Photoionization of heavy atomic ions and giant resonance

Although research of photoionization of ions is the useful method to investigate the electronic structure of many electrons atomic system, a few experiments are found. We measured 4d photoionization spectra of Ba+, Eu+ and Xeq+ (q=1-3) by both photo and ion beam device. 4d giant resonance peak was observed by all ions. Although q was increased, the position and width of giant resonance peak of Xeq+ were constant. It is new phenomenon which is not explained by collapse of 4f wave function on the basis of one electron approximation. To identify the obtained peak of Xeq+, we carried out calculation by Multi-Configuration Dirac-Fock (MCDF) method and compared with the experimental results. The strong discrete spectrum near 55 eV was identified with 4d-5p transition originated by hole of 5p orbital depend on ionization. (S.Y.)