Metastable Autoionizing States in Sodiumlike Chlorine

We have observed metastable autoionizing states associated with partially stripped, highly excited chlorine ions. Charge-state-fraction, electron-energetic, and series-limit arguments indicate that these states are primarily associated with sodiumlike chlorine (Cl⁶⁺), but few energy-level calculations exist for firm identification. Prominent peaks occur in the electron spectrum at 90±{}3, 101±{}3, 138±{}3, and 182±{}3 eV. A long-lived component of the 182-eV peak has a lifetime {≥} 43 nsec.