Photoelectric effect in the super transition array model

In this work we present the super transition array (STA) approach for calculating the detailed photoelectric spectra under local thermodynamic equilibrium conditions. We define the bound-free STAs and obtain analytic expressions for their moments (total intensity, average energy, and variance). It is shown that the various STAs connected with aspecific photoelectron can be combined first, and then integration over the continuum is carried out only once. The various initial superconfigurations give rise to the structure of the photoelectric spectrum near the ionization edges. The details of this structure are gradually revealed by the convergence procedure inherent in the STA model. The efficiency of the method is discussed. Results of a few examples are given in comparison with the average atom method and with detailed term accounting in cases where this approach is possible.