Identification of M1 lines of Ca-like Ge12+ and Se14+ ions at electron beam ion traps

Abstract Optical emission lines within the 200–750 nm range of the Ca-like ions Ge12+ and Se14+ are measured using electron beam ion traps. Six previously unreported spectral lines emitted by these ions are obtained. The multiconfiguration Dirac-Hartree-Fock (MCDHF) methods are employed to calculate the energy levels and transition rates, accounting for Breit interaction, QED effects, and significant valence-valence, core-valence, and core-core correlations. By comparing with the theoretical calculations, three lines each for Ge12+ and Se14+ ions are successfully identified. Along the isoelectronic sequence of the Ca-like ions from Fe6+ to Kr16+, the transition energy scaling with nuclear charge Z is investigated.