Theoretical study of coated spherical metallic nanoparticles for single-molecule surface-enhanced spectroscopy

We investigate the possibility to use coated metallic nanoparticles for single-molecule surface-enhanced spectroscopy by extending the Mie theory. The aggregates of metallodielectric spheres of Au and Ag show a strong local intensity enhancement in the cavity between particles, which can result in up to a 10(14)-fold increase for surface-enhanced Raman scattering. We also examine the thickness of the coating layer, the size of the core, and the incident wavelength that determine the enhancement. (C) 2004 American Institute of Physics.