Evidence of Kl double-electron excitations in x-ray photoemission spectra of solids: the case ofMgO and MgF2

The observation of shake-up satellites assigned to simultaneous excitation of 1s and 2p Mg core electrons in magnesium oxide and fluoride is reported. The presence of well-defined features due to KL double-electron excitations in x-ray photoemission spectra of these solid-state systems is assessed. Possible multiplet splitting and effect of crystalline structures in double-electron line shapes are discussed. Reference to previous works in atomic and molecular systems is given. The relevance of this problem in x-ray-absorption spectroscopy data analysis is pointed out.