Hyperfine-structure-resolved laser spectroscopy of many-electron highly charged ions

Abstract Hyperfine structures of highly charged ions (HCIs) are favourable spectroscopic targets for exploring fundamental physics along with nuclear properties. Recent proposals HCI atomic clocks highlight their importance, especially many-electron HCIs, and they have been theoretically investigated by refining atomic-structure calculations. However, developments in hyperfine spectroscopy HCIs not proceeded due to experimental difficulty. Here, we demonstrate hyperfine-structure-resolved laser an electron beam ion trap plasma, employing the magnetic-dipole transition 4 d 9 5 s state 127 I 7+ . Ion-state manipulation controlled collisions well-defined laboratory plasma enables laser-induced fluorescence trapped HCIs. The observed spectrum evaporatively cooled under low magnetic fields shows characteristic features reflecting structures. present demonstration using combined optical approaches provides a benchmark state-of-the-art calculations offers possibilities variety unexploited experiments.