Experimental and theoretical study of bound and quasibound states of Ce

• Published in: Physical review. A, Atomic, molecular, and optical physics Atomic, molecular, and optical physics, 2011-09, Vol.84 (3), Article 032514
• Main Authors: Walter, C. W., Gibson, N. D., Li, Y.-G., Matyas, D. J., Alton, R. M., Lou, S. E., Field, R. L., Hanstorp, D., Pan, Lin, Beck, Donald R.
• Format: Article
• Language: English
• Subjects: AFFINITY; ANIONS; Atom and Molecular Physics and Optics; Atom- och molekylfysik och optik; ATOMIC AND MOLECULAR PHYSICS; ATOMS; BOUND STATE; CERIUM; CROSS SECTIONS; ELECTRIC DIPOLES; EV RANGE; EXCITED STATES; FINE STRUCTURE; GROUND STATES; ION BEAMS; LASERS; PARITY; PEAKS; PHOTONS; QUASIBOUND STATE; RELATIVISTIC RANGE; RESONANCE; SPECTROSCOPY
• ISSN: 1050-2947; 1094-1622
• DOI: 10.1103/PhysRevA.84.032514

The negative ion of cerium is investigated experimentally with tunable infrared laser photodetachment spectroscopy and theoretically with relativistic configuration interaction in the continuum formalism. The relative cross section for neutral atom production is measured with a crossed ion-beam-laser-beam apparatus over the photon energy range of 0.54-0.75 eV. A rich resonance spectrum is revealed near the threshold with, at least, 12 peaks observed due to transitions from bound states of Ce{sup -} to either bound or quasibound excited states of the negative ion. Theoretical calculations of the photodetachment cross sections enable identification of the transitions responsible for the measured peaks. Two of the peaks are due to electric dipole-allowed bound-bound transitions in Ce{sup -}, making cerium only the second atomic negative ion that has been demonstrated to support multiple bound states of opposite parity. In addition, combining the experimental data with the theoretical analysis determines the electron affinity of cerium to be 0.628(10) eV and the fine structure splitting of the ground state of Ce{sup -} ({sup 4} H{sub 7/2}-{sup 4} H{sub 9/2}) to be 0.097 75(4) eV.