Optimization of Raman Signal Enhancement in Kretschmann Configuration

Several experimental and theoretical studies [1,2,3] of Surface Plasmons Enhanced Raman Scattering (SPERS) in Kretschmann geometry (prism-metal-dielectric stacks) have demonstrated that it is possible to use surface plasmons (SP) to enhance Raman scattering from molecules adsorbed on a metal film. The enhancement process originates from two contributions: First, excitation of SP at pump frequency (ωi) and second, excitation of SP at Stokes frequency (ωs). To get the strongest Raman signal, scattered light must be detected on the prism side [3]. Indeed, the collected light comes from the outcoupling of SP at the Stokes frequency. In an experiment of SPERS, the Raman intensity depends on the distance of the active molecules to the metal surface [2]. Moreover, it has been suggested [3] that the thickness of the metal film deposited onto the prism should also be taken into account if one wants to improve the limit of detection.