Photodetachment Spectroscopy of Ce$^{-\ast }$*

The lanthanide series of negative ions provides interesting challenges and rich spectroscopic results for experiment and theory alike. A 12keV Ce$^{-}$ beam has been used in perpendicular arrangement with tunable radiation from an Nd:YAG pumped OPPO laser to perform laser photodetachment spectroscopy. The quantity of photodetached neutrals has been measured as a function of photon energy in order to determine the relative cross section for neutral production. Within the range 0.5eV -- 0.75eV, the spectrum exhibits five sharp peaks in addition to broad threshold behavior. The energies and widths of these resonances will be used to further explain the discrepancies between standing theoretical [1] and experimental [2] values for the electron affinity. \newline [1] S.M. O'Malley and D.R. Beck, \textit{PRA} \textbf{61}, 034501 (2000), \textbf{74}, 042509 (2006); X. Cao and M. Dolg,\textit{ PRA} \textbf{69}, 042508 (2004). \newline [2] V.T. Davis and J.S. Thompson, \textit{PRL} \textbf{88}, 073003 (2002).