Poisoning and non-poisoning oxygen on Cu(410)

We have investigated ethene and oxygen co-adsorption on Cu(410) by high resolution electron energy loss spectroscopy. We find that these two species compete for the adsorption sites and that pre-exposure to oxygen affects ethene adsorption more or less strongly depending on oxygen coverage and the kind of occupied sites. The c(2 × 2) O overlayer is inert with respect to ethene adsorption, while when some oxygen is removed by thermally induced subsurface incorporation, ethene chemisorption is restored. The latter species also adsorbs on the disordered oxygen phase formed when O(2) is dosed at low crystal temperature. Contrary to the bare surface case, most of the ethene ends up in a π-bonded configuration. Dehydrogenation occurs, too, albeit as a minority channel. The so-produced carbon reacts already at low temperature with adsorbed oxygen to yield carbon monoxide, which desorbs around 190 K.