One hundred and eighty seven energy levels are reported in the spectra Zr V, Zr VII, Nb VIII, Mo IX, studied for the first time, and in the spectra Zr VII, Nb VII, VII, and Mo VII, VIII, thoroughly revised. All of the levels of the ground configurations 4pk (k = 6,5,4) of the ions concerned and a good part of levels belonging to the first excited 4d and 5s configurations are established. In the case of Zr v and Nb vi, three members of the Rydberg series 4p5ns (n = 5,6,7) and two of the 4p5nd (n = 4,5) have been found, thus leading to the derivation of the ionization limits: Zr v 657 600 cm-1, Nb VI 827 300 cm-1 and Mo viii 1 022 800 cm-1.
MIRZA SAID-UZ-ZAFAR CHAGHTAI, "Energy Levels of Zr V, VI, VII, Nb VI, VII, VIII, and Mo VII, VIII, IX," J. Opt. Soc. Am. 59, 969-969 (1969)