Enhancement and extinction effects in surface-enhanced stimulated Raman spectroscopy

Surface-enhanced Raman spectroscopy (SERS) is a technique that allows one to probe the vibrational modes of molecules with great precision. However, current methods involve the enhancement of local fields from spontaneous Raman scattering near a metallic substrate. By utilizing stimulated Raman scattering over spontaneous Raman scattering, the effect of the enhancement of the local fields will be increased due to nonlinear excitations. An electromagnetic derivation for the enhancement of local fields near the surface of a small metallic sphere due to stimulated Raman scattering is performed. In addition, the non-trivial relationship between the enhancement and extinction of the Raman signal is considered. Using the effective medium approach, an expression for the scattered Raman field of a collection of metallic nanoparticles that includes both these effects is formulated. Optimal parameters for surface-enhanced stimulated Raman spectroscopy (SESRS) are proposed based on the study of enhancement and extinction phenomena in the collection of nanoparticles