Simulated Photoemission Spectra of Hydroxylated MgO(100) at Elevated Temperatures

Density functional theory has been used to investigate photoemission O1s core-level shifts (CLS) of hydroxylated MgO(100). Rapid proton exchange at elevated temperatures (300 K) yields broad features in the simulated photoemission signal, in good agreement with experimental observations. The results provide further evidence that the stable structure of hydroxylated MgO(100) consists of a partly dissociated water monolayer. Analysis of the CLS for adsorbed hydroxyl groups at different coverage reveals a pronounced effect on hydrogen bonding to neighboring H2O molecules. The inclusion of exact exchange by use of the hybrid PBE0 functional leads to quantitatively similar results as the gradient corrected PBE functional.