Regensburg 2010 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 16: Interfaces II

MM 16.2: Talk

Monday, March 22, 2010, 16:30–16:45, H5

Finite element calculations of surface enhancement in attenuated total reflection infrared spectroscopy — •Ganesh Vasan and Andreas Erbe — Max-Planck-Institut für Eisenforschung GmbH, Düsseldorf, Germany

Surface Enhanced Infrared Absorption Spectroscopy (SEIRAS) is an effective tool at studying organic molecules in contact with metal nanostructures. Roughness or tailored structures on metal surfaces give rise to surface enhancements in the absorption spectra. A finite-element based solver of the Maxwell equations was used to simulate full spectra of organic molecules in contact with spherical and cylindrical nanostructures in the Attenuated Total Reflection (ATR) geometry on silicon internal reflection elements. Surface enhancement factors are defined, as obtained through reference runs.

The simulated field images and the absorption spectra show enhancements in both isolated and periodic cases with the absorbance increasing with decreasing inter-particle spacing. The computations confirm the experimental evidence that closer particles yield larger enhancements. Effects due to particle size have also been analysed, where larger particles show larger enhancements. The field images suggest the enhancement is because the particles act as local cavities.