2s, 2p photodetachment from the He-(P-4(o)) negative ion within the Dyson equation method

The results of many-body calculations of the 2s, 2p He-((4)p) photodetachment cross section are presented. Many-electron correlations, in particular the polarization interaction between a photoelectron and atomic core electrons in both initial and final states, are taken into account within the Dyson equation method. The calculated binding energies for 2s and 2p electrons are found to be equal to 1.075 and 0.080 eV, respectively. The 2p photodetachment cross section agrees quite well with available experimental data and previous calculations. The 2s photodetachment cross section reveals the well known strong shape resonance just above the 2(3)P threshold, which is associated with a 1s(2)p(2) quasi-bound state, although the calculated peak value is less than the experimental one.