The structure of atomic nitrogen adsorbed on Fe(100)
b'Nitrogen atoms adsorbed on a Fe(100) surface cause the formation of an ordered c(2 \\xd7 2) overlayer with coverage 0.5. A structure analysis was performed by comparing experimental LEED I\\u2013V spectra with the results of multiple scattering model calculations. The N atoms were found to occupy fourfold hollow sites, with their plane 0.27 \\xc5 above the plane of the surface Fe atoms. In addition, nitrogen adsorption causes an expansion of the two topmost Fe layers by 10% (= 0.14 \\xc5). The minimum r-factor for this structure analysis is about 0.2 for a total of 16 beams. The resulting atomic arrangement is similar to that in the (002) plane of bulk Fe4N, thus supporting the view of a \\u201csurface nitride\\u201d and providing a consistent picture of the structural and bonding properties of this surface phase.'