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Understanding surface enhanced Raman spectroscopy using accurate nearfield-simulations of real substrates Surface enhanced Raman spectroscopy (SERS) is a powerful technique that uses metal nanostructures to enable the analysis of monolayers and even single molecules adsorbed on the metal surface. This is possible because of the strong enhancement of the electric nearfield close to suitable metal nanostructures. Therefore a detailed specification of the electric nearfields at every point on the substrates surface is crucial for the understanding of SERS. Our approach is based on atomic force microscopy (AFM) to precisely determine the geometry of the nanostructures. From the geometry the electric near fields were calculated by use of a home-made Matlab implementation of the discrete dipole approximation (DDA). The DDA was chosen because it relies on no assumptions other than the target geometry and the dielectric functions of the materials involved. |