Structural Properties of the Negative Calcium Ion:Binding Energies and Fine-Structure Splitting

Abstract

The binding energies of the ${4s}^{2}4p^{2}P$ ground state in ${\mathrm{Ca}}^{\ensuremath{-}}$ have been determined by means of state-selective photoionization of Ca atoms produced in s-wave photodetachment to be $24.55\ifmmode\pm\else\textpm\fi{}0.10$ meV for the $J\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1/2$ and $19.73\ifmmode\pm\else\textpm\fi{}0.10$ meV for the $J\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}3/2$ component. The sensitivity of the detection technique applied has also made it possible to disprove previous claims for the observation of a metastable ${4s4p}^{2}^{4}P$ state in ${\mathrm{Ca}}^{\ensuremath{-}}$.