Dresden 2014 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 46: Plasmonics and Nanooptics I
O 46.4: Vortrag
Mittwoch, 2. April 2014, 11:15–11:30, TRE Phy
Resonant surface-enhanced Raman scattering in nanoparticle dimer structures — •Matthias Hensen1, Ingo Heesemann2, Elina Oberlander3, Adelheid Godt2, Thomas Huser3, and Walter Pfeiffer1 — 1Molecular and Surface Physics, Department of Physics, Bielefeld University, 33615 Bielefeld, Germany — 2Organic Chemistry and Polymer Chemistry, Department of Chemistry, Bielefeld University, 33615 Bielefeld, Germany — 3Biomolecular Photonics Group, Department of Physics, Bielefeld University, 33615 Bielefeld, Germany
Surface-enhanced Raman scattering (SERS) benefits from the local field enhancement in the vicinity of plasmonic nanoantennas. We experimentally investigate rodlike acetyl-protected dithiol molecules that specifically link two gold nanoparticles with a diameter of 40 nm and gap dimensions of about 1 nm. Raman spectroscopy using excitation between 473 nm and 785 nm wavelength reveals a resonant enhancement of the linker molecule related Raman signals for excitation around 650 nm. This coincides with the gold dimer resonance, as predicted by FDTD calculations, and we conclude that the resonant excitation of gold-nanoparticle dimers enhances the Raman signal. Furthermore, based on a quantitative analysis of particle and aggregate concentrations we derive Raman enhancement factors in comparison to dithiol molecules in acetone. About 100 linker molecules in the gap of a nanoparticle dimer contribute to the signal and a Raman enhancement factor of about 106 is obtained for resonant excitation.