Island-Dissolution Phase Transition in a Chemisorbed Layer

Abstract

A phase transition has been observed in O chemisorbed on W(110) at low coverages, with a transition temperature ∼250°K lower than that observed for saturation coverage $\mathrm{W}\mathrm{}\left(110\right)p(2\mathrm{}\times 1)-\mathrm{O}$. This transition is interpreted in terms of two-dimensional dissolution of islands. A fit to lattice-gas models for both low and saturation coverage allows separate determination of the attractive and repulsive adatom-adatom interactions, and gives values of - 0.069 and 0.15 eV/atom, respectively.