RYDBERG ENERGY-LEVELS AND THEIR STRUCTURE IN THE RUTHENIUM ATOM

The Rydberg energy levels and their structure in the Ru atom for the 4d7(4F)ns (n=28-50) and 4d7(4F)nd (n=24-56) series were measured by means of the laser resonance excitation-electric field ionization method. The Rydberg energy levels and relevant quantum defects are calculated using the relativistic self-consistent-field method. The calculated quantum defect values for the s and d series are: mu s=3.5, mu d=1.9. The relative line strengths within the multiplet of an electron configuration are also calculated. All the theoretical results are consistent with the experiments and the spectral terms of the measured lines can be identified. This is the first work to measure and analyse the level structure of Rydberg states of a platinum group atom. The first ionization potential of Ru is obtained by a non-linear fitting program as 59 365.9 (4) cm−1. This result is a significant improvement over that obtained by Callender et al. (1985). © 1990 IOP Publishing Ltd.