Spectrum of doubly ionized yttrium (Y iii)

Abstract

The spectrum of doubly ionized yttrium was observed from 600 to 9700 Å by means of plane- and concave-grating spectrographs at NBS. About 100 new lines were observed. From these measurements, 40 new energy levels were derived. The known level system (Rb i isoelectronic sequence, 4p6nl) now includes the series ns (n = 5–9), np (n = 5–9), nd (n = 4–8), nf (n = 4–10), ng (n = 5–8), and nh (n = 6–8). The nf series shows irregular fine-structure splittings, 4f having a negative splitting of about 3 cm−1. The ionization energy of Y iii was determined to be 165 540.5 ± 1.0 cm−1 (20.52457 ± 0.00012 eV). A reexamination of Kiess’s data for Zr iv in the light of the Y iii analysis yielded a revised value for the ionization energy of Zr iv of 277 550 ± 20 cm−1 (34.412 ± 0.003 eV).