K-Shell Photoionization of B-like Oxygen (O$^{3+}$) Ions: Experiment and Theory

TL;DR

This study combines high-resolution experimental measurements and multiple theoretical models to analyze the K-shell photoionization of B-like oxygen ions, identifying key resonances and their properties.

Contribution

It provides the first high-resolution experimental data for B-like oxygen ion photoionization and compares it with advanced theoretical calculations.

Findings

Identification of strong 1s → 2p resonances

Measurement of autoionisation widths and oscillator strengths

Comparison of experimental data with theoretical models

Abstract

Absolute cross sections for the {\it K}-shell photoionization of boron-like (B-like) O$^{3+}$ ions were measured by employing the ion-photon merged-beam technique at the SOLEIL synchrotron-radiation facility in Saint-Aubin, France. High-resolution spectroscopy with E/$\Delta$E $\approx$ 5000 ($\approx$ 110 meV, FWHM) was achieved with photon energy from 540 eV up to 600 eV. Several theoretical approaches, including R-Matrix, Multi-Configuration Dirac-Fock and Screening Constant by Unit Nuclear Charge were used to identify and characterize the strong 1s $\rightarrow$ 2p and the weaker 1s $\rightarrow$ 3p resonances observed in the {\it K}-shell spectra of this ion. The trend of the integrated oscillator strength and autoionisation width (natural line width) of the strong $\rm 1s \rightarrow 2p$ resonances along the first few ions of the B-like sequence is discussed.