Members of the 6$p_j$${\mathrm{nf}}_{j\mathcal{’}}$ autoionizing series in barium have been observed experimentally using multistep laser excitation. The recorded spectra exhibit extremely broad profiles for n values ranging from 7 to 30. We have fitted the spectra using an energy-independent multichannel quantum-defect theory model that reproduces the data reasonably well in spite of the fact that the full widths at half maximum of the excitation profiles are comparable in magnitude to the energy spacings between adjacent states. Experimental quantum defects and autoionization rates are presented along with the parameters determined from the theoretical fit.

• Received 5 September 1989

DOI:https://doi.org/10.1103/PhysRevA.41.316