Absolute cross sections for photoionization of Xe super(q+) ions (1 [< or =, slant] q [< or =, slant] 5) at the 3d ionization threshold

The photon-ion merged-beams technique has been employed at the new Photon-Ion spectrometer at PETRA III for measuring multiple photoionization of Xe super(q+) (q = 1-5) ions. Total ionization cross sections have been obtained on an absolute scale for the dominant ionization reactions of the type hv + Xe super(q+) arrow right Xe super(r+) + (q - r) super(e-) with product charge states q + 2 [< or =, slant] r [< or =, slant] 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.