R-matrix study of the 6dng, 6dni and 7sni J=6 autoionizing Rydberg series of barium

The 6dng, 6dni and 7sni J=6 autoionizing Rydberg series of barium have been investigated using the eigenchannel R-matrix method together with multichannel quantum defect theory. For the 6dng and 6dni J=6 series, results concern the energy positions, autoionization widths and autoionization branching ratios as well as the perturbations of these series by 4fnl J=6 e levels. For the 7sni series, results restricted to the energy positions. The theoretical results are compared with recent experimental results and show good agreement for the 6dng and 7sni series. A possible explanation for the discrepancies between theory and experiment for 6dni series is proposed.