Large electron correlation effects in the nondipole asymmetry parameters near photoionization thresholds

The nondipole corrections to the dipole approximation for the angular distribution of photoelectrons are calculated for Ar 3s subshell in the Hartree-Fock (HF) approximation for photoelectron energies ranging from threshold to 2 keV. The effects of electron correlation which are very important have been taken into account using the multiconfiguration HF approximation. It is found that near the threshold from 0 to 50 eV photoelectron energy, the nondipole parameters show oscillatory structure due to large electron correlation effects. The results are compared with existing theoretical and experimental data