Metastable Autoionizing States of Highly Excited Heavy Ions

We report the respective electronic energies [-5.658 ± 0.024 and -6.369 ± 0.033 keV] and electron emission lifetimes [0.91 ±0.04 and 0.66 ±0.04 nsec] of the longest-lived autoionizing quartet states of lithiumlike ${\mathrm{Cl}}^{14+}$ and ${\mathrm{Ar}}^{15+}$ ions, firmly establishing the energy and lifetime scaling with $Z$. We discuss observable relativistic corrections to non-relativistic variational energy calculations. Production of metastable states belonging to lower charge states is discussed, and it is concluded that many excited heavy ions should exhibit them.