Tunable Infrared Laser Photodetachment Spectroscopy of La$^{-}$*

The negative ion of lanthanum has been investigated using tunable infrared laser photodetachment spectroscopy. The relative cross section for neutral atom production was measured with a crossed laser beam-ion beam apparatus over selected photon energy ranges between 0.3 -- 0.5 eV. The photodetachment spectrum reveals several sharp peaks due to negative ion resonances. The energies and widths of the resonances were determined by fitting with Fano profiles. The results are compared with theoretical calculations on excited states of La$^{-}$ [1].\\[4pt] [1] S.M. O'Malley and D.R. Beck, \textit{Phys. Rev. A} \textbf{81}, 032503 (2010).