Berlin 2012 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 35: Poster Session II (Polymeric biomolecular films; Nanostructures; Electronic structure; Spin-orbit interaction; Phase transitions; Surface chemical reactions; Heterogeneous catalysis; Particles and clusters; Surface magnetism; Electron and spin dynamics; Surface dynamics; Methods; Electronic structure theory; Functional molecules)

O 35.45: Poster

Dienstag, 27. März 2012, 18:15–21:45, Poster B

Phase behavior of chain molecules on surface: Monte Carlo simulation — •Pritam Kumar Jana and Andreas Heuer — Institute of Physical Chemistry, University of Muenster, Corrensstr. 28/30, Muenster, Germany

Self assembled monolayers of organic molecules on solid substrate build well defined surfaces, which can be structured efficiently on a nanometer scale. Self assembled monolayers are formed by organic molecules which spontaneously chemisorb on solid substrate [1,2], e.g. alkanethiolates attaching to gold surfaces with their sulfur head groups. We have studied an idealized model of chain molecules adsorbed on a flat substrate by means of extensive Monte Carlo Simulations. Our study focuses on phase transitions within a monolayer rather than on self aggregation. We model the molecules as rigid chains of Lennard-Jones spheres with one head group. As chain molecules are considered as rigid rod, all intra molecular degrees of freedom have been neglected. The Monte Carlo dynamics involves translational move in 3D space and rotational moves in 2D space. In the course of the simulation the concentration of chain molecules is increased with a fixed flux. We determine the phase diagram in dependence of the different energetic and structural parameters (e.g. chain length) of the model.

[1] A. Ulman, Chem.Rev., 96, 1533, 1996. [2] G. E. Poirier, Chem. Rev., 97, 117, 1997.