Photoemission study of the translational energy induced oxidation processes on Cu(111)

Moritani, Kousuke; Okada, Michio; Sato, Seiichi; Goto, Seishiro; Kasai, Toshio; Yoshigoe, Akitaka; Teraoka, Yuden

doi:10.1116/1.1743254

Cited by 27 publications

(50 citation statements)

References 29 publications

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“…Synchrotron radiation (SR)-XPS experiments were performed with the surface reaction analysis apparatus (SUREAC 2000) constructed at BL23SU in SPring-8 in Japan. [2][3][4]14 The photon energy for recording XPS spectra was set to 1090 eV. The Cu(511) sample was cleaned by repeated cycles of 1-keV-Ar + sputtering and annealing at the surface temperature (T s ) of 870 K until no impurity was detected by SR-XPS.…”

Section: Methodsmentioning

confidence: 99%

“…However, despite extensive studies, the correlation between reactivity and properties of steps is still an open question. 1 Recently, some of us reported on hyperthermal O 2 molecular beam (HOMB) induced oxidation of Cu(100), 2 Cu(111), 3 and Cu(110) 4 at room temperature, RT. A collision-induced absorption (CIA) mechanism was proposed both for Cu(100) and Cu(111), while an additional mechanism involving mobile Cu adatoms was suggested to be active for Cu(110).…”

Section: Introductionmentioning

confidence: 99%

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The effect of step geometry in copper oxidation by hyperthermal O2 molecular beam: Cu(511) vs Cu(410)

Okada

Vattuone

Rocca

et al. 2012

The Journal of Chemical Physics

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Steps are known to be often the active sites for the dissociation of O(2) molecules and the nucleation sites of oxide films since they provide paths for subsurface migration and oxygen incorporation. In order to unravel the effect of their morphology on the oxidation of Cu surfaces, we present here a detailed investigation of the O(2) interaction with Cu(511) and compare it with previous results for Cu(410), a surface exhibiting terraces of similar size and geometry but different step morphology. As for Cu(410) we find, by x-ray photoemission spectroscopy performed with synchrotron radiation, that Cu(2)O formation gradually starts above half a monolayer oxygen coverage and that the ignition of oxidation can be lowered to room temperature by dosing O(2) via a supersonic molecular beam at hyperthermal energy. The oxidation rate for Cu(511) comes out to be lower than for Cu(410) at normal incidence, about the same when the O(2) molecules impinge towards the ascending step rise, but higher when they hit the surface along trajectories even slightly inclined towards the descending step rise. These findings can be rationalized by a collision induced absorption mechanism.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The effect of step geometry in copper oxidation by hyperthermal O2 molecular beam: Cu(511) vs Cu(410)

Okada

Vattuone

Rocca

et al. 2012

The Journal of Chemical Physics

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“…A recent attempt to improve the quality of these films consisted in the use of hyperthermal O 2 molecular beams (HOMB) to produce oxide at lower crystal temperature, to minimize contamination problems and to reduce film defectivity. M. Okada et al reported on SMB-induced oxidation at room temperature of Cu(100) [296], Cu(111) [297] and Cu(110) [298]. A collision-induced absorption (CIA) mechanism was proposed both for Cu (100) and Cu (111), while, for Cu (110), an additional mechanism involving mobile Cu adatoms should be operative.…”

Section: The Role Of Steps In Cu Oxide Formationmentioning

confidence: 97%

Bridging the structure gap: Chemistry of nanostructured surfaces at well-defined defects

Vattuone

Savio

Rocca

2008

Surface Science Reports

121

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“…The diffusion coefficients for in-plane diffusion are 3.5×10 -10 nm 2 /s at 160 K and 98 nm 2 /s at 300 K. The diffusion coefficients for diffusion into the subsurface are 2.2×10 -10 nm 2 /s at 160 K and 62 nm 2 /s at 300 K. Thus, once ferromagnetic oxygen adsorbed structures form, diffusion rarely occurs in the experimentally-used low temperature region below 160 K, which is considered to be required for 0.5 ML coverage. From the results of a hyperthermal O 2 molecular beam experiment involving oxidation of Cu(111) surfaces [28], it has been reported that the oxidation process strongly depends on the O 2 translational energy, surface temperature and surface diffusion. We must optimize these parameters to realize coverages higher than 0.4 ML.…”

Section: Discussionmentioning

confidence: 99%

Ferromagnetic nanostructures of oxygen on Ag(111)

Kunisada

Nakanishi

Diño

et al. 2012

J. Phys.: Conf. Ser.

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Abstract. First principles calculations were performed to investigate the robustness of oxygen adsorbed structures that show ferromagnetic properties. These ferromagnetic properties are induced by ferromagnetic superexchange interactions and Ruderman-Kittel-Kasuya-Yosida (RKKY) interactions. Such ferromagnetic oxygen adsorbed structures appear only in the case of coverages higher than 0.5 ML, because the ferromagnetic superexchange interactions and RKKY interactions are appreciable between O-O only for short distances. In this work, we focused on single oxygen atom diffusion parallel and perpendicular to Ag(111) surfaces. The in-plane diffusion could induce associative desorption, which reduces the oxygen coverage. On the other hand, diffusion to the subsurface could quench the magnetic moment. These diffusion paths have effective diffusion barriers of 0.78 eV. Thus, such diffusion rarely occurs in low temperature regions. IntroductionSurface magnetism has attracted a great deal of interest in basic science and application fields. From the viewpoint of basic science, singular behaviours of magnetic impurities [1][2][3][4][5][6][7][8] (and references therein) on surfaces have been investigated, and are caused by the two-dimensionality of the surface. In addition, understanding and controlling these singular behaviours are also very important for realizing high capacitance and robustness of magnetic devices. Moreover, studies suggested that surface magnetic states can be useful for controlling catalytic reactivity [9-13] in fuel cell electrodes. These studies show that the efficacy of surface magnetism extends from spintronics devices to energyrelated technologies. Design and control of magnetic surfaces are promising ways for developing new effective devices and catalysts.Recently, we reported metastable ferromagnetic states of the O/Ag(111) system [14,15] by potential energy surface (PES) studies on O 2 dissociative adsorption on Ag(111) surfaces, and suggested possibilities for controlling the surface magnetic properties in this system. The ferromagnetic oxygen adsorbed structures on Ag(111) surfaces are induced by the ferromagnetic superexchange interactions and Ruderman-Kittel-Kasuya-Yosida (RKKY) interactions. Such ferromagnetic oxygen adsorbed structures appear only in the case of coverages higher than 0.5 ML, because the ferromagnetic superexchange interactions and RKKY interactions are appreciable between O-O only for short distances. In this work, we investigated the robustness of ferromagnetic oxygen adsorbed structures on Ag(111) surfaces. Especially, we focused on oxygen atom diffusion parallel and perpendicular to Ag(111) surfaces in the case of 0.5 ML coverage. In-plane oxygen atom diffusion, which corresponds to oxygen atom motion parallel to Ag(111) surfaces, makes the distance between oxygen atoms shorter, which changes the stable oxygen adsorbed structures to unstable ones. Oxygen atom diffusion into the subsurface, which correspond to oxygen atom motion perpendicular to Ag(111) surfaces,

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Photoemission study of the translational energy induced oxidation processes on Cu(111)

Cited by 27 publications

References 29 publications

The effect of step geometry in copper oxidation by hyperthermal O2 molecular beam: Cu(511) vs Cu(410)

The effect of step geometry in copper oxidation by hyperthermal O2 molecular beam: Cu(511) vs Cu(410)

Bridging the structure gap: Chemistry of nanostructured surfaces at well-defined defects

Ferromagnetic nanostructures of oxygen on Ag(111)

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