Berlin 2018 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

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

O 81.8: Poster

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

One-dimensional molecular chains of Quinacridone on Ag(100) and Cu(111): STM- and SPA-LEED-investigations — •Niklas Humberg, Alexander Eslam, and Moritz Sokolowski — Institut für Physikalische und Theoretische Chemie der Universität Bonn, Wegelerstraße 12, 53115 Bonn, Germany

We report a structural analysis of Quinacridone (QA) on Ag(100) and Cu(111) by scanning tunneling microscopy (STM) and spot profile analysis low energy electron diffraction (SPA-LEED). On Ag(100) QA grows at room temperature in parallel homochiral one-dimensional chains, forming a metastable structure. Within these chains the molecules are closely packed and linked via hydrogen bonds. The distance between two neighboring chains varies with coverage. After annealing to 500 K a commensurate heterochiral structure is formed. It consists of homochiral dimers forming periodically idented chains. An oblique unit cell with cell parameters a = (14.3 ± 0.3) Å, b = (16.9 ± 0.3) Å and α = (112 ± 0.5)^∘ was found.

SPA-LEED patterns of QA on Cu(111) suggest the presence of more disorder. The observed spots smear out, creating a highly symmetric diffraction pattern containing many lines with varying intensities.