Reconstruction of Cu(111) Induced by a Hyperthermal Oxygen Molecular Beam

This paper reports a study on the surface reconstruction on Cu(111) induced by a hyperthermal oxygen molecular beam (HOMB) at room temperature (RT). HOMB incidence at translational energies ( E i ) ≥ 0.5 eV induced surface reconstruction to the | −1 3 2 2 | structure for an O coverage (Θ) ≥ 0.27 monolayer (ML). On the other hand, long-range-ordered structures were not formed even at Θ ≈ 0.4 ML for the backfilling of thermal O 2 at RT. No surface reconstruction was induced at E i ≤ 0.23 eV where the attainable Θ value was 0.27 ML for the O 2 exposures below 10 18 molecules/cm 2 . Translational energy above 0.5 eV is required for the dissociative adsorption of O 2 and the resulting surface reconstruction at Θ ≥ 0.27 ML. The O-1s XPS peak for HOMB incidence at RT was resolved into two components, 529.4 and 528.9 eV, at Θ ≥ 0.27 ML, which can be assigned to the O atoms occupying the three-fold hollow sites on unreconstructed Cu(111) and four-coordinated sites on the | −1 3 2 2 | structure, respectively. Annealing the | −1 3 2 2 | reconstructed surface at 620 K decreased Θ to ∼0.27 ML and induced the so-called “29” superstructure.