3d photoionization of Xe, Cs and Ba and the collapse of the 4f wavefunction

Total photoion yield spectra in the vicinity of the 3d thresholds of Xe, Cs and Ba are presented. These spectra were recorded with higher photon energ y resolution than previously reported. For xenon the new experimental data reveal additional structures. Employing Hartree-Fock calculations, the orig in of the prominent resonances is explained: for Xe and Cs the main absorpt ion features are caused by shape resonances above threshold, whereas for Ba it is revealed that the 4f orbital has finally collapsed and the sharp res onances are caused by discrete excitations into bound states.