Chapter 4 - SERS enhancement factors and related topics

Abstract

This chapter discusses the fundamentals of the surface-enhanced Raman scattering (SERS) effect. SERS consists in using the large local field enhancements that can exist at metallic surfaces (under the right conditions, typically by profiting from localized surface plasmon resonances) to boost the Raman scattering signal of molecules at (or close to) the surface. A similar approach can be used to boost the fluorescence signal, and it is called surface-enhanced fluorescence. That technique is also discussed in this chapter in the context of SERS. It addresses the issues such as how much the signal can be boosted, i.e. to know what the enhancement factor is, and what its physical origins are, by defining rigorously the SERS enhancement factors, and then by discussing their origin, with a strong emphasis on the electromagnetic (EM) mechanisms. It only focuses on the methodology and the physics of the phenomena, not on the actual solution of the EM problem for a particular geometry. It therefore always assumes that it has a solution of the EM problems it may encounter. Furthermore, the theoretical results of this chapter are illustrated with concrete examples.