K-shell photoionization of Be-like Boron (B$^+$) Ions: Experiment and Theory

TL;DR

This study combines high-resolution experimental measurements and theoretical calculations to analyze the K-shell photoionization of Be-like boron ions, providing detailed resonance data and validating theoretical models.

Contribution

It presents the first high-resolution experimental data on K-shell photoionization of B$^+$ ions and compares results with advanced theoretical calculations, confirming the accuracy of the RMPS method.

Findings

Resonance energies and widths measured with high precision.

Experimental resonance strengths align with theoretical predictions.

Lifetimes of resonances determined with ~4% uncertainty.

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/$\Delta$E up to 8800 ($\Delta$E $\sim$ 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 % $\rm 1s^22s^2$ $^1S$ ground-state and 40 % $\rm 1s^22s2p$ $^3P^o$ metastable-state ions in the primary ion beam and confirmed by comparison with independent absolute photo-recombination heavy-ion storage-ring measurements with B$^{2+}$ ions using the principle of detailed balance. Experimental determination of the line width for the $\rm 1s2s^22p$ $^1$P$^{\rm o}$ resonance gives a value of 47 $\pm$ 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 $\rm 1s2s2p^2$ $^3$P, $^3$D resonances are 10.0 $\pm$ 2 meV and 32 $\pm$ 3meV, respectively, compared to RMPS theoretical estimates of 9 meV and 34 meV.