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O: Fachverband Oberflächenphysik

O 81: Poster Focus Session: Molecular Nanostructures on Surfaces - New Concepts towards Complex Architectures

O 81.10: Poster

Mittwoch, 14. März 2018, 18:15–20:30, Poster A

Determination of critical cluster size, diffusion barrier and cohesion energy of PTCDA on Cu(001) — •Janina Felter, Jana Wolters, Markus Franke, Gerben van Straaten, Caroline Henneke, and Christian Kumpf — Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, 52425 Jülich, Germany Jülich Aachen Research Alliance (JARA) - Fundamentals of Future Information Technology, 52425 Jülich, Germany

Understanding the adsorption and growth mechanisms of large π-conjugated molecules on noble metals is a key issue for designing and optimizing organic electronic devices. Here, we report on the growth of PTCDA on Cu(001) studied in situ and in real time with Low-Energy Electron Microscopy (LEEM). By analysing island size distributions within the aggregation regime and applying methods developed for atomic nucleation on surfaces, we were able to determine the critical cluster size i for the formation of stable clusters for temperatures between 300 K and 390 K. We find different values (i = 1 and i = 3) for two different temperature regimes. This allows us to determine the diffusion barrier for individual molecules and, with the help of pair-potential calculations, the cohesion energy of a cluster of two molecules.