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New radiative lifetime measurements using time-resolved laser-induced fluorescence are reported for the lowest six even-parity levels of Eu II. Branching fractions, measured from Fourier transform spectra, are combined with these lifetimes to determine atomic transition probabilities for the strongest blue-UV lines and additional yellow-red lines of Eu II. These results are compared with published data, and generally good agreement is found. Recommended hyperfine structure constants and isotopic shifts for these lines are also assembled from the literature and supplemented, as needed, using results from nonlinear least-squares fits of line profiles in Fourier transform spectra. These laboratory data are applied in a new determination of the solar Eu elemental abundance, yielding ⟨log10 ε(Eu)⟩ = 0.52 ± 0.01, with ±0.04 estimated for each of internal (scatter) and external (systematic) uncertainties. From analysis of the profiles of three Eu II lines, primarily λ4129, isotopic fractions of 151Eu and 153Eu are shown to be consistent with their values in meteoritic material.
Lawler et al. (Thu,) studied this question.