Spectra of Rb ii, Sr iii, Y iv, Zr v, Nb vi, and Mo vii in the Vacuum Ultraviolet

Abstract

The characteristic resonance-line spectrum in the Kr i isoelectronic sequence, consisting of the five transitions to the 4p^{6 1}S₀ ground state from levels with J = 1 in the 4p⁵4d and 5s configurations has been observed from Rb ii to Mo vii. The observations were made with sliding sparks, on the 10.6-m normal-incidence spectrograph at NBS and the 5-m grazing-incidence spectrograph in Lund. A number of transitions from higher levels of the type 4p⁵nd, 4p⁵ns, and 4s4p⁶5p were also observed. Isoelectronic comparisons are given for all observed levels. The ionization energies in electron volts are