LEED and STM studies of structures formed by NO dissociation on Cu(100) surfaces

Abstract

We have recorded LEED I- V spectra from the clean Cu(100), Cu(100)-(√2 × 2√2)R45°-O, Cu(100)-c(2 × 2)N surfaces and Cu(100) surfaces exposed to NO at varying pressures. The dissociation of NO on the clean Cu(100) surface, at room temperature and at a pressure of 1.2 × 10 −4 mbar, exhibits a weak c(2 × 2) LEED pattern with similar amounts of both O and N present on the surface. By contrast, the dissociation of NO on the clean Cu(100) surface, at room temperature and at a pressure of 6 × 10 −4 mbar, results in a (√2 × 2√2)R45° LEED pattern with mostly oxygen remaining on the surface. Annealing this structure to ∼ 780 K results in the disappearance of the (√2 × 2√2)R45° pattern and the appearance of another LEED pattern indicating a two-domain hexagonal structure on the surface. A similar LEED pattern has been observed by Ertl (following the decomposition of N 2O on the clean Cu(100) surface at 800 K). Comparisons of the LEED I- V curves for all of these structures allows qualitative predictions to be made regarding their surface structures. Scanning tunneling microscopy has been used to test these predictions.