Evidence for [1s2p]3p shake-up channels in compounds and oxides of third-period elements

X-ray photoemission spectra (XPS) of NaF, MgO, Al2O3, SiO2, InP, and NaH2PO4 collected using synchrotron radiation in the 1900-3400-eV energy range are reported. Accurate XPS spectra have been collected around the Na, Mg, Al, Si, and P 1s photoemission peaks including a region extending for a few hundred eV on the high-binding-energy side. Clear features associated with additional excitations of 2p electrons, more evident in low-Z elements, have been identified. The fine structure of these satellites, dominated by the lower-upper splitting, has been studied in different compounds as a function of the photon energy. Energy positions and splitting are consistent with theoretical predictions