Spectrum of Rb IV

The Rb IV spectrum emitted from a sliding-spark discharge has been observed in the wavelength range 4500-290 A. About 550 lines have been classified. From the observations 129 energy levels have been established in the 4s24p4, 4s4p5, 4s24p35s, 6s, 5p, 4d and 5d configurations. The observed level structure has been interpreted by means of Hartree-Fock calculations and parametric fits including, in particular, Rydberg-series configuration interaction. The ionization energy of Rb3+ is estimated to be 421000 ± 2000 cm-1.