Preliminary Analysis of the First Spark Spectrum of Cerium—Ce II

By applying the spectral interval sorter and a newly designed interval recorder to new data obtained with the automatic recording spectrum comparator on the M.I.T.-W.P.A. wave-length program, a preliminary term array for Ce II has been set up in which 584 lines have been accounted for as transitions between 31 lower and 51 upper states. The term diagram is found to be the most complex yet observed for a three-electron spectrum. Both configurations $4f5d6s$ and 4f5d² appear to be low in Ce II, contrary to the analysis of Haspas. Most of the differences between observed wave numbers and those computed from the term array are less than 0.02 cm^-1, and 60 percent of the lines are found to be consistent to within 0.002A. Several of the term assignments have been checked with partially resolved Zeeman patterns recorded by King and Albertson, and the absolute J values have been determined by this means. An inclusive description of the spectra of the cerium atom is being undertaken in the range 10,000 to 1000A.