The electron affinity of cerium has been measured using laser photodetachment electron spectroscopy. The electron affinity of Ce(1G4) was determined to be 0.955 +/- 0.026 eV. The data also show that Ce- has at least two bound excited states with binding energies of 0.921 +/- 0.025 eV and 0.819 +/- 0.027 eV relative to the (1G4) ground state of the cerium atom. The present experimental measurements are compared to recent calculations of the energy levels of Ce-. Strong disagreement with the most recent theoretical atomic structure calculations highlights the complicated nature of this particular lanthanide.

The electron affinity (EA) of europium has been measured using laser photodetachment electron spectroscopy. The EA of Eu( 8 S 7/2 ) was determined to be 1.053 ± 0.025 eV. The data also show that Eu − has at least one bound excited state with binding energy of 0.864 ± 0.024 eV relative to the ground state of the europium atom. The experimental results are consistent with recent EA measurements of lanthanide atoms whose anions are predicted to have [Xe](4f n 6p) (where n is odd) configurations.

We have measured the total cross section for photodetachment of the Na- ion over the photon energy range 30-51 eV. Electron detachment leads predominantly to the production of Na+ ions in this energy range. The structures in the measured cross section are associated with correlated processes involving the detachment or excitation of a 2p core electron, processes which are often accompanied by the excitation of one or more valence electrons. The most prominent feature in the cross section is a strong resonance associated with the excitation of a 2p electron from the core and a 3s valence electron. As in previous experiments on double excitation of valence electrons, electron correlation is seen to play an important role in the dynamics of negative ions.

The electron affinity of thulium has been measured using laser photodetachment electron spectroscopy. The electron affinity of Tm(2 F 7/2) was determined to be 1.029Ϯ0.022 eV. The data also show that Tm Ϫ has at least one bound excited state with a binding energy of 0.979Ϯ0.017 eV relative to the ground state of the thulium atom. The present experimental measurements are compared to a recent calculation of the electronic structure of Tm Ϫ and a recent experimental investigation of Tm Ϫ .

Laser photodetachment electron spectroscopy (LPES) experiments have been performed at the Negative Ion Research Facility at the University of Nevada, Reno, using a crossed ion-laser beams apparatus to investigate the structure and dynamics of heavy atomic anions. A small ion accelerator is used to produce monoenergetic beams of negatively-charged atomic ions. Ejected electrons (photoelectrons), produced by the collision of the ions with linearly-polarized photons, are collected and their kinetic energy is measured with a hemispherical-sector electrostatic analyzer. The resultant photoelectron spectrum is used to determine the electron affinity (EA) of several of the lanthanides, while limits on the electron affinities for others are inferred. In addition, the angular asymmetry parameters and angular distribution patterns of photoelectrons created by laser photodetachment of several heavy atomic anions, as well as the spectral dependence of those angular distributions, have been determined. Electron affinities and photoelectron angular distribution asymmetry parameters can offer crucial information regarding the electronic structures of these heavy atomic anions, and represent key information for models of these complex systems.