Doubly excited states ofC−andO−

A study of doubly excited Feshbach states of the negative ions of carbon and oxygen has been performed using the method of configuration interaction. Dominant two-particle excitations considered include $2p^2\to 3s^2$, $3s3p$, $3p^2$, and $4s^2$ for both ${\mathrm{C}}^{-}$ and ${\mathrm{O}}^{-}$ systems. Four states of ${\mathrm{C}}^{-}$ and twelve states of ${\mathrm{O}}^{-}$ have been located. No experimental results are as yet available for ${\mathrm{C}}^{-}$. Six of the states of ${\mathrm{O}}^{-}$ reported here have been detected experimentally.