Darmstadt 2008 – scientific programme
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MO: Fachverband Molekülphysik
MO 15: Experimentelle Techniken
MO 15.2: Talk
Thursday, March 13, 2008, 11:15–11:30, 3G
Surface Enhanced Raman Scattering (SERS) on Lithographically Fabricated Nano-Structured Gold Surfaces — •Malte Sackmann, Torsten Balster, Veit Wagner, and Arnulf Materny — Jacobs University Bremen, Germany
Raman spectroscopy is an optical technique for the characterization of the unique vibrational properties of molecules and therefore is used for chemical analysis. Since the intensity of the inelastically scattered light is weak, this technique is limited to the measurement of higher analyte concentrations in the range of mMol. Surface-enhanced Raman scattering (SERS) provides a possibility to overcome this restriction. By measuring the Raman signal of the molecules in the vicinity of nano-structured surfaces the signal can be enhanced by a factor of 106 or more, and therefore concentrations below Mol are detectable.
In order to gain a better understanding of the enhancement mechanisms, we created reproducible, well defined gold dot arrays on a silicon surface via e-beam lithography. The parameters like dot size, thickness, and spacing were varied and the dependence of the enhancement factors on these parameters are investigated. In our contribution we discuss the results of these measurements. With crystal violet (CV) as analyte using the excitation wavelengths 514 and 671 nm enhancement factors up to three orders of magnitude are observed. The SERS substrates were more efficient for the red excitation wavelength by a factor of approx. 10. In our discussion special emphasis is put on the excitation of and coupling to the surface plasmons.