Autodetachment study of the electronic spectroscopy of FeO−

The anion FeO− was studied by autodetachment spectroscopy in a coaxial laser–ion beam photodetachment spectrometer. Transitions were observed between the ground electronic state of the ion and several excited electronic states near the electron detachment threshold. Rotational assignments were carried out for several bands, and the measured linewidths yielded autodetachment lifetimes as a function of rotational energy for these bands. The results indicate a 4Δ ground state of FeO−. The autodetachment lifetimes show that some of the excited electronic states are dipole bound, and that one weakly bound state may be a valence excited state.