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O: Fachverband Oberflächenphysik

O 36: Poster Session II (Organic films and electronics, photoorganics; Nanostructures; Plasmonics and nanooptics, Surface chemical reactions and heterogeneous catalysis, Surface dynamics )

O 36.21: Poster

Dienstag, 12. März 2013, 18:15–21:45, Poster B2

Surface-enhanced infrared spectroscopy of CBP-molecules based on nanometer-sized gaps — •Christian Huck¹, Frank Neubrech^1,2, Andrea Toma³, David Gerbert¹, Thomas Härtling⁴, Enzo Di Fabrizio³, and Annemarie Pucci¹ — ¹Kirchhoff-Institute for Physics, Heidelberg University, Germany — ²4th Physics Institute and Research Center SCoPE, University of Stuttgart, Germany — ³Istituto Italiano di Tecnologia (IIT), Genova, Italy — ⁴Fraunhofer Institute for Non-Destructive Testing, Dresden, Germany

Infrared spectroscopy is well suited for label-free characterization of molecular species. One disadvantage of the IR-spectroscopy is the relative low IR cross-section of molecular vibrations. One possibility to overcome this limitation is the use of surface-enhanced IR spectroscopy (SEIRS), where metal nanoparticles are used to enhance the electromagnetic field in their vicinity. If the resonance frequency of such particles matches molecule-vibrations, the vibrational signal can be enhanced up to 5 orders of magnitude. Additional enhancement is theoretically predicted and can be achieved by exploiting the extraordinary field enhancement of two antennas interacting across a very small gap.

Individual nanoantenna dimers with gap sizes down to 4 nm were prepared by electron beam lithography and subsequent photochemical metal deposition. Afterwards the dimers were covered with a 5 nm layer of CBP acting as a near-field probe. Our experiments show an increasing vibrational signal enhancement for decreasing gap sizes demonstrating the additional enhancement induced by nanometer-sized gaps.