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

We have recorded LEED I-V spectra from the clean Cu(100), Cu(100)-(root 2 x 2 root 2)R45 degrees-O, Cu(100)-c(2 x 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 x 10(-4) mbar, exhibits a weak c(2 x 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 x 10(-4) mbar, results in a (root 2 x 2 root 2)R45 degrees LEED pattern with mostly oxygen remaining on the surface. Annealing this structure to similar to 780 K results in the disappearance of the (root 2 x 2 root 2)R45 degrees 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 Ert1 (following the decomposition of N2O 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.