The First Spectrum of Ytterbium (Yb i)

Wavelengths and estimated intensities for 1791 lines of neutral ytterbium in the region 2155 to 31 308 Å are reported. The Zeeman effect has been investigated for 249 of these lines. Analysis of the data has resulted in classification of 787 lines as transitions between 102 even and 77 odd levels. Even levels have been assigned to the electron configurations 4f ¹⁴6s ² (the ground state), 4f ¹⁴6sns, 4f ¹⁴6snd, 4f ¹³6s ²6p, 4f ¹⁴6p ², 4f ¹⁴5d ², and 4f ¹³5d6s6p. Odd levels have been assigned to 4f ¹⁴6snp, 4f ¹⁴6snf, and 4f ¹³5d6s ². Many odd levels are still unassigned, but the majority undoubtedly belong to the configuration 4f ¹³5d ²6s.