Activated dissociation via a trapping precursor: O2/Cu(001)-(2√×√)-O

Abstract

Dissociative adsorption of O2 on Cu(001)-(2√×√)-O was shown to induce Cu2O epitaxial islands on the surface. The initial dissociative sticking probability of O2 on Cu(001)-(2√×√)-O scaled with the total translational energy of incident O2, suggesting that the interaction potential was highly corrugated. The sticking probability decreased with increasing translational energy of incidence and increased with increasing surface temperature. For lower translational energy of incident O2 (⩽130 meV), the velocity distribution of the scattered molecules was of nonshifted Maxwellian-type, indicating trapping desorption. The translational temperature of the trapping desorption was lower than the surface temperature and increased linearly with surface temperature, suggesting that there was no barrier for desorption. Neither thermal desorption experiments nor velocity distribution analysis of the trapping desorption showed any evidences of recombination desorption. These results were interpreted as an activated dissociation via a trapping precursor. The activation barrier for dissociation was estimated as 330 meV. The angular distribution of the trapping desorption was fitted well by cos2 θ, which was in contrast to the expectation of a cosine angular distribution based on the detailed balance arguments. The discrepancy may have been attributable to preferential consumption of the parallel momentum of the trapped O2 for dissociation and imbalance between adsorbing and desorbing O2 flux.

Adsorption and diffusion dynamics of atomic and molecular oxygen on reconstructed Cu(100)

“…There are several experimental studies concerning this subject, [2][3][4][5] but only a few theoretical studies, 6,7 especially those related to the adsorption dynamics in the case of the oxygen induced, ͑2 ͱ 2 ϫ ͱ 2͒R45°-O reconstruction of Cu͑100͒. This reconstruction is observed to occur as the oxygen concentration on the Cu͑100͒ surface exceeds 0.34 ML ͑monolayer͒, 8,9 and it is due to the long-range Coulomb interaction between the on-surface oxygen atoms.…”

Oxygen adsorption-induced nanostructures and island formation on Cu{100}: Bridging the gap between the formation of surface confined oxygen chemisorption layer and oxide formation

“…Cu͑100͒ is reactive towards O 2 dissociation, and adsorption of O 2 and oxide formation have been extensively investigated on it by a wide array of techniques: low-energy electron diffraction ͑LEED͒, 8 scanning tunneling microscopy ͑STM͒/LEED, 9-16 molecular beam surface scattering ͑MBSS͒/reflection highenergy electron diffraction ͑RHEED͒/Auger electron spectroscopy ͑AES͒/thermal desorption mass spectrometry ͑TDMS͒/LEED, 17,18 surface stress change by crystal curvature technique/density functional theory ͑DFT͒/LEED, 19 LEED multiple-scattering analysis, 20 time-resolved verylow-energy electron diffraction ͑VLEED͒, 21 spot profile analysis low-energy electron diffraction/helium diffraction ͑HED͒, 22 high-resolution electron energy-loss spectroscopy ͑HREELS͒/LEED/AES, 23 HREELS/x-ray photoelectron spectroscopy ͑XPS͒, [24][25][26] hyperthermal O 2 molecular beam ͑HOMB͒/XPS, 27,28 near edge x-ray absorption fine structure ͑NEXAFS͒, 29 normal-emission photoelectron diffraction/NEXAFS/LEED, 30 surface-extended x-ray absorption fine structure ͑SEXAFS͒, 31 angle-and temperaturedependent SEXAFS, 32 angle-dependent NEXAFS and SEXAFS/LEED/XPS/AES/TDMS, 33 surface x-ray diffraction, 34 in situ synchrotron x-ray scattering, 35 transmission electron microscopy ͑TEM͒, [36][37][38][39][40][41][42][43][44][45] analytical electron microscopy ͑AEM͒, 46,47 and ab initio calculations. [48][49][50][51][52]…”

External stress-induced chemical reactivity ofO2on Si(001)

“…An O 2 beam with a narrow distribution of kinetic energy was used in this experiment using a supersonic molecular-beam technique. 8 The O 2 beam at the sample position was 2.5 mm in diameter. The samples used were Si͑001͒ wafers ͑B-doped p-type, 1 -10 ⍀ cm, 8 ϫ 28ϫ 0.5 mm 3 ͒ miscut by Ͻ0.5°to the ͑001͒ plane along the ͓110͔ direction.…”