Plasmon-mediated Polarization Anomalies in Surface Enhanced Raman   Scattering (SERS)
  We discuss the effect of the local field polarization in metallic nanostructures where large field enhancements can be induced by excitation of localized surface plasmons. To demonstrate the importance of these effects, we study a few model systems in 2D and 3D. As an experimental probe of this effect, we suggest to use depolarization ratios in Surface Enhanced Raman Spectroscopy (SERS) measurements. We attempt to relate the polarization of the local field to the depolarization ratios in SERS conditions. This approach could also lead to some better understanding of the SERS mechanisms at a microscopic level. 
E. C. Le Ru and P. G. Etchegoin