The First Spark Spectrum of Palladium (Pd II)

An analysis of Pd II is given which differs completely from the previous one made by McLennan and Smith. The terms found include 4d²D(4d⁹); 5s⁴²F, ⁴²P, ²D, ²G(4d⁸5s); all the related triads from the structure 4d⁸5p; 6s⁴²F, ⁴P₃, ²G₅(4d⁸6s); and fragments of terms due to 4d⁸5d. Zeeman effects of the majority of the lines have been measured and approximate g-values found for the low and middle sets of terms. The g-values depart largely from Land\'e's values, as do also the term intervals. Evidence is given that the term predicted by theory, 5s²S(4d⁸5s), is present but it has not been fixed with respect to the other terms. The lowest term 4d²D gives lines in the vacuum region and was found by Mr. H. E. White, of Cornell University, from plates taken there. The ionization potential is calculated from the s⁴F terms as 19.8 volts from 4d⁹ to 4d⁸. As in other spectra of this type there is some indication in the limits of the component series that the Hund theory of limits is incorrect.