[en] The energies for the ionized states of N₂, CO, O₂ and NO are obtained by using an ab initio full valence configuration interaction (FVCI) method with a minimal basis set. The intensities of the corresponding valence shell MgKα X-ray photoelectorn spectroscopy (MgKα-XPS) spectra are estimated with plane wave approximation and the satellite bands in the observed spectra are analyzed. The present FVCI results give a quite reasonable interpretation of the bands, both with regard to the positions and the relative intensities. New assignments are proposed for some bands of O₂ and NO. (orig.)