Misfit dislocations and lattice parameters of adsorbed xenon and krypton monolayers on graphite

Abstract

Recent electron diffraction experiments have shown that there are both localised and unlocalised solid phases of Kr and Xe monolayers on graphite and have determined the lattice parameters of these layers to ~0.3% accuracy. A model of these layers is developed which includes the effects of misfit dislocations between the monolayer and the graphite. The misfit dislocations explain the epitaxial orientation of the unlocalised layer and account for the order of magnitude of diffraction intensities from this layer. Several forms of dislocation energy are examined and, for a suitable choice of parameters, the model can be made to agree well with experimental lattice parameters. The Sinanoglu-Pitzer (substrate-mediated) three-body energy is found to be significant, but to have a value 0.4 ± 0.2 of that originally proposed.