Spectral dependence of the amplification factor in surface enhanced Raman scattering

Surface Enhanced Raman Scattering (SERS) is characterized by a strong signal amplification (up to 108–10) when both the excitation and the Raman photons frequencies match the localized plasmon resonances (LSPR) of the nanoparticles (NPs). In order to understand if the effective LSPR profile refers to the bare NPs or to the resonance of NPs “dressed” with the probe molecules, we perform multiwavelength (514 nm, 633 nm and 785 nm) SERS experiments using both evaporate gold NPs and gold Nanoantennas produced by electron beam lithography (EBL) as SERS-active substrate on which we deposited Methylene Blue molecules (MB) that yields a resonance energy red-shift and a broadening of LSPR profile.