A model of bonding between oxygen and metal surfaces

A bond model for oxygen-metal chemisorption is derived from a variety of experimental observations by using the following principles: (i) the oxygen can interact with arbitrary elements B to form the general OB2 tetrahedral structure through two bonding orbitals and two lone-pair nonbonding orbitals; (ii) the atomic radii vary with the alteration of their atomic states and they also contract with the reduction of their coordination numbers. It is proposed that the oxygen interacts with metal atoms through two Goldschmidt-contraction ionic bonds and two lone-pair nonbonding states. It is interpreted that the atomic dislocation, electron localisation and the variation of energy states during reaction are the consequence of the surface bond forming. This model is able to provide an excellent simulation of the very-low-energy electron diffraction from the Cu(001)-O surface and improved understanding of the scanning tunnelling microscopy/spectroscopy observations. (C) 1997 Elsevier Science Ltd.