Seventh Spectrum of Lanthanum: La VII

The spectra of lanthanum ions were photographed in the 90Å–1220Å region on a 3-m normal incidence spectrograph at the Antigonish laboratory and a 10.7m grazing incidence spectrograph at the NIST laboratory. The source used in both laboratories was a triggered spark. The 5s 2 5p 3 –(5s5p 4 +5s 2 5p 2 5d+5s 2 5p 2 6s) transitions of La VII were analysed. All five levels of the ground state and 37 of 44 levels of the 5s5p 4 +5s 2 5p 2 5d+5s 2 5p 2 6s configurations have been established. 102 lines have been classified in the 307–1005Å region. Hartree–Fock (HFR) and Least-Squares-Fit (LSF) calculations were carried out to interpret the spectrum.