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. Cu 2 O is identified by loss peaks at 19 and 79 meV. By monitoring the intensity of the latter, we find that Cu 2 O 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 Cu 2 O patches.