6p1/2,3/2np;J=0,1,2 autoionizing series in atomic barium

We have investigated the 6${\mathit{p}}_{1/2,3/2}$np; J=0, 1, and 2 doubly excited, autoionizing series in atomic barium, that is, nine of the ten series of the 6pnp configuration, for n between 10 and 28. Experimental results are analyzed from two complementary points of view. First, we have studied the energy-level structure within a given n multiplet. Second, we have performed simple multichannel-quantum-defect-theory analysis of the 6${\mathit{p}}_{1/2,3/2}$np;J series, for each J value. We find that the jk coupling scheme is the most appropriate for describing the resonance states in the long-range region.