Abstract
Absolute cross sections for the K-shell photoionization of Be-like boron ions were measured with the ion–photon merged-beams technique at the Advanced Light Source synchrotron radiation facility. High-resolution spectroscopy with E/ΔE up to 8800 (ΔE ∼ 22 meV) covered the energy ranges 193.7–194.7 eV and 209–215 eV. Lifetimes of the strongest resonances are determined with relative uncertainties down to approximately 4% for the broadest resonance. The measured resonance strengths are consistent with 60% 1s22s2 1S ground-state and 40% 1s22s2p 3Po metastable-state ions in the primary ion beam and confirmed by comparison with independent absolute photo-recombination heavy-ion storage-ring measurements with B2 + ions using the principle of detailed balance. Experimental determination of the line width for the 1s2s22p 1Po resonance gives a value of 47 ± 2 meV and compares favourably to a theoretical estimate of 47 meV from the R-matrix with pseudo-states (RMPS) method. The measured line widths of the 1s2s2p2 3P, 3D resonances are 10.0 ± 2 meV and 32 ± 3 meV, respectively, compared to RMPS theoretical estimates of 9 meV and 34 meV.
Highlights
Satellites such as Chandra and XMM-Newton are currently providing a wealth of xray spectra on many astronomical objects, but a serious lack of adequate atomic data, in the K-shell energy range, impedes the interpretation of these spectra
The results in figure 1 were convoluted at 22 meV and 152 meV, to highlight the prominent resonance features that can be observed in the cross sections
Theoretical resonance parameters were inferred from the natural cross sections
Summary
Satellites such as Chandra and XMM-Newton are currently providing a wealth of xray spectra on many astronomical objects, but a serious lack of adequate atomic data, in the K-shell energy range, impedes the interpretation of these spectra. The goal of the present experimental and theoretical investigation is to provide accurate values for photoionization cross sections, resonance energies, and natural linewidths resulting from the photoabsorption of EUV radiation near the K-edge of Belike boron. This new study completes the work started at the ALS on K-shell excitation of Li-like B2+ [22] and complements our previous experimental and theoretical study on PI focusing on the valence shell of B+ ions [33].
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