Photodetachment Cross Sections of Ce$^-$

The photodetachment cross section of Ce$^-$ on the energy range 0.57-0.75 eV has been calculated using the relativistic version of Configuration Interaction in the Continuum formalism by Fano [1] and Mies [2]. Our results are able to interpret all the features in the tunable infrared photodetachment spectroscopy on the same energy range [3,4]. These include two bound to bound transitions and eight transitions to low-lying resonance states. By matching the calculated plot for cross section to the neutral production signal from the experiment, the electron affinity of Ce$^-$ is further defined to be around 0.628 eV, which agrees with the measurement [3]. The binding energy of the first excited state of Ce$^-$ 4f5d$^2$6s$^2$ can also be reliably extracted. The details of the calculation and the identity of each feature will be presented in our poster at the conference.\\[4pt] [1] U. Fano, {\em Phys. Rev.} {\bf 124}, 1866 (1961).\\[0pt] [2] F. H. Mies, {\em Phys. Rev.} {\bf 175}, 164 (1968).\\[0pt] [3] C. W. Walter {\it et al}, {\em Phys. Rev. A} {\bf 76}, 052702 (2007).\\[0pt] [4] C. W. Walter, private communication.