The first spectrum of ytterbium (Yb I)

Wavele ngths a nd estimated inl e nsities for 1 79 1 lines of neulral ylle rbium in the region 2 t SS to 31 308 A a re reporl ed. The Zeeman effect has bee n invesli gated for 249 of Ihese IlI1 es . Ana lys Is of Ihe data has resuhed 111 c lassifi ca li on of 787 lines as tra ns iti o ns be l wee n 102 e ve n a nd 77 odd leve ls . Eve n leve ls ha ve bee n ass igned to the eleclron co nfigurali ons 4/" 6s 2 (Ih e ground s late), 4f"I6sns, 4f"6slld, 4{' 3 6s 2 6f), 4{"6f)2, 4f"':Xl', and 4j'3':Xl6s6p, Odd leve ls have' bee n ass igned 10 4j"I6snp, 4f"16s ,if, a nd 4{' 3 Sd6s 2 . Man y odd le vels are s till unass ig ne d , bUI Ihe lIlajori ly undoubl edl y be lon g to Ihe configuration 4/"Sd'6s.