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 4p6 1S0 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 Rb ii 27.285Y iv 60.60Nb vi 102.06Sr iii 42.87Zr v 80.36Mo vii 125.66.Anomalous relative intensities observed for the 4p54d transitions are found to be caused by excitation conditions within the light source.