Spectra of Doubly and Triply Ionized Ytterbium, Yb iii and Yb iv†

Abstract

The emission spectrum of ytterbium was photographed under varied conditions from 600 to 11 000 Å in order to obtain a complete description of the spectra of the doubly and triply ionized species. The main transition arrays of these species were identified, and where feasible, the analysis was carried through. All 41 energy levels, 28 odd and 13 even, belonging to the 4f¹⁴, 4f¹³ 5d, 4f¹³ 6s, 4f¹³ 6p, and 4f¹³ 7s configurations of Yb iii have been experimentally determined along with the appropriate quantum numbers. Eleven of 20 possible 4f¹³ 6d levels and their quantum numbers have also been determined. Many Yb iii levels are supported by intermediate coupling calculations. The ionization potential of Yb iii was determined to be 25.4±0.5 eV from the Rydberg formula. The two ²F 4f¹³ levels of Yb iv have been determined in addition to 20 of a possible 107 4f¹² 5d levels, of which a few are expected to be spurious.