Modelling the butterfly:: (√3 x √7) ordering on fcc(111) surfaces

The adsorption of a bridge-bonded anion onto an fcc(I 11) surface is studied using kinetic Monte Carlo simulations. Different models with first neighbour shell exclusion and finite second neighbour shell lateral interactions are considered. All simulated voltammograms show one peak associated with anion adsorption in a disordered phase, and one peak related to a disorder-order transition in the adlayer. The disorder-order transition transforms the adlayer with a coverage of 0.18ML into a (root3 x root7) ordered structure with a coverage of 0.20ML. The shape of the adsorption isotherm and the simulated voltammogram is strongly influenced by attractive or repulsive lateral interactions, as well as by the sweep rate and the presence of steps in the surface. (C) 2004 Elsevier B.V. All rights reserved.