Strong nondipole effect created by multielectron correlation in 5s photoionization of xenon

The angular distribution of the Xe 5s photoelectrons was measured in the 90–225 eV photon energy range using linearly polarized synchrotron radiation. The experimentally determined angular distribution parameters were compared with theoretical values obtained from calculations based on the random-phase approximation and the time-dependent density-functional theory. Experiment shows that the dipole (β) and nondipole (γ) parameters vary strongly as a function of the photon energy, in accordance with calculations that account for the interchannel coupling. Nondipole effects observed clearly in experiment confirm the role of multielectron correlation in describing the 5s photoionization of Xe far from the ionization threshold.