4d → 5p transitions in the EUV photoabsorption spectrum of BaIV, BaV and BaVI

The photoabsorption spectra of Ba IV-Ba VI have been recorded using the dual laser plasma technique. Discrete structure due to 4d -> 5p transitions has been observed in the 75-85 eV region and identified using Hartree-Fock with configuration interaction calculations. The excited states decay by autoionization involving ejection of 5s or 5p electrons and rates for the different processes and resulting linewidths were also calculated. From these calculations, synthetic spectra were produced and show excellent agreement with the experimental data.