Exposures to the yttrium arc in silver, burned in the Bitter electromagnet at fields of 85,000 oersteds, yielded interpretable Zeeman effects of the first three spectra of yttrium—Yt I, Yt II, Yt III. Zeeman patterns arising from transitions between energy states of the doubly-ionized atom were observed in the range 2950–2360A. Landé g factors were calculated for the 4d, 5s, and 5p energy levels. Magnetic splitting of lines in the first spark spectrum of yttrium permitted the determination of g values for 59 of the 61 known energy levels. Zeeman effects of the arc lines of yttrium were observed for lines of high intensity only. Inclusion of data of B. E. Moore and of W. F. Meggers gave fairly complete information of the Zeeman effects of Yt I. Over-all g sums pertaining to the singly-ionized atom verify the g-sum rule exceptionally well in spite of large variations of individual g values from the theoretical Ls values. Term classifications were verified in the majority of cases.
J. RAND McNALLY, JR. and GEORGE R. HARRISON, "Zeeman Effects in the Arc, First Spark, and Second Spark Spectra of Yttrium," J. Opt. Soc. Am. 35, 584-594 (1945)