Chapter 2 - Raman spectroscopy and related optical techniques

Abstract

This chapter presents a self-contained introduction to Raman spectroscopy and related optical techniques, which is more general than what is actually needed for surface-enhanced Raman spectroscopy (SERS) in several aspects, but covers the essential concepts and provides a unifying view of the basic material. There are tens of possible approaches to the field of Raman spectroscopy reported in the literature over the years. All of them are equivalent at some level and all of them have advantages and disadvantages. It highlights the aspects that are more important for both molecular Raman spectroscopy and SERS. The level of presentation is always a compromise between clarity and depth. While avoiding sophisticated calculations throughout, it tries nevertheless not to sacrifice depth, and presents the main formulas and their physical relevance where required. It also provides a gradual approach to the subject with an underlying thread toward the ultimate goal of the book: explaining SERS and related effects. The presentation of the material in this chapter is therefore in many aspects recursive; in the sense that many times it comes back to the same concepts but from a slightly different point of view. It introduces the Raman effect and other basic optical processes such as absorption and fluorescence from a relatively simple phenomenological point of view. Although this description is sufficient to move on to the description of SERS and related plasmonic effects, it provides additional information on the same topics as well, but on an increased level of complexity.