AVS 53rd International Symposium
    Nucleic Acids at Surfaces Topical Conference Monday Sessions
       Session DN-MoA

Paper DN-MoA7
Investigation of the Electronic Structure of Ribonucleic Acid Homo Polymer Electronic Structure, Ionization Energy and Charge Injection Barriers to Inorganic Materials

Monday, November 13, 2006, 4:00 pm, Room 2014

Session: Nucleic Acids at Surfaces II
Presenter: J.P. Magulick, University of South Florida
Authors: J.P. Magulick, University of South Florida
Y. Yi, University of South Florida
M.M. Beerbom, University of South Florida
R. Schlaf, University of South Florida
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We employed electrospray thin film deposition in concert with photoemission spectroscopy (PES) to investigate the electronic structure of ribonucleic acid (RNA) homo polymers, and their interfaces to inorganic materials such as highly oriented pyrolytic graphite (HOPG) and Au. In these measurements RNA homopolymers were injected directly from solution into a high vacuum chamber attached via in-situ transfer to a photoelectron sprectroscopy chamber. This enabled the preparation of clean RNA thin films in multi-step deposition sequences starting out at initial sub-monolayer thicknesses to investigate the details of interface formation. The final multi-layer thickness of the films gave insight into the bulk electronic structure. After each deposition step the samples were characterized with PES without breaking the vacuum. Our results indicate distinctly different ionization energies and charge injection barriers between purines and pyrimidines. Purine homopolymers have an ionization energy of about 6-7 eV while pyrimidine homopolymers exceed 8 eV. In order to further investigate these differences, we also investigated the electronic structure of the isolated backbone, and the individual nucleobases using the same experimental protocol. These results gave insight into the.