The structure of the spectra of doubly and trebly ionized zirconium

Seventy-five per cent of the lines observed in the spark spectrum of zirconium have been classified as combinations between terms of the quartet and doublet systems of Zr II. The terms which have been found are in all cases those required theoretically for an atom with three outer electrons. All the terms, except one, which can possibly arise from configurations of the electrons when they occupy 4d, 5s, and 5p orbits have been found. Of the terms possible when one of the electrons removes to a bd or 6s orbit only a few have been found, of which some form Rydberg series with the low terms. In all, 10 pairs of series-forming terms have been detected with either 3 F, J G, or *D of Zr III as limit. The results given by these different series for the distance between a 4 Fij^, the lowest term of Zr II, and a 3 F 2 , the lowest term of Zr III, are very consistent, the mean value being 113,175 cm -1