Infra-red Photodetachment of Lanthanide Anions

Lanthanide anions, including Lu$^{-}$ and Tb$^{-}$, have been investigated at 1030 nm using a crossed laser-ion beams Laser Photodetachment Electron Spectroscopy apparatus. In the case of Lu$^{-}$, the measured spectral variation of the asymmetry parameter is shown to be consistent with $p$-subshell photodetachment using the simplified model of Hanstrop $et. al$ [Phys. Rev. A 40, 670 (1989)]. The experimental results are shown to be in good agreement with the bound states predicted by Elliav $et. al$ [Phys. Rev. A 52, 291 (1995)] and are in excellent agreement with the more recent calculations O'Malley and Beck [Private Communication 2008]. Results of recent photodetachment experiments on Tb$^{-}$ are also presented. which extend previous measurements to lower photon energies.