Scanning tunnelling microscopy and low-energy-electron diffraction were used to study N adsorbed via ion bombardment on the (100) face of Ni. low-energy electron diffraction patterns indicate a (2 x 2)p4g structure formed on the surface. Bias dependent atomic resolution images enable the selective imaging of the N and Ni atoms. Images indicate that the N atoms sit in four-fold hollow sites with the positions of the Ni atoms in qualitative agreement with a model previously proposed on the basis of low-energy electron diffraction. Large area images show a variety of defect structures. Out-of-phase domain boundaries occurred along the [001] and [010] directions. One atomic layer deep depressions shaped like polygons and troughs occurred on the surface. These depression structures were most likely artefacts of the method of nitrogen deposition.

A Scanning Tunnelling Microscopy Study of the (2 x 2)p4g Nitrogen-Induced Surface Reconstruction on Ni(100). F.M.Leibsle: Surface Science, 1993, 297[1], 98-105