Inner-shell photodetachment from Se$^{-}$*

The photodetachment spectrum of Se$^{-}$ from 50 - 62 eV has been investigated using the merged ion-photon beam photodetachment technique. Se$^{- }$ions were produced in a Cs sputtered negative ion source (SNICS II) while the photons were produced by the undulator on the Advanced Light Source Ion-Photon Beamline 10.0.1. Se$^{+ }$and$^{ }$Se$^{++}$ ions formed by double and triple detachment were detected as a function of photon energy. Correlations in short-lived negative ion resonances formed by completely filling the valence 4$p $shell in Se$^{-}$ by photoexcitation of 3$d $electrons lead to three resonance structures. The resonances are observed in both the Se$^{+ }$and$^{ }$Se$^{++}$ decay channels bound by several eV below the 3$d$ detachment threshold near 54 eV.