STM and FTIR studies of methoxy and acetate on Cu(110) surfaces resulting from reactions with methyl acetate and preadsorbed oxygen

We have used scanning tunneling microscopy (STM) and Fourier transform infrared spectroscopy (FTIR) to examine clean and oxygen-precovered Cu(110) surfaces that have been exposed to methyl acetate (CH3CO2CH3). Both clean and completely saturated (2×1)O surfaces are comparatively inert to methyl acetate exposure. Methyl acetate reacts on surfaces containing (2×1)O islands and areas of the clean surface resulting in the appearance of (5×2) structures. We propose that these (5×2) structures consist of equal numbers of methoxy (CH3O) and acetate molecules (CH3CO2). Over time, these (5×2) structures disappear from the surface due to the decomposition of the methoxy and the resultant formation of a mobile acetate species on this surface. We have performed STM experiments that support these interpretations.