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 (${\mathrm{Cl}}^{6+}$), 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.