Extended analysis of three times ionized barium (Ba IV)

The fourth spectrum of barium (Ba IV) has been investigated with the aid of experimental recordings made on a 3-m normal incidence vacuum spectrograph at Antigonish laboratory (Canada) in the wavelength region 300-2080 Å using a triggered spark as an excitation source. The spectral analysis has been extended to include a new odd-parity configuration 5s25p46p. Previously reported levels of the ground configuration and the three lowest excited configurations (5s5p6, 5s25p45d and 5s25p46s) have been confirmed. All the J≥7/2 unknown levels of the 5s25p45d configuration and the (3P) 4P5/2 level of the 5s25p46s configuration have now been established through the identification of transitions from the levels of the 5s25p46p configuration, all of which have now been established. A configuration interaction Hartree-Fock calculation supports the analysis.