The spectrum of lanthanum was photographed in the 80–1220-Å region. The 5s5p4f configuration in La IX was established for what is to the authors’ knowledge the first time in the In I isoelectronic sequence. Four levels belonging to the odd-parity system 5s2(5p + 4f) and twenty-seven levels belonging to the even-parity system 5s2(5d + 6s + 5g) + 5s5p2 +5s5p4f have been established. Two of the four odd-parity levels and twenty-five of the thirty-two even-parity levels are new. We carried out least-squares-fitting and relativistic Hartree–Fock calculations to show the strong configuration interaction effects in the even-configuration system. Forty-seven lines were classified in La IX, of which thirty-seven are new lines.
© 1998 Optical Society of America
[Optical Society of America ]
R. Gayasov and Y. N. Joshi, "Spectrum of La IX : an interesting example of configuration interaction," J. Opt. Soc. Am. B 15, 2614-2619 (1998)