Structural model of the relaxed surface with the positions of three-fold symmetry axes labelled A, B and C. Each surface unit cell contains four six-fold coordinated indium atoms (blue), 12 five-fold coordinated indium atoms (green), 12 three-fold coordinated oxygen atoms (red) and 12 four-fold coordinated oxygen atoms below (shaded red). The four types of three-fold coordinated oxygen atom are labelled α, β, γ and δ
The acidity of single hydroxyl groups on a metal oxide surface has been determined for the first time using non-contact atomic force microscopy (AFM) and a hydroxyl-functionalised tip.
1 With the new setup, researchers in Austria, Germany and the Czech Republic were able to directly assess the proton affinity of individual sites by probing the strength of their hydrogen bonds with the tip. ‘The indium oxide surface we investigated has four different oxygen atoms with different reactivity, which means we can study the proton affinity of four oxygen atoms in one ex