Measurement of the Electron Affinity of Cerium

Abstract

The electron affinity of cerium has been measured using laser photodetachment electron spectroscopy. The electron affinity of $\mathrm{Ce}{(}^{1}{\mathrm{G}}_{4})$ was determined to be $0.955\ifmmode\pm\else\textpm\fi{}0.026\mathrm{eV}$. The data also show that ${\mathrm{Ce}}^{\ensuremath{-}}$ has at least two bound excited states with binding energies of $0.921\ifmmode\pm\else\textpm\fi{}0.025\mathrm{eV}$ and $0.819\ifmmode\pm\else\textpm\fi{}0.027\mathrm{eV}$ relative to the ${(}^{1}{\mathrm{G}}_{4})$ ground state of the cerium atom. The present experimental measurements are compared to recent calculations of the energy levels of ${\mathrm{Ce}}^{\ensuremath{-}}$. Strong disagreement with the most recent theoretical atomic structure calculations highlights the complicated nature of this particular lanthanide.