  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.
