Surface-Enhanced Raman and Fluorescence Spectroscopy of Dye Molecules Deposited on Nanostructured Gold Surfaces

Abstract

Nanostructured gold surfaces were prepared over silicon and glass surfaces using evaporation and sputtering techniques, respectively. The surface enhanced Raman scattering (SERS) activity of these surfaces was investigated for dye molecules such as Methylene Blue and Rhodamine 6G using excitation wavelengths of 532 and 632.8 nm. Our results clearly emphasize that the SERS signal strongly depends on the nature of the surface and is further amplified under electronic resonance conditions. In addition, time-dependent spectral collection of the SERS and the surface-enhanced fluorescence (SEF) of Rhodamine 6G signals were obtained and showed similar behavior that could be fitted using a multiexponential model. This suggests a similar photobleaching mechanism for both SERS and SEF signals. We suggest that the study of molecules photostability under enhanced electromagnetic field should be extremely interesting for the further development of optical near-field spectroscopy.