| The work in this dissertation is mainly about techniques and applications of PARS (Photoacoustic Raman Spectroscopy) and RIKE (Raman Induced Kerr Effect), and also concerning on techniques of SRGS (Stimulated Raman Gain Spectroscopy) and CARS (Coherent Anti-Stokes Raman Scattering).1. Photoacoustic Raman Spectroscopy (PARS) techniqueThe PARS is a very sensitive spectral technique which can truly record the Raman spectrum of medium, and is favorable to observe the polarization effect of Raman spectrum. This technique was first reported by Barrett and Berry, and later adopted by some other authors. In our PARS experimental set-up, the employed two laser beams (one is called as main pump beam, and the other is called as Stokes beam ) counterpropagate into the sample cell, unlike the general arrangement where the two laser beams are combined by a 45°-setting diachronic mirror and propagate in the same direction. Such counterpropagating arrangement leaves out the diachronic mirror which is prerequisite in copropagation, and accordingly eliminates the limitation and inconvenience that are brought by the diachronic mirror, such as the small Raman shift and polarization measurement so on. Therefore, the application of counterpropagation to PARS is a contribution of us. Our experimental results show that counterpropagating set-up can also give the accurate and reliable data sensitively and easy to be operated.2. Raman Induced Kerr Effect (RIKE) techniqueRIKE is a technique based on Raman-resonant Four Wave Mixing(FWX). Compared to other FWX techniques, RIKE is easier carried out due to non-existence of phase-matching. On the other hand, because the signal can be achieved by eliminating the background of incident Stokes beam with a polarizer, RIKE is more sensitive than SRGS. For RIKE, the counterpropagating arrangement is also a good choice not only because it can absolutely remove the interference of CARS, but also because it can monitor only Stokes beam without consideration of filtering pump...
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