Darmstadt 2008 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 23: Experimentelle Techniken

MO 23.2: Poster

Donnerstag, 13. März 2008, 16:30–19:00, Poster C1

Optimization of Nano-Structured Surfaces for Surface-Enhanced Raman Scattering (SERS) — •Malte Sackmann, Torsten Balster, Veit Wagner, and Arnulf Materny — Jacobs University Bremen, Germany

Surface-enhanced Raman scattering (SERS) in the visible spectral region is typically observed for molecules in the vicinity of nano-structured metal surfaces. Here, rough metal surfaces, metal colloid solutions (Sol) as well as metal tips cause a strong enhancement of the Raman signal. In consequence SERS is a suitable spectroscopic technique for the measurement of very low analyte concentrations.

In order to perform experiments leading to a better understanding of the enhancement effect, reproducible SERS-active substrates are required. For this purpose, we have prepared surfaces with two-dimensional gold-dot arrays on silicon by means of e-beam lithography. Different substrates were produced as grating-like arrangement of gold nano dots. In order to find the optimum enhancement, spacing, size and shape as well as the thickness of the gold layers (dot height) were varied. Raman spectra were recorded using the excitation wavelengths 514 and 671 nm resulting in a signal enhancement of up to three orders of magnitude. The SERS substrates were more efficient for the red excitation wavelength by a factor of approx. 10.

In our contribution, results of these experiments are shown and the relationship between the structure parameters and the enhancement factors are discussed. An outlook evaluating possible applications in industry and analytics is given.