LEED crystallographic studies for the Cu(110)-(2 × 3)-N surface structure

Abstract

An initial multiple-scattering analysis of LEED intensities has been performed for the Cu(100)-type top-layer reconstructions. The best R-factor analysis supports neither simple N overlayer models nor models with Cu(100)-type top-layer reconstructions. The best correspondence between calculated and experimental intensities appears with models where every other 〈001〉 row is missing, similar to that observed for the Cu(110)-(2 × 1)-O surface. The favoured surface structure has N atoms chemisorbed on long-bridge sites such that chains of (Cu aNCu bNCu a) x create a surface analogous to the ideal Cu 3N(110) sur face, except that every third N atom is missing from the surface chains. There is evidence that lateral displacement of copper atoms from the ideal positions leads to two different NCu surface bond lengths with values near 1.83 and 1.90 Å. Each N atom also bonds to two Cu atoms in the second layer with equal bond lenghts of about 1.88 Å.