Absolute cross sections for photoionization of Xe$^{q+}$ ions (1 $\le$ q   $\le$ 5) at the 3d ionization threshold
  The photon-ion merged-beams technique has been employed at the new Photon-Ion spectrometer at PETRA III (PIPE) for measuring multiple photoionization of Xe$^{q+}$ (q=1-5) ions. Total ionization cross sections have been obtained on an absolute scale for the dominant ionization reactions of the type h\nu + Xe$^{q+}$ $\to$ Xe$^{r+}$ + (q-r) e$^-$ with product charge states q+2 $\le$ r $\le$ q+5. Prominent ionization features are observed in the photon-energy range 650-750 eV, which are associated with excitation or ionization of an inner-shell 3d electron. Single-configuration Dirac-Fock calculations agree quantitatively with the experimental cross sections for non-resonant photoabsorption, but fail to reproduce all details of the measured ionization resonance structures. 
S. Schippers (1), S. Ricz (1 and 8), T. Buhr (1 and 7), A. Borovik Jr.   (1), J. Hellhund (1), K. Holste (1), K. Huber (1), ...
physics.atom-ph