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SYSA: Symposium Tayloring Organic Interfaces: Molecular Structures and Applications

SYSA 5: Poster Session SYSA

SYSA 5.35: Poster

Dienstag, 26. Februar 2008, 14:30–20:00, Poster A

Thin-Film Properties of DNA und RNA Bases: A Combined Experimental and Theoretical Study — •Andrea Haug, Sabine Schweizer, Florian Latteyer, Maria Benedetta Casu, Heiko Peisert, Christian Ochsenfeld, and Thomas Chassé — Institut für Physik. und Theoret. Chemie, Universität Tübingen

In recent years significant progress has been made in the use of organic materials as building blocks of organic electronics. The research has also been expanded in the field of bioorganic materials like DNA/RNA bases and their derivatives. The bases show interesting electronic properties that make possible the use of these molecules, e.g. as organic layers in OFET [1]. The structures of the DNA/RNA bases cytosine, uracil, and thymine in thin films with a nominal film thickness of >20 nm were studied using photoemission (XPS, UPS) and FTIR spectroscopy. The bases were evaporated in situ from powder on gold foil. The experimental results indicate that cytosine is composed of two energetically close tautomeric forms, whereas uracil and thymine exist only in one tautomeric form. For complementing the results, relative energies of tautomeric forms of cytosine, uracil, and thymine were calculated using Hartree-Fock (HF), density functional theory, and post-HF methods. Furthermore, the assignment of XPS spectra is supported by simple model considerations employing Koopmans ionization energies and Mulliken net atomic charges. The bases were also investigated in various film thicknesses (0.1-10 nm) focussing on the interface properties base-gold. [1] G. Maruccio et al. Nano Lett. 2003, 3, 479

Funding by Ba-Wü, AZ 24-7532.23-21.18/1 is acknowledged.