SERS effect in CO physisorbed on homogeneous and core-shell nanoparticle aggregates

Surface Enhanced Raman Scattering (SERS) is studied for a simple molecule (CO) physisorbed on a nanoparticle belonging to a nanoparticle aggregate, with well defined composition and architecture, in order to assess the effect of metal nanostructure on the Raman enhancement. The approach involves explicit consideration of the molecule, with due allowance for the characteristics of its radiated field, which are believed to be particularly important elements in determining enhancement from complex-shape aggregates. The electrodynamic problem for a nonresonant polarizable point dipole in the presence of an aggregate of spherical scatterers has been resolved numerically, extending to a multi-particle system the treatment put forward by Kerker.