On the signatures of oxygen vacancies in O1s core level shifts

Density functional theory calculations are used to investigate O1s surface core level shifts for MgO(100), ZnO(10 1 ¯ 0), In 2 O 3 (111) and CeO 2 (111). Shifts are calculated for the pristine surfaces together with surfaces containing oxygen vacancies and dissociated H 2 . Pristine surfaces show small negative shifts with respect to the bulk components and vacancies are found to have a minor effect on the O1s binding energies of neighboring oxygen atoms. OH-groups formed by H 2 dissociation yield binding energies shifted to higher energies as compared to the oxygen atoms in the bulk. The results stress the difficulties in assigning core-level shifts and suggest that assignments of shifts in O1s binding energies to neighboring oxygen vacancies for the explored oxides should be reconsidered.