Hannover 2016 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 8: Experimental Techniques

MO 8.5: Vortrag

Dienstag, 1. März 2016, 12:00–12:15, f142

Investigation of the chemical enhancement contribution to SERS using a Kretschmann arrangement — •Faezeh Mohaghegh, Alireza Mazaheri Tehrani, and Arnulf Materny — Physics and Earth Sciences, Jacobs University Bremen, Campus Ring 1, 28759 Bremen

The fundamental enhancement mechanisms of SERS are the so-called electromagnetic enhancement (EM) caused by surface plasmon polaritons (SPPs) and a chemical enhancement (CE) resulting from the change of the molecule’ electronic structure when adsorbed on the metal surface.

In our work, we use a Kretschmann arrangement (KC), which allows for the study of the SERS effect using reproducible flat metal surfaces as SERS substrates. Dye molecules are used as adsorbates. The experiment has been optimized to achieve reproducible conditions. Within the experiment a decaying behavior of the Raman line intensities has been observed and analyzed. SERS spectra were obtained excluding the contribution of this deactivation process for different angles of incidence of the exciting laser beam. The Raman deactivation rate was found to be different for different vibrational modes where high-energy vibrations showed slower decay than the group of low-energy modes. The variation of the surface plasmon excitation in the thin silver film coated onto the prism surface of the KC resulted in drastically different relative enhancements of the different Raman modes pointing to a dominating contribution of the chemical enhancement mechanism in the single-layer SERS experiment.