Molecularly resolved studies of the role of basicity in the reaction of amines with oxygen at a Cu(1 1 0) surface

The role of basicity in the surface reactions of amines has been investigated in an STM/XPS study of the oxidation of methylamine, ethylamine and 2,2,2-trifluoroethylamine at a Cu(1 1 0) surface. Methylamine and ethylamine are strongly basic molecules and for sub monolayer concentrations of oxygen form an amine/oxygen complex characterised by a (3 × 1) structure. The complex rapidly decomposes at room temperature to form water and an imide which desorbs via β-elimination. In contrast, 2,2,2-trifluoroethylamine has a relatively low basicity and its reactions with surface oxygen do not involve a stable intermediate.