Abstract: The O_(1s) binding energy of MgO, CaO, SrO and BaO were determined by means of XPS. Prior to the determination,the samples were heated in the spectrometer at 400 ℃. The surface carbonates were partly decomposed and the O_(1s) spectra of lattice oxygen of the oxides were recorded. The O_(1s) binding energies of MgO, CaO and SrO determined by present work are lower than that reported in the literatures. A reasonable correlation between O_(1s) binding energies determined by present work and the partial charge on oxygen calculated by Sanderson for these alkaline earth oxides are found. The O_(1s) binding energy of BaO_2 determined by present work is 530.9 eV which is also lower than that reported in the literatures.

Key words: XPS, O_1s binding energy, Alkaline earth oxides, Barium peroxide