Abstract

Cerium spectra were recorded in the 100–1240-Å region by use of laser-produced plasma and triggered spark sources. An earlier analysis of Ce xi was almost completely revised. In the even-parity system we established 31 levels belonging to the $5s^2,$ $5p^2,$ $5s5d,$ $5s6s,$ $4f5p,$ and $4f^2$ configuration, of which 28 are new levels. In the odd-parity system we established 36 levels, 31 of them new, belonging to the $5s5p,$ $5p5d,$ $4f5s,$ $5s5f,$ and $5s6p$ configurations. The $4f^2$ and $4f5d$ configurations have been identified in the Cd i isoelectronic sequence for the first time to our knowledge. One hundred twenty-four lines have been classified in Ce xi. Hartree–Fock and least-squares-fitting calculations were carried out, and they represent the observed spectrum satisfactorily. The ionization potential of the Ce xi ion has been estimated to be $1 468 150\pm 100 {\mathrm{cm}}^{-1}$ $(181.99\pm 0.01 \mathrm{eV}).$

© 2001 Optical Society of America

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