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O: Fachverband Oberflächenphysik

O 35: Poster Session I (Metal, semiconductor and oxide substrates: structure and adsorbates; Graphene)

O 35.21: Poster

Dienstag, 12. März 2013, 18:15–21:45, Poster B1

STM and X-ray spectroscopy study on the self-assembly and chemical behavior of orotic acid on close-packed coinage metal surfaces — •Sybille Fischer, Anthoula C. Papageorgiou, Joachim Reichert, Katharina Diller, Francesco Allegretti, Florian Klappenberger, and Johannes V. Barth — Physik Department E20, TU München, James- Franck-Straße, D-85748 Garching

Understanding the self-assembly of small biomolecules including the DNA/RNA bases and related molecules as well as their interaction with metal surfaces is an important step towards the creation of biofunctionalized interfaces. Orotic acid is an important molecule in the de-novo synthesis of pyrimidines which include the RNA bases uracil and cytosine. Here we report the results of a multitechnique study investigating the self-assembly and chemical behavior of orotic acid on the Ag(111) and Cu(111) surfaces by means of scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine-structure (NEXAFS). While the molecules assemble in two room-temperature stable structures on the silver surface, we can only find a metastable structure on the copper surface. The XPS study as a function of temperature gives insight in the chemical transformations of the molecule’s functional groups, which guide the self-assembly whereas NEXAFS allows us to conclude about the molecular orientation with respect to the surface. Our findings are discussed with reference to the physical and chemical behavior of the related molecule uracil on Ag and Cu.