Berlin 2008 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 18: Poster Session I - MA 141/144 (Atomic Wires; Size-Selected Clusters; Nanostructures; Metal Substrates: Clean Surfaces+Adsorption of Organic / Bio Molecules+Solid-Liquid Interfaces+Adsorption of O and/or H; Surface or Interface Magnetism; Oxides and Insulators: Clean Surfaces)

O 18.66: Poster

Montag, 25. Februar 2008, 18:30–19:30, Poster F

SERS and single-molecule SERS in metallo-dielectric structures — •Manuel Rodrigues Gonçalves, André Siegel, and Othmar Marti — Ulm University, Institute of Experimental Physics, Albert-Einstein-Allee 11, D-89081 Ulm, Germany

Surface enhanced Raman scattering (SERS) refers to a technique to enhance the Raman scattering cross section of few molecules adsorbed on metallic surfaces, in order to achieve high enhanced spectra. Despite its success as a chemical identification technique at very low molecular concentrations, its main drawbacks are the extreme sensitivity to the electromagnetic enhancements of the metallic structures, the poor reproducibility, and the fabrication of structures with defined strong field enhancements at specific wavelengths.

Single-molecule SERS requires very high field enhancements, of the order of 10¹⁴. The Raman spectra of very few, or single molecules present a blinking behaviour. It is commonly accepted that the blinking is characteristic of the Raman spectra of single molecules, adsorbed at metallic clusters or structures with extreme enhancements.

We have fabricated metallo-dielectric structures suitable for SERS using colloidal crystals as templates. The fabrication of the structures is reproducible. FEM and FDTD calculations indicate that very high field enhancements can be expected. Experiments using a confocal Raman microscope find blinking SERS at the predicted locations. This is an indication of a low number of molecules in the detection volume.