Multichannel quantum-defect analysis of the bound even-parity J=2 spectrum of neutral barium

Abstract

Extensive new data on the bound even-parity J=2 spectrum of Ba provide an excellent opportunity for the application of multichannel quantum-defect theory (MODT) to this spectrum. The parametrisation of the J=2 energy levels is successfully carried out using a nine-channel MQDT model involving four limits. The influence of large spin-orbit coupling effects and configuration interaction is analysed. The mutual interaction of the 6snd1D2 and 6snd3D2 Rydberg series as well as the perturbations of these by levels pertaining to the 5dns (n=7,8), 5dnd (n=6,7) and 6p2 configurations are clearly interpreted.