Variation of 3s photoionization resonance structures in a serial atomic number species Ar, K, and Ca

Subvalence 3s-shell photoionization resonances of Ca were measured with monochromatized synchrotron radiation and photoion time-of-flight spectroscopy method. Charge resolved photoion yield spectra were obtained. Broad peak structures were found in the Ca+ spectrum and shallow window structures were found in the Ca2+ spectrum. We performed MCDF calculations to assign the resonance structures. The 3s-shell photoionization of Ar and K were also measured for comparison. A systematic increase was observed in Fano-Beutler parameter and in the resonance width along with the increase of atomic number from Z=18(Ar) to 20(Ca). We discuss also the spectral structures that could be of the 3p double-shake-up satellites, which are observed in the 3s photoionization region. (author)