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O: Fachverband Oberflächenphysik

O 7: Plasmonics and Nanooptics I

O 7.3: Vortrag

Montag, 11. März 2013, 11:00–11:15, H31

Antenna enhanced sensing of surface phonon polaritons — •Frank Neubrech^1,2, Tadaaki Nagao³, and Annemarie Pucci¹ — ¹Kirchhoff Institute for Physics, University of Heidelberg, Heidelberg, Germany — ²4th Physics Institute and Research Center SCoPE, University of Stuttgart, Stuttgart, Germany — ³International Center for Materials Nanoarchitectnics, National Institute for Materials Science, Tsukuba, Japan

Excited resonantly, antenna-like nanostructures confine the electromagnetic radiation on the nanoscale and therefore enhance the electromagnetic field in their vicinity, which can be exploited for surface enhanced infrared spectroscopy. The only precondition is a good match between the fundamental resonant excitation of the nanoantenna and the vibrational signal of the adsorbate of interest. To demonstrate the influence of the vibrational signal strength on the signal enhancement we performed infrared spectroscopic measurements using Si wafers covered with SiO2 layers of different thickness. For thin layers we observe only a small change of the relative transmittance due to the SiO2 vibration. For thicker layers the coupling between the plasmonic excitation and the SiO2 surface phonon polariton becomes stronger and the relative transmission at the respective frequency increases. Layers with thickness larger than some tens of nanometers feature a transmission close to 100% at the SiO2 frequency.