Relativistic atomic structure calculations for highly-charged Ni-like ions with applications to laser spectroscopy

Abstract The lowest excited states (3 d 9 4 s ) J = 3 , 2 of Ni-like ions are highly metastable and decay through high-order forbidden transitions to the ground state ( 3 d 10 ) J = 0 . Theoretical studies suggest that the magnetic-dipole (M1) transition (3 d 9 4 s ) J = 3 – ( 3 d 9 4 s ) J = 2 between the lowest excited states could be suitable for the visible and infrared laser spectroscopy. The available benchmarks for this transition are limited, and previous theoretical calculations exhibit larger deviations from experimental values. In this work, we present relativistic atomic structure calculations using the multi-configuration Dirac–Hartree–Fock method for Ni-like ions in the range Z = 54–100. The calculations presented here show a significant improvement in agreement with the observed M1 wavelengths compared to previous theoretical results, with deviations below 1% for nearly all available experimental data.