Beam-laser lifetime measurements for low-lying quartet states in Fe ii

Guo, Bin; Ansbacher, W.; Pinnington, E. H.; Ji, Qing; Berends, R. W.

doi:10.1103/physreva.46.641

Cited by 39 publications

(29 citation statements)

References 5 publications

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“…It should be noted that the Kurucz calculations involve forbidden transitions, and hence the lifetimes include both the dipole allowed and forbidden transitions; however the latter contribution is expected to be small for most levels under consideration. Present lifetimes of the fine structure levels of z 6 P o agree well with the recent measured values of Hannaford et at (3992) and Guo et al (1992), whereas those of Schade et al (1988) …”

Section: Oscillator Strengthssupporting

confidence: 81%

Atomic data for opacity calculations: XX. Photoionization cross sections and oscillator strengths for Fe II

Nahar

Pradhan

1994

J. Phys. B: At. Mol. Opt. Phys.

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Abstract. Large scale ab initio calculations for the radiative data of Fe II have been carried out in the close coupling (cc) approbation employing the it-matrix method and a target state expansion consisting of 83 LS terms of Fe III. All bound states of Fe II with n ≤ 10 and l ≤ 7are considered. The results include 1301 bound states in LS coupling, oscillator strengths for 35 941 transitions among the bound LS states, and detailed photoionization cross sections for all bound states. Autoionizing resonances, as well as the coupling to excited core states, enhance the photoionization cross sections substantially. The calculations of oscillator strengths have been extended beyond the requirement of the Opacity Project to include a large number of fine structure transitions in Fe II, using an algebraic transformation of the LS coupled line strength and the observed energies. The present ƒ-values compare favourably with available experimental values and the calculations by Kurucz. However, the present results differ considerably from earlier 16-state R-matrix calculations and the new radiative data yield Rosseland mean opacities that are 50% higher. Some special features in the monochromatic opacity spectra of Fe II are also noted.

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Section: Oscillator Strengthssupporting

confidence: 81%

Atomic data for opacity calculations: XX. Photoionization cross sections and oscillator strengths for Fe II

Nahar

Pradhan

1994

J. Phys. B: At. Mol. Opt. Phys.

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“…Measurements of branching ratios of high quality have been published by Kroll & Kock (1987), Whaling (as included in the compilation by Fuhr, Martin & Wiese 1988 -also private communication), Heise & Kock (1990), and Pauls, Grevesse, & Huber (1990). Level lifetimes have been derived with accuracies in the range 0.02-0.14 ns by Biemont et al (1991), Guo et al (1992), and Schnabel, Kock & Holweger (1999) using laser-induced fluorescence. Available lifetimes have been compiled and combined in Table 3.…”

Section: Appendixmentioning

confidence: 99%

Signatures of Convection in the Spectrum of Procyon: Fundamental Parameters and Iron Abundance

Prieto

Asplund²,

López

et al. 2002

ApJ

170

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We have observed the spectrum of Procyon A (F5IV) from 4559 to 5780Å with a S/N of ∼ 10 3 and a resolving power of 2 × 10 5 . We have measured the line bisectors and relative line shifts of a large number of Fe I and Fe II lines, comparing them to those found in the Sun. A three-dimensional (3D) hydrodynamical model atmosphere has been computed and is tested against observations. The model reproduces in detail most of the features observed, although we identify some room for improvement. At all levels, the comparison of the 3D time-dependent calculations with the observed spectral lines shows a much better agreement than for classical homogeneous models, making it possible to refine previous estimates of the iron abundance, the projected rotational velocity, the limb-darkening, and the systemic velocity of the Procyon binary system. The difference between the iron abundance determined with the 3D model and its 1D counterpart is ∼ < 0.05 dex. We find consistency between the iron abundance derived from Fe I and Fe II lines, suggesting that departures from LTE in the formation of the studied lines are relatively small. The scatter in the iron abundance determined from different lines still exceeds the expectations from the uncertainties in the atomic data, pointing out that one or more components in the modeling can be refined further.

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“…As a means of verifying that the measurements are within the stated uncertainties, we perform periodic end-to-end tests of the experiment by measuring a set of well-known lifetimes. These cross-checks include lifetimes of Be i (Weiss 1995), Be ii (Yan et al 1998), and Fe ii (Guo et al 1992;Biémont et al 1991), covering the range 1. 8-8.8 ns.…”

Section: Radiative Lifetime Measurementsmentioning

confidence: 99%

Improved Laboratory Transition Probabilities for Smiiand Application to the Samarium Abundances of the Sun and Threer‐Process–rich, Metal‐poor Stars

Lawler

Hartog

Sneden

et al. 2006

ASTROPHYS J SUPPL S

121

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Radiative lifetimes, accurate to AE5%, have been measured for 212 odd-parity levels of Sm ii using laser-induced fluorescence. The lifetimes are combined with branching fractions measured using Fourier transform spectrometry to determine transition probabilities for more than 900 lines of Sm ii. This work is the largest scale laboratory study to date of Sm ii transition probabilities using modern methods. This improved data set has been used to determine a new solar photospheric Sm abundance, log ¼ 1:00 AE 0:03, from 26 lines. The spectra of three very metal-poor, neutroncapture-rich stars also have been analyzed, employing between 55 and 72 Sm ii lines per star. The abundance ratios of Sm relative to other rare earth elements in these stars are in agreement and are consistent with ratios expected from rapid neutron-capture nucleosynthesis (the r-process).

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Beam-laser lifetime measurements for low-lying quartet states in Fe ii

Cited by 39 publications

References 5 publications

Atomic data for opacity calculations: XX. Photoionization cross sections and oscillator strengths for Fe II

Atomic data for opacity calculations: XX. Photoionization cross sections and oscillator strengths for Fe II

Signatures of Convection in the Spectrum of Procyon: Fundamental Parameters and Iron Abundance

Improved Laboratory Transition Probabilities for Smiiand Application to the Samarium Abundances of the Sun and Threer‐Process–rich, Metal‐poor Stars

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