Identification of optical lines from Ca-like Br15+, Kr16+, Zr20+, and Rh25+ ions at an electron beam ion trap

The spectroscopic investigation of optical spectra of Ca-like Br15+, Kr16+, Zr20+, and Rh25+ ions at an electron beam ion trap was presented. In the region of 200-700 nm, ten spectral lines emitted from these ions were identified, eight of which were reported for the first time. The multiconfiguration Dirac-Hartree-Fock and relativistic configuration interaction methods were employed in the calculations of energy levels and transition rates, in which the Breit interaction and QED effects were taken into account, and the contributions of core-valence and core-core correlations were found to be essential. The present results showed a good agreement between the theory and the experiment in general. For four lines, the discrepancies between the calculated and measured wavelengths were larger than 1.5%, and our accurate experimental results could be reference data for further calculations.