Soft x-ray appearance potential spectroscopy study of MgO (100) and α-Al2O3 (100) single crystals

Abstract

Soft x-ray appearance potential spectroscopy (SXAPS) measurements was used to measure on MgO (100) and α-Al2O3 (100) single crystals. Mg 1s, Al 1s, and O 1s SXAPS self-deconvoluted (SD) spectra were obtained. The features of the Mg 1s and O1s SD spectra are in fair agreement with those of the near-edge x-ray absorption fine structure spectra for an MgO thin film (3 ML) on Ag (100). This suggests that the SXAPS spectra reflect electronic states of the relaxed MgO (100) surface. The features of the Al 1s and O 1s SD spectra are in qualitative agreement with those of the electron energy-loss spectroscopy. The SXAPS SD spectra are discussed in terms of antibonding states and partial density of empty states obtained by theoretical calculations for MgO and α-Al2O3, respectively. The present result suggests that the “approximate dipole selection rule” is applicable to the SXAPS spectra of MgO and α-Al2O3, as well as 3d transition metal oxides.