Sixth spectrum of lanthanum (La VI): analysis of the , and configurations

The spectrum of lanthanum was photographed in the 300 - 1220 Å wavelength region on a 3 m normal incidence and a 10.7 m grazing incidence spectrograph using a triggered spark source. The - transitions of La VI were analysed. We have confirmed the earlier analysis of Reader of the - transitions. Of 52 possible levels of the three odd configurations 42 have been established. Six of the 10 unknown levels have and give no transitions to the ground-state configuration. One hundred and three lines have been classified in the La VI spectrum. The least-squares-fitted and relativistic Hartree - Fock calculations were carried out to interpret the observed spectrum.