Zeeman effect and revised analysis of singly ionized rubidium (Rb ii)

Abstract

The spectrum of Rb ii has been observed in a sliding-spark discharge with the NBS 10.7-m normal-incidence vacuum spectrograph and in an electrodeless discharge with the NBS 10.7-m Eagle spectrograph in air. The Zeeman effect was observed from 2200 to 5200 Å with an electrodeless lamp in a magnetic field of 31 000 G. The analysis has confirmed all ten of the previously known levels of the 4p55p configuration. The 4p54d, 4p55s, 4p55d, and 4p56s configurations have been considerably revised and extended. Almost all levels of these configurations are now known, as well as those of 4p56d, 4p57s, and 4p54f, which were newly located. All configurations have been theoretically interpreted, with configuration interaction included. The energy parameters determined from a least-squares fit to the observed level values are compared with Hartree–Fock calculations. The ionization energy as derived from the 4p5ns series, n = 5, 6, 7, is 220 070±25 cm−1 (2.7.285±0.003 eV).