Nanoscale oxidation of Cu(100): Oxide morphology and surface reactivity

• Published in: The Journal of chemical physics 2007-01, Vol.126 (3), p.034703-034703-7
• Main Authors: Lampimäki, M., Lahtonen, K., Hirsimäki, M., Valden, M.
• Format: Article
• Language: English
• ISSN: 0021-9606; 1089-7690
• DOI: 10.1063/1.2424932

Surface oxidation of Cu(100) in O 2 has been investigated in situ by x-ray photoelectron spectroscopy, x-ray induced Auger electron spectroscopy (XAES), and scanning tunneling microscopy (STM) as a function of surface temperature ( T S = 303 - 423 K ) and O 2 pressure ( p O 2 = 3.7 × 10 − 2 - 213 mbars ) . Morphology of the oxide on the surface and in the near surface layers is characterized by utilizing STM and the inelastic electron background of the XAES O K L L signal. Analysis of the peak shape of the XAES Cu L M M facilitates the quantification of Cu, Cu 2 O , and CuO surface concentrations. The authors conclude that the surface oxidation of Cu(100) proceeds in three distinct steps: (1) Dissociative adsorption of O 2 and the onset of Cu - ( 2 √ 2 × √ 2 ) R 45 ° - O ( θ O = 0.5 ML ) surface reconstruction, (2) initial formation of Cu 2 O and the appearance of 1.8 Å high elongated islands that also adopt the Cu - ( 2 √ 2 × √ 2 ) R 45 ° - O structure, and (3) formation of highly corrugated Cu-O islands which together with the surface reconstruction strongly enhance the reactivity of the surface towards further oxide formation. Both Cu 2 O and CuO formations are enhanced by increased surface temperature, but no pressure dependence can be seen.