Partial cross sections and angular-distribution asymmetry parameters were measured for subshell photoionization of xenon for photon energies between 40 and 1000 eV. These large-scale measurements show that the pronounced interchannel coupling between the valence and the 4d electrons persists beyond the 4d shape resonance in the subsequent Cooper-minimum region. Multielectron processes associated with 4d and 4p photoemission were measured directly for the first time over a broader energy range covering the near-threshold behavior up to the sudden limit. Comparing our experimental results with calculations based on the single-particle model shows that this theory, which fails to describe the intermediate energy range even qualitatively for the valence electrons, gives partial cross sections in reasonable agreement with experiment at higher photon energies, particularly beyond the 3d threshold. The same result is shown by the angular-distribution asymmetry parameter P, except for the photoionization of the "4p" subshell which resembles more the behavior of a 4d electron, corroborating the theoretical assumptions of core-hole fluctuations between these two subshells. In the shape resonance region the presented 4d partial cross sections are in reasonable agreement with theoretical results obtained recently by many-body perturbation theory.

Partial photoionization cross sections and angular-distribution asymmetry parameters were determined for Kr 3d photoemission using photon energies of 100 to 280 eV (to 800 eV for the asymmetry parameter). For the 3p subshell, the branching ratio relative to the 3d cross section and the asymmetry parameter were measured using energies of 280 to 800 eV. These results show good agreement with Hartree-Fock-theory predictions at all photon energies. The summed intensity of 4p~np satellites relative to the 3d main line was found to be approximately constant in the photon-energy range 180 -280 eV, and the average asymmetry parameter for these shake-up states showed a marked increase over the same energy range.

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