Zeeman Effect Data and Preliminary Classification of the Spark Spectrum of Praseodymium—Pr II

Abstract

The Zeeman effect of praseodvmium has been studied at fields up to 95,000 oersteds over the range 2400 to 7100A. $g$ and $J$ values have been determined for 74 Pr II levels from resolved Zeeman patterns of 141 lines. With these data, together with new wave-length data from the M.I.T.-W.P.A. Wavelength Project which have been applied to the spectroscopic interval sorter and interval recorder, a quadratic term array has been set up which accounts for 312 lines. This array is consistent with King's temperature classification of the lines and with all previous hyperfine structure observations. It is self-consistent in $g$ values to an average deviation of 0.005 unit, and in wave numbers to an average deviation of 0.08 ${\mathrm{cm}}^{-1\mathrm{}}$. Previously published hyperfine structure measurements were found insufficiently precise to aid the classification, but were of value in its verification. The lowest term of Pr II is found to be $f^3\left({}_{}{}^4{}_{}{}^{}I_{}^{\mathrm{o}}{}_{}{}^{}\right)·s-{}_{}{}^5{}_{}{}^{}{I}^{\mathrm{o}}_4^{}{}_{}{}^{}$. Most of the strong lines showing hyperfine structure arise from the $f^{3}s$ configuration.