ABSTRACT
In (inelastic) Raman scattering, the energy difference between exciting and scattered photons corresponds to vibrational transitions (modes) in the molecule. Since these modes are molecule-specific, Raman spectroscopy therefore constitutes a species-sensitive analytical measurement procedure. In the first part of this chapter, the fundamental framework for Raman scattering and spectroscopy is given, by and large phenomenologically—i.e., highlighting the most important measurement parameters and the intricacies associated with Raman scattering in gaseous, liquid, and solid samples. Complementing this descriptive picture are sets of key equations—often in tabular form to make comparison easier—which establish quantitative links between observed signals and molecular properties (e.g., the spectral Raman shift associated with vibrational modes, or polarization-dependent transition probabilities). The second part is dedicated to the experimental implementation of Raman spectroscopy, following the component chain from the laser excitation sources, via light delivery and collection systems (including relevant spectral filtering), through to signal detection and extraction of spectra. In the final part, a range of derivative techniques is briefly introduced, including among others the spontaneous modality of spatially offset Raman spectroscopy; enhancement techniques like surface- and tip-enhanced Raman spectroscopy; and nonlinear configurations like coherent anti-Stokes Raman scattering.
