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Measurements of absolute cross sections for the K-shell photoionization of B-like atomic nitrogen ions were carried out utilizing the ion–photon merged-beam technique at the SOLEIL synchrotron radiation facility in Saint-Aubin, France. High-resolution spectroscopy with E/ΔE ≈13,500 was the maximum resolution achieved. We have investigated two photon energy regions: 404–409 eV and 439–442 eV. Resonance peaks found in the experimental measured cross sections are compared with theoretical estimates from the multi-configuration Dirac–Fock, R-matrix and empirical methods, allowing identification of the strong 1s → 2p and the weaker 1s → 3p resonances in the observed K-shell spectra of this B-like nitrogen ion. [ABSTRACT FROM AUTHOR]

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 1s2s2p23P, 3D resonances are 10.0 ± 2 meV and 32 ± 3 meV, respectively, compared to RMPS theoretical estimates of 9 meV and 34 meV. [ABSTRACT FROM AUTHOR]