Structure of the surface methoxy species on Cu{111}

Abstract

Angle-resolved photoemission spectroscopy has been used to identify four adsorbate-induced features from the surface methoxy species on Cu{111}. In agreement with IR data, the application of dipole selection rules suggests that the O–C axis is oriented perpendicular to the surface. The ordering of the 5a₁ and 1e emission bands is reversed compared with the methoxy species adsorbed on the Cu{100} and Cu{110} surfaces. The interpretation of the X-ray absorption data is more difficult, owing to the occurrence of overlapping resonances. A clear polarisation dependence is observed at the oxygen edge, but indicates that the O–C axis could be tilted by up to 30° from the surface normal. This apparent conflict with the photoemission data is attributed to the somewhat arbitrary nature of the standard curve-fitting procedures.