Nondipole parameters in angular distributions of electrons in photoionization of noble-gas atoms - art. no. 052506

The parameters that determine the nondipole (E1-E2) corrections to the phot oelectron angular distribution have been investigated for the s- and p-subs hells of the noble-gas atoms through comparing results calculated in the Ha rtree-Fock (HF) approximation and taking into account multielectron correla tions, using the random-phase approximation with exchange. Our results cove r the photoelectron energy range epsilon from the photoionization threshold s to 1.6 keV. We find the interesting result that near the photoionization thresholds these parameters are generally characterized by an oscillatory b ehavior as a function of epsilon, exclusive of the parameter for the He 1s subshell. These oscillations are sensitive to multielectron correlations, e xcept those of the Ar 3p subshell. This finding supports once more that the photoprocesses in these atomic subshells are of a collective character. We conclude that their correct description cannot be achieved within the fram ework of a one-electron approximation such as the HF approximation. Results are presented and discussed.