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 44.21: Poster

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

High-Resolution Photoemission Spectra of Cytosine, Thymine and Uracil — •Andrea Haug, Maria-Benedetta Casu, Heiko Peisert, and Thomas Chassé — Institut für Physikalische und Theoretische Chemie, Auf der Morgenstelle 8, D-72076 Tübingen

In the last decade, significant progress has been made in the use of DNA bases as molecules for electronic applications such as bioorganic field effect transistors and molecular nanowires. Questions arise to which extent they could improve the present status of molecular electronics. These questions can be answered by the investigation of their electronic structure, of their interfaces with metals, and of their growth modes as thin films. In this work we present our investigations on the electronic and molecular structure of the DNA and RNA bases cytosine, thymine and uracil by X-ray photoemission spectroscopy (XPS) and ultraviolet photoemission spectroscopy (UPS). The films were grown by organic molecular beam deposition on polycrystalline gold with different film thickness (between 0.2 and 10 nm and above 20 nm). After each step the sample surface was characterized in situ by monochromatized XPS (Al-Kalpha 1486.6 eV) and UPS (He I, 22.2 eV) under UHV conditions. We have investigated the stability of the bases upon evaporation, the growth mode, and the interface properties.