Nanostructured surfaces

Vapor-liquid equilibrium and surface diffusion in adsorbed copper monolayers on the (112) tungsten face
Loburets A.T.1, Zayika S.O.1
1 Poltava National Technical University named after Yuri Kondratyuk. 
Pershotravnevy Avenue, 24, Poltava-36004, Ukraine. 
E-mail: anatollob@gmail.com
The thermodynamic properties of the third copper monolayer in the region of the coexistence of two-dimensional liquid and gas phases, including the critical point of two-dimensional system, were studied. Concentration profiles of diffusion coefficients [1] and adsorption properties (the work function and adsorption heat) were used. With growing coverages in investigated monolayer, decrease of diffusion coefficients and increase of adsorption heat were found. It was previously shown that the diffusively formed concentration distributions can display the phase state of the film [2]. The heterogeneity zone on the concentration profiles formed during the diffusion process is distinguished by a high concentration gradient because of the strong difference in the values of the diffusion coefficients in the two phases. Desorption occurs mainly from the gas phase and is controlled by the diffusion of copper in the region of the heterogeneous state of the adsorbed film, that is, the arrival rate of substance in the zone of intense desorption. Obtained information allowed to construct a binodal for the vapor-liquid equilibrium of a two-dimensional copper film, to determine the critical temperature and the critical coverage and to calculate the enthalpy of two-dimensional evaporation of the condensed phase. The strong asymmetry of the binodal indicates significant differences in the nature of the lateral interaction of adatoms in coexisting phases [3].

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2. Naumovets A. G., Vedula Yu. S. Surface diffusion of adsorbates // Surf. Sci. Rep. – 1984. – № 7/8. – Р. 365–434.
3. Zaika S.A., Loburets A.T., Naumovets A.G. High-Temperature Surface Diffusion of Copper on the (112) Face of Tungsten under Condition of Film-Layer Growth of Adsorbed Film // The Proceedings of 1-st International conference “Nanomaterials: Applications & Properties (NAP-2011)”. – Alushta, 2011. – P. 218–221.