MICROSCOPIC PROCESSES ACCOMPANYING 2D CONDENSATION IN METALLIC SUBMONOLAYERS

A continuous space model of a submonolayer with non-additive lateral i nteractions is applied to a Monte Carlo simulation of two-dimensional (2D) condensation phenomena. The system of Cu/W(110) is chosen to repr esent metallic adsorbates with attractive interactions. Equilibrium pr operties of adlayer as a function of temperature at a constant concent ration of adatoms are analysed. Morphology and energetics of Cu submon olayers are studied by analysing island sizes, number of islands, and number of monomers as well as total and lateral configurational energy of the system. The simulations show that the 2D condensation strongly depends on the concentration of adatoms as a result of changes in the degree of association in a 2D imperfect gas. The obtained heat of 2D condensation is in agreement with experiment and has its maximal value at relatively low coverage. Several stages of condensation are distin guished and their evolution with coverage and temperature is discussed .