Role of localized surface plasmons in surface-enhanced Raman scattering of shape-controlled metallic particles in regular arrays

We studied the influence of localized surface plasmon resonance (LSPR) sustained by arrays of metallic nanoparticles on the efficiency of surface-enhanced Raman scattering (SERS). We found that the Raman enhancement that originates from the excitation of LSPR does depend on the particle shape. Two different shapes were investigated: cylindrical particles, for which the maximum of Raman enhancement occurred for a LSPR located around 650 nm, and ellipsoidal particles, which exhibit the strongest SERS signal at 700 nm. These results are compared to an analytical model in the quasistatic approximation. This model, though being quite simple, can give an explanation of the observed differences in terms of the lightning rod effect.