Regensburg 2019 – scientific programme
Parts | Days | Selection | Search | Updates | Downloads | Help
O: Fachverband Oberflächenphysik
O 41: Poster Tuesday: Nanostructures
O 41.5: Poster
Tuesday, April 2, 2019, 18:00–20:00, Poster D
One-dimensional molecular chains of Quinacridone on Ag(100) and Cu(111): STM- and SPA-LEED-investigations — •Niklas Humberg1, Rémi Bretel2, Alexander Eslam1, and Moritz Sokolowski1 — 1Institut für Physikalische und Theoretische Chemie der Universität Bonn, Germany — 2University of Paris-Saclay, Institut des Sciences Moléculaires D’Orsay, France
One-dimensional molecular aggregates are of high interest because they often show specific and pronounced coupling effects for electronic excitations, e.g. in optical spectra. Here, we report a structural analysis of two such systems, quinacridone (QA) on Ag(100) and Cu(111), by STM and SPA-LEED.
On Ag(100) QA grows in parallel homochiral one-dimensional chains at room temperature (RT), forming a metastable structure. Within these chains the molecules are parallel and linked pairwise via two hydrogen bonds. The distance between neighboring chains varies with coverage. After annealing at 500 K, a two-dimensional commensurate heterochiral structure is formed. It consists of homochiral dimers forming periodically indented and closely packed chains.
On Cu(111), QA grows in similar fashion at RT. However, the structure shows more disorder than that on Ag(111). The majority of the chains are not straight and contain many kink-like defects. The high degree of disorder also becomes apparent in the SPA-LEED pattern. The observed spots smear out, yielding a highly symmetric diffraction pattern with many lines of varying intensities.