Summary of Nonlinear Raman Spectroscopy

In the previous subsections we briefly introduced some nonlinear techniques of Raman spectroscopy. Besides stimulated Raman spectroscopy, Raman gain spectroscopy, inverse Raman spectroscopy, and CARS, several other special techniques such as the Raman-induced Kerr effect [8.70] or coherent Raman 

All these nonlinear techniques represent coherent third-order processes analogous to saturation spectroscopy, polarization spectroscopy, or two-photon absorption (Chap. 7), because the magnitude of the nonlinear signal is proportional to the third power of the involved field amplitudes (8.18). 

The advantages of these nonlinear Raman techniques are the greatly increased signal-to-noise ratio and thus the enhanced sensitivity, the higher spectral and spatial resolution, and in the case of the hyper-Raman spectroscopy, the possibility of measuring higher-order contributions of molecules in the gaseous, liquid, or solid state to the susceptibility. 

Additionally, there are several good books and reviews on nonlinear Raman spectroscopy. For more thorough information the reader is therefore referred to [8.11,8.37,8.43,8.47,8.48,8.54,8.56,8.72]. 

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