HYPERFINE-STRUCTURE AND MULTICHANNEL QUANTUM DEFECT THEORY ANALYSIS OF THE 6 S N G RYDBERG SERIES OF BARIUM

High resolution laser-atomic-beam spectroscopy has been applied to study the hyperfine structure of the barium 6 sng Rydberg series for n=6-40. The singlet-triplet mixing of the two 6 sng J=4 series is deduced through a diagonalisation of the total Hamiltonian. Multichannel Quantum Defect Theory (MQDT) has been used to reproduce both experimental level energies of the 6 sng J=3,4 and 5 series and the extracted singlet-triplet mixing. The close-coupling channels of the 6 sng Rydberg series turn out to be nearly pure jj-coupled channels in contradistinction to lower l Rydberg series. Furthermore MQDT is used to analyse the observed isotope shifts and peak intensities of the 6 sng Rydberg series. © 1988 Springer-Verlag.