Surface enhanced Raman scattering from metallic nanoshells with nonlocal dielectric response

The Gersten–Nitzan model is applied to study the surface enhanced Raman scattering from a molecule adsorbed on a spherical metallic nanoshell. The nonlocal dielectric response from the nanoshell has been accounted for by using a phenomenological model. For a fixed outer radius of the shell, the enhancement ratio is calculated over a large range of scattering frequency and inner radius of the shell, including the case of a solid metallic particle. The effect due to different core materials is also studied. It is concluded that the nonlocal effects can be significant for very close molecule–shell distances, and for shells with very small sizes and/or thickness, leading to smaller enhancement in general. This can affect the plasmon resonances as well as the optimal shell thickness for the shell acting as a Raman enhancer.