The spin-allowed and spin-forbidden - , transitions in the magnesium isoelectronic sequence

Abstract

Relativistic multiconfiguration Dirac - Fock (MCDF) transition energies and oscillator strengths are determined in an `optimal level' scheme for both the spin-allowed - and spin-forbidden 3 - transitions in the magnesium isoelectronic sequence through . The modest relativistic configuration mixing to represent the intravalence correlation is combined in MCDF calculations with a polarization model to account for valence - core electron correlation. For the first few members of the sequence (Mg I to Cl VI) rather extensive relativistic configuration interaction Dirac - Fock (CIDF) calculations (with and without core polarization) are also performed to improve the representation of the intravalence electron correlation which is important for the neutral end of the sequence. The influence of the intravalence correlation, as well as the valence - core electron correlation on oscillator strengths, excitation energies and ionization energies is investigated. The proper representation of the intravalence electron correlation is found to be crucial for oscillator strength calculations near the neutral end of the magnesium isoelectronic sequence. For some elements of the sequence the present data are the only ones available.

Absolute transition probabilities of Al I and Al II spectral lines and intensity ratios within multiplets

“…The agreement of experimental data is within a 2% limit and the average experimental value is also presented in Table 1. Radiative lifetimes of singlet and triplet 3p 1,3 P levels are calculated in a number of theoretical papers (Jonsson & FroeseFisher 1997;Zon & Froese-Fisher 2001;Stanek et al 1996;Chang & Fang 1995;Chou et al 1973;Das & Idrees 1990;Huang & Johanson 1985;Cowan et al 1982;Chang & Wang 1987;Hibbert & Keenan 1987;Laughlin & Victor 1979) some of them published recently. The agreement of theoretical data for the singlet 3p 1 P o 1 level is very good (within a 3% limit) and there is also good agreement between experimental and theoretical data for this level.…”

Atomic data and spectral line intensities for Ca IX

“…These calculations have been carried out by a number of authors using different techniques and atomic model (Fawcett [16], Kastner et al [17], Christensen et al [18], Tayal [19], Godefroid [20], Froese Fischer et al [21], Stanek et al [22], Zou & Froese Fischer [23], Tayal [24], Safronova et al [25], Aashamar [26], Karpuskiene et al [27]). Most of the calculations provided data only for levels in the n = 3 complex, but a few of them also included some n = 4 levels (Kastner et al [17], Christensen et al [18], Froese Fischer et al [21], Aashamar [26], Karpuskiene et al [27] and Tayal [24]).…”

Atomic data and spectral line intensities for Ni XVII

“…Laboratory measurements from many different devices provided line wavelengths [7][8][9][10][11][12][13][14][15] and level lifetimes [16][17][18][19]. A host of calculations have been performed to determine the radiative transition rates of an increasingly larger number of energy levels [20][21][22][23][24][25][26], but calculations of collisional excitation rates have been surprisingly scarce. Moreover, collision rates calculations were restricted to a small number of levels [27][28][29][30], so that the soft X-ray emission of many lines from the n = 3 complex as well as from the n = 4,5 configurations were not included.…”