Two-dimensional electronic structure of the adsorbate system N∕Cu(100): Photoelectron spectroscopy and one-step model calculations

In this paper, we present a detailed study of the electronic structure of the adsorbate system Cu(100)c(2×2)N by using angle-resolved ultraviolet photoelectron spectroscopy. The measured spectra reveal a variety of complex multipeak structures below the Fermi level. The adsorbate-derived states, which are of special interest, have been selected from the Cu-induced peaks by varying the polarization angle of the linear polarized light. The experimental analysis is supported by self-consistent electronic structure calculations within the density functional theory in order to determine the symmetry properties of the different adsorbate states. Due to the direct comparison with calculated photoemission spectra, a quantitative analysis of the surface geometry was possible. A structure model with outward relaxation of the first layer and twofold symmetry caused by combined rumpling of Cu and N atoms within this layer is favored by our investigation.