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 Cl¹⁴⁺ and Ar¹⁵⁺ 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.