Photoionization spectroscopy of even-parity autoionizing Rydberg states of argon: Experimental and theoretical investigation of Fano profiles and resonance widths

Using the 4s'[1/2](0) and 4s[3/2](2) metastable states of argon created in a plasma discharge we perform photoionization spectroscopy of even-parity autoionizing Ar(np(')) Rydberg states between the first and second ionization limits. Fitting the data to a sum of Fano-type or Shore-type profiles allows us to extract the widths and energies of the three overlapping resonance states [1/2](1), [3/2](1), and [3/2](2) in the 11p' manifold. We compare the experimental analysis of the 11p' multiplet to theoretical calculations which are based on the configuration interaction Pauli-Fock approach with core polarization. Agreement between the experimental and theoretical resonance parameters is good.