We report on the first observation of resonance structure in the total cross section for the photodetachment of ${\mathrm{Li}}^{-}$. The structure arises from the autodetaching decay of doubly excited ${1P}^o$ states of ${\mathrm{Li}}^{-}$ that are bound with respect to the $3p$ state of the Li atom. Calculations have been performed for both ${\mathrm{Li}}^{-}$ and ${\mathrm{H}}^{-}$ to assist in the identification of these resonances. The lowest lying resonance is a symmetrically excited intrashell resonance. Higher lying asymmetrically excited intershell states are observed which converge on the Li( $3p$) limit.

• Received 5 January 1995

DOI:https://doi.org/10.1103/PhysRevLett.74.4795