [23], using the CI code [24] and the Breit-Pauli Hamiltonian [25]. The spectrum of the Cu XVI ion has been studied by several workers [26][27][28][29][30][31][32].…”