The transformation of the (1 × 2) Rh (110) missing row non-equilibrium structure to the stable (1 × 1) structure has been studied by He atom scattering. The transformation is found to take place by the formation of islands of the (1 × 1) phase which are elongated in the [10] direction giving rise to a mesh of alternately up and down steps. A numerical simulation, based on an anisotropic classical 2D Ising model, is presented and shows that the experimental data can be interpreted as a spinodal decomposition of a lattice gas.
