High‐resolution electron‐energy‐loss spectroscopy of hydroxyl groups at the surface of bulk insulating oxides

The capability of high‐resolution electron‐energy‐loss spectroscopy to study adsorbates at the surface of bulk insulating oxides has been applied to the cases of OH/MgO(100) and OH/α‐Al 2 O 3 (0001). On MgO(100), two types of OH have been identified, either bonded to surface Mg ions (A type) or due to proton adsorption on surface oxygen ions (B type). Dense OH adlayers on MgO(100) (5‐coordinate Mg) have been seen to correspond to ν OH (A) = 3690 cm −1 (ν OH > 3700 cm −1 being suggested to be related to defects and/or low coverages). On α‐Al 2 O 3 (0001), a sharp stretching band ν OH has been recorded at 3720 cm −1 and assigned to OH bonded (or bridge‐bonded) to Al in octahedral position.