Dresden 2014 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 55: Focussed Session: Towards a Quantitative Understanding of Complex Adsorption Structures: Surface Science goes Organic I

O 55.5: Topical Talk

Mittwoch, 2. April 2014, 17:15–17:45, TRE Phy

Surface crystallography of organic layers — •Georg Held — Department of Chemistry, University of Reading, UK — Diamond Light Source, Harwell, UK

In supramolecular structures of organic molecules on surfaces chemical bonds are formed at different levels, from covalent to Van der Waals. Their interplay determines, both the surface geometry and the electronic structure of these overlayers and, hence, detailed structural characterisation can reveal important information about the balance of the interactions involved. Many organic layers have been well characterized at the molecular level, mostly using scanning probe microscopy and/or spectroscopic methods, but experimental crystallographic information about inter-atomic bonds (intra-molecular, inter-molecular and molecule-substrate) is rare. LEED-IV structural analysis, despite being one of the most powerful techniques for surface crystallography in general, is still facing a number of problems, when applied to organic layers. Current limitations are imposed by the available computer power for large unit cells but also by the size and quality of the experimental data set. We will discuss strategies for improving the data set and modifications to the standard analysis methods that are necessary to make full use of these improvements. The second part of the talk will concentrate on structures of organic layers, such as amino acids on Cu{110}, which have been determined by LEED, and discuss the implications in terms of chemical bond formation and molecular recognition at surfaces.