TENSOR LEED ANALYSIS OF THE CU(110)-(2 X 3)-N SURFACE-STRUCTURE

A tensor LEED analysis of the Cu(110)-(2 x 3)-N surface structure supports. a reconstruction model in which the topmost layer can be described as a pseudo-(100)-c(2 x 2)-N overlayer, with metal corrugation of about 0.52 angstrom in the reconstructed layer. Each N atom is nearly coplanar with the local plane formed by the four neighboring Cu atoms. Of the four N atoms per unit mesh, three also bond to Cu atoms in the layer below and are therefore five-coordinate. Two of the three five-coordinate sites result from appreciable lateral displacements toward each other of both N atoms and Cu atoms below in the topmost Cu(110) layer. Average N-Cu bond lengths for the five-coordinate sites (1.87 angstrom) agree well with prediction, while the bond lengths for the four-coordinate sites (1.85 angstrom) appear somewhat long. These different N sites are discussed in relation to a recent STM study, and results from this LEED analysis are contrasted with those from the previous LEED study, which supported a [001]-missing row reconstruction of the surface.