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142 Raman Spectroscopy and Applications

Additional information is available at the end of the chapter Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/65482

#### **Abstract**

Vibrational Raman spectroscopy, one of the experimental techniques available, is applied for characterization and analysis of molecular samples in different areas such as medical, food and environmental analysis. Application of the Raman technique is mostly similar to the application of infrared and near-infrared absorption spectroscopy, i.e. only the spectral distribution is analysed. The goal of the present chapter is to demonstrate that the amount of molecular information (also for solutions and powders) can be increased considerably by analysing also the polarization of the Raman and resonance Ramanscattered light. The goal is achieved through: (1) a discussion of the basic properties of Raman scattering with special focus on polarization and polarization dispersion. The discussion includes the rotational invariants of Raman tensors, the non-commuting generator approach to molecular symmetry as a tool for construction of state and Raman tensors for single molecules and dimers and higher aggregates and thereby predict the polarization; (2) a discussion of two illustrative case studies: Case study 1: Aggregation of haemoglobin in red blood cells (RBC); and Case study 2: *In vitro* polarization resolved RRS study of dye-sensitized solar cells.

**Keywords:** polarization, state tensor, Raman tensor, aggregation, non-commuting generators
