Structural analyses of the c(2 × 4)-N + 2O and the (2 × 1)-N phases on Rh(110) by low-energy electron diffraction

Abstract

The LEED analysis of the Rh(110)-(2 × 1)-N phase supports convincingly the RhN-added-row model revealing a RhN bond length of 1.91 ± 0.04 A ̊ . The atomic geometry of c(2 × 4)-N + 2O on Rh(110) reflects the structural elements found in the pure N and O phases: The type of the Rh(110) surface reconstruction is induced by the oxygen adsorption, and a missing-row reconstruction analogous to the Rh(110)-(2 × 2)p2mg-2O surface is observed. Oxygen occupies the threefold-coordinated fcc site along the densily-packed rows. Nitrogen, however, causes the O network of the Rh(110)-(2 × 2)p2mg-2O to rearrange in order to provide N-adsorption sites which are maximal apart from the surrounding O atoms and, in addition, retains the local chemisorption geometry as compared with the pure (2 × 1)-N phase. Both requirements are met by shifting every second O-zigzag chain along the [11̄0] direction by a substrate lattice vector and by adsorbing N in the long-bridge site at the bottom of the (1 × 2) troughs.