Dresden 2006 – wissenschaftliches Programm

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O: Oberflächenphysik

O 14: Poster session I (Adsorption, Epitaxy and growth, Phase transitions, Surface reactions, Organic films, Electronic structure, Methods) (sponsored by Omicron Nanotechnology GmbH)

O 14.23: Poster

Montag, 27. März 2006, 18:00–21:00, P2

Simulations of film growth on polymer substrates — •Roberto Rozas and Thomas Kraska — Physical Chemistry, University Cologne, Luxemburger Str. 116, D-50939 Köln, Germany.

The physical properties of thin films on surfaces are different from the properties of the corresponding bulk phase. The study of the growth mechanism and its effect on the properties such as the size, shape and orientation of the deposited grains on a surface is fundamental for the improvement of the quality of thin films required in the development of advanced materials involving nanometer-scale structures. By means of molecular dynamics simulations the growth mechanisms of argon clusters on polyethylene film surfaces is investigated. In this system the weak interactions between the polymer and argon can be approximate by means of Berthelot combination rules. The polymer is modelled by a united atom model. Films in the glass phase are put in contact with a previously equilibrated vapour phase consisting of 5000 argon atoms. A Nosé-Hoover thermostat is applied to the polymeric substrate while the vapour phase is simulated in the microcanonical ensemble. Different regions of the phase diagram of argon are simulated, that means, different degrees of saturation and supersaturation of the vapour phase. Outside the saturation curve for low dense, stable gas phases, the argon atoms adsorb on the polyethylene surface building short-life two-dimensional islands (adsorption). The formation of stable argon clusters on the surface is observed for supersaturated vapour phases (heterogeneous nucleation).