Pressure and temperature dependence of cuprous oxide nucleation on Cu(410)

We studied the oxidation of Cu(410) during thermal O-2 exposure using high-resolution electron energy-loss spectroscopy. Cu2O is identified by loss peaks at 19 and 79 meV. By monitoring the intensity of the latter, we find that Cu2O formation depends strongly on the surface temperature and on the O-2 pressure and is kinetically limited by the impinging O-2 flux. Thermally activated step roughening, leading to detachment of Cu adatoms from the step edge, acts as a source of mobile Cu atoms, allowing for subsequent nucleation of Cu2O patches.