Structure of the surface methoxy species on Cu{111}

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.