Lifetime measurements in the triplet system of Mg I

Kwiatkowski, Maciej; Teppner, U.; Zimmermann, Peter

doi:10.1007/bf01435045

Cited by 20 publications

(14 citation statements)

References 15 publications

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“…The atomic structure of Mg i and technical limitations prevented us from deriving a conclusive value. However, the remeasured value leans towards the measurements by Kwiatkowski et al (1980) and our calculated value. Therefore, we adopted our theoretical lifetime value (9.63 ns) for the 4s 3 S 1 level.…”

Section: Results and Conclusionsupporting

confidence: 79%

“…of 4s 3 S 1 level to 11.5 ± 1.0 ns. Other experimental studies find the lifetime ranging from 5.8 ns to 14.8 ns (Berry et al 1970;Schaefer 1971;Andersen et al 1972;Havey et al 1977;Kwiatkowski et al 1980). Apparently, there is a large spread in the literature values and a 2 ns difference in lifetime corresponding to a 0.08 dex difference in log(g f ) values.…”

Section: Results and Conclusionmentioning

confidence: 92%

“…(1) Kurucz (2009) Kwiatkowski et al (1980); (4) Jönsson et al (1984); (5) ; (6) ; (7) Aldenius et al (2007). of 4s 3 S 1 level to 11.5 ± 1.0 ns.…”

Section: Results and Conclusionmentioning

confidence: 98%

“…In the cases where we used experimental lifetimes of Jönsson et al (1984), the uncertainties vary between 5% and 7%. For the theoretical lifetime uncertainties, we compared our theoretical values (to be described in the following section) with the experimental lifetimes available in the literature (Kwiatkowski et al 1980;Jönsson et al 1984;Aldenius et al 2007). Figure 2 shows the comparison of the experimental lifetime values with the theoretical lifetime values that we calculated.…”

Section: Uncertaintiesmentioning

confidence: 99%

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Experimental and theoretical oscillator strengths of Mg i for accurate abundance analysis

Rhodin

Hartman

Nilsson

et al. 2017

A&A

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Context. With the aid of stellar abundance analysis, it is possible to study the galactic formation and evolution. Magnesium is an important element to trace the α-element evolution in our Galaxy. For chemical abundance analysis, such as magnesium abundance, accurate and complete atomic data are essential. Inaccurate atomic data lead to uncertain abundances and prevent discrimination between different evolution models. Aims. We study the spectrum of neutral magnesium from laboratory measurements and theoretical calculations. Our aim is to improve the oscillator strengths ( f -values) of Mg i lines and to create a complete set of accurate atomic data, particularly for the near-IR region.Methods. We derived oscillator strengths by combining the experimental branching fractions with radiative lifetimes reported in the literature and computed in this work. A hollow cathode discharge lamp was used to produce free atoms in the plasma and a Fourier transform spectrometer recorded the intensity-calibrated high-resolution spectra. In addition, we performed theoretical calculations using the multiconfiguration Hartree-Fock program ATSP2K.Results. This project provides a set of experimental and theoretical oscillator strengths. We derived 34 experimental oscillator strengths. Except from the Mg i optical triplet lines (3p 3 P• 0,1,2 -4s 3 S 1 ), these oscillator strengths are measured for the first time. The theoretical oscillator strengths are in very good agreement with the experimental data and complement the missing transitions of the experimental data up to n = 7 from even and odd parity terms. We present an evaluated set of oscillator strengths, gf, with uncertainties as small as 5%. The new values of the Mg i optical triplet line (3p 3 P• 0,1,2 -4s 3 S 1 ) oscillator strength values are ∼0.08 dex larger than the previous measurements.

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Section: Results and Conclusionsupporting

confidence: 79%

Section: Results and Conclusionmentioning

confidence: 92%

“…(1) Kurucz (2009) Kwiatkowski et al (1980); (4) Jönsson et al (1984); (5) ; (6) ; (7) Aldenius et al (2007). of 4s 3 S 1 level to 11.5 ± 1.0 ns.…”

Section: Results and Conclusionmentioning

confidence: 98%

Section: Uncertaintiesmentioning

confidence: 99%

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Experimental and theoretical oscillator strengths of Mg i for accurate abundance analysis

Rhodin

Hartman

Nilsson

et al. 2017

A&A

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“…Remarkably, the XCCSD(S) results are close to 42 11.5 ± 1.0 29.0 ± 0.3 − 5.9 ± 0.4 Kwiatkowski(1980) 43 9.7 ± 0.6 − − 5.9 ± 0.4 Andersen(1972) 44 10.1 ± 0.8 − − 6.6 ± 0.5 Schaefer(1971) 39 14.8 ± 0.7 25.6 ± 2.1 − 11.3 ± 0.8 Ueda(1982) 45 9.9 ± 1.25 − − 5.93 Havey(1977) 46 9.7 ± 0.5 − − − Gratton(2003) 38 9. …”

Section: Comparison With the Available Theoretical And Experimentaunclassified

Transition moments between excited electronic states from the Hermitian formulation of the coupled cluster quadratic response function

Tucholska

Lesiuk

Moszyński

2017

The Journal of Chemical Physics

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We introduce a new method for the computation of the transition moments between the excited electronic states based on the expectation value formalism of the coupled cluster theory (XCC) [B. Jeziorski and R. Moszynski, Int. J. Quant. Chem. 48, 161 (1993)]. The working expressions of the new method solely employ the coupled cluster operator T and an auxiliary operator S that is expressed as a finite commutator expansion in terms of T and T † . In the approximation adopted in the present paper the cluster expansion is limited to single, double, and linear triple excitations.The computed dipole transition probabilities for the singlet-singlet and triplet-triplet transitions in alkali earth atoms agree well with the available theoretical and experimental data. In contrast to the existing coupled cluster response theory, the matrix elements obtained by using our approach satisfy the Hermitian symmetry even if the excitations in the cluster operator are truncated, but the operator S is exact. The Hermitian symmetry is slightly broken if the commutator series for the operator S are truncated. As a part of the numerical evidence for the new method, we report calculations of the transition moments between the excited triplet states which have not yet been reported in the literature within the coupled cluster theory. Slater-type basis sets constructed according to the correlation-consistency principle are used in our calculations.

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Lifetimes and oscillator strengths in the triplet system of ZnI

1980

Self Cite

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Selective laser excitation was used to measure the radiative lifetimes of the ZnI triplet states 4s n s 3S 1 (n = 5 -7) and 4s n d3D 3, 3D2 and 3D 1 (n = 4 -6). These states were excited from the metastable 4s4p3P states, which were collisionally populated in an atomic beam. The values are compared with the results of other experimental methods (beam-foil, pulsed electron excitation, Hanle effect) and with theoretical calculations. The corresponding oscillator strengths are discussed with respect to the astrophysical determination of the Zn photospheric abundance.In a recent paper [-1] Biemont and Godefroid have published extensive calculations of oscillator strengths for neutral zinc and its isoelectronic sequence. They have used the multiconfigurational Hartree-Fock (MCHF) programs of Froese-Fischer [-2,3] considering the two outer electrons as a twoelectron system outside a closed core and including pair correlations between these electrons. One reason for this theoretical study was the discrepancy of photospheric and meteoric abundance of zinc. With the new theoretical values of oscillator strengths of the relevant transitions in ZnI this discrepancy is now resolved [4]. It is therefore very interesting to check these theoretical oscillator strengths by new lifetime measurements, because experimental values of lifetimes in Zn I obtained by different experimental methods like the beam-foil method [5,6], the delayed coincidence method with pulsed electron excitation [-7] or the Hanle-effect method [-8, 9, 11] differ considerably. It is well known, that in the case of nonselective excitation methods like the beam-foil method or pulsed electron excitation, cascade effects can reduce the accuracy of the measurements, even if the decay curves are analysed with several decay constants to account for cascade effects. That is why we used selective laser excitation in our measurements. We have concentrated on tripled states starting from the metastable 4s4p3p-states (Fig. 1), which were collisionally excited by electron impact.

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Lifetime measurements in the triplet system of Mg I

Cited by 20 publications

References 15 publications

Experimental and theoretical oscillator strengths of Mg i for accurate abundance analysis

Experimental and theoretical oscillator strengths of Mg i for accurate abundance analysis

Transition moments between excited electronic states from the Hermitian formulation of the coupled cluster quadratic response function

Lifetimes and oscillator strengths in the triplet system of ZnI

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