Adsorption sites and surface vibrations of the Cu(110)-(2×3)-N surface

High-resolution electron energy-loss spectroscopy has been used to determine the bonding geometry of N at the Cu(110)-(2×3)-N surface. Symmetry arguments coupled with lattice-dynamical calculations identify 11 of the 20 observed vibrational features as arising from N bound in the three inequivalent hollow sites of the surface. Seven of the high-energy, nondipole losses observed are attributed to N or ${\mathrm{N}}_2$ species in subsurface sites. Total-energy calculations suggest that subsurface N stabilizes the large rumpling of the Cu surface layer, which characterizes recently proposed structural models. © 1996 The American Physical Society.