Surface enhanced Raman scattering on silver grating: Optimized antennalike gain of the stokes signal of 104

Abstract

Using a silver grating of variable groove depth overcoated by a thin film of copper phthalocyanine, we measured an increase of the Raman efficiency of 10⁴ as compared to the flat case (copper phthalocyanine on a flat silver surface). This effect is due to the resonant excitation of delocalized surface plasmons. The value of 10⁴ corresponds to an optimum groove depth of the grating which acts as a high gain directive antenna when surface plasmons resonance is achieved at the Stokes frequency.