Quantitative PEEM and Raman study of nanorough Au SERS-Active substrates for molecular sensing applications
Résumé
Surface-enhanced Raman Scattering (SERS) is a well-established surface-sensitive technique for detecting the presence of trace amounts of molecular analytes. While the impact of surface singularities on plasmonic materials has been widely studied, fabrication of cost-effective efficient SERS substrates remains a challenge. In this paper, we present the study of large area Au SERSactive substrates, elaborated by thermal evaporation deposition, by photoemission electron microscopy (PEEM), a high-resolution near-field mapping technique, to access the statistical properties of the hot spot distribution. We experimentally demonstrate that the near field PEEM and far field Raman statistical signatures of nanorough Au surfaces are quantitatively correlated when used for molecular sensing. The maximum of the SERS signal of thiophenol (TP) molecules diluted to 10-6 M is observed near the film percolation threshold for which the hot spot density is maximum. Finally, SERS measurements from solutions of thiophenol (TP), Crystal Violet (CV)
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