Reactivity to sulphur of clean and pre-oxidised Cu(111) surfaces

SURFACE SCIENCE

卷:600

Article; Proceedings Paper

Wiame, F. ; Maurice, V. ; Marcus, P.

关键词: scanning tunneling microscopy;    Auger electron spectroscopy;    low energy electron diffraction;    chemisorption;    copper;    sulphur;    oxygen;   

DOI  :  10.1016/j.susc.2005.11.062

来源: Elsevier

【 摘 要 】

The reactivity of clean and pre-oxidised Cu(111) surfaces exposed to sulphur (H2S) has been studied at room temperature by Auger electron spectroscopy, low energy electron diffraction and scanning tunneling microscopy. On the clean surface, the sulphur-saturated surface structure is dominated by the vertical bar(4)(3) (1)(5)vertical bar or so-called zigzag superstructure. It is shown that a single orientation domain is favoured by the slight misorientation (similar to 2 degrees) of the surface with respect to the (111) plane. Scanning tunneling microscopy measurements also revealed two minority structures. Pre-oxidation (vertical bar(4)(3) (1)(8)vertical bar-O/Cu(111) structure) was performed by exposure to 1.5 x 10(4) L of O-2 at 300 degrees C. Under exposure to H2S (1 x 10(-7) mbar) at room temperature, the oxygen is totally substituted by sulphur. Once initiated, sulphur adsorption seems to propagate to cover the whole surface on the O-covered surface faster than on the clean Cu(111). At saturation by adsorbed sulphur, the surface is completely covered by the (root 7 x root 7)R19.1 superstructure of highest coverage. This enhanced uptake of sulphur is assigned to the surface reconstruction of the copper surface induced by the pre-oxidation, causing a stronger reactivity of the Cu atoms released by the decomposition of the oxide. (c) 2006 Elsevier B.V. All rights reserved.

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