Status and Perspectives of Lifetime Measurements on Ions of Iron Group Elements

Multiply charged ions of iron dominate the EUV spectrum of the solar corona, but ions of other iron group elements are also present. A number of electric dipole and higher-multipole order transition rates in such ions have been measured over the years, mostly by beam-foil spectroscopy, in heavy-ion storage rings, and in various ion traps. The experiments relate mostly to three ranges of atomic lifetimes, i.e., picosecond lifetimes of 3p levels with spin-conserving E1 decays, multi-nanosecond lifetimes of levels with spin-changing (intercombination) E1 decays, and millisecond to multi-second lifetimes of 3p and 3d levels without any E1 decay channel. The state of the knowledge base is assessed, and the problems of further progress are outlined.