Regensburg 2007 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 44: Poster Session II (Semiconductors; Oxides and Insulators: Adsorption, Clean Surfaces, Epitaxy and Growth; Surface Chemical Reactions and Heterogeneous Catalysis; Surface or Interface Magnetism; Solid-Liquid Interfaces; Organic, Polymeric, Biomolecular Films; Particles and Clusters; Methods: Atomic and Electronic Structure; Time-resolved Spectroscopies)

O 44.10: Poster

Mittwoch, 28. März 2007, 17:00–19:30, Poster C

Coverage and temperature dependence of ordered thin pentacene films on Ag(111) investigated with SPA-LEED — •Annegret Hauschild and Moritz Sokolowski — Universität Bonn, Institut für Physikalische und Theoretische Chemie, Wegeler Str. 12, 53115 Bonn

Ultra thin films (1-15 monolayers) of the organic molecule pentacene (C22H14) were deposited with organic molecular beam epitaxy (OMBE) on the Ag(111) surface. Depending on coverage and deposition temperature, different highly ordered structures were found by spot profile low energy electron diffraction (SPA-LEED). For the sub-monolayer, no long range order has been observed. At low temperatures (LT), different to the well known room temperature (RT) phase [1], two further highly ordered structures could be observed in the monolayer. However, by growing multilayers at low temperatures, no change in the LEED patterns was recorded. The LEED spots become only more diffus, this indicates a cluster growth in the Stranski-Krastanov mode. These LT phases are meta stable. By warming up the sample to room temperature, a phase transition to the RT phase occurs.

[1] M. Eremtchenko et al., Phys. Rev. B 72, 1 (2005)