An Experimental Investigation On The Polarization Effects Of The Stimulated Raman Scattering Of Liquid Molecules

The stimulated Raman scattering (SRS) will be produced in the Raman active molecular system when the system is irradiated by high power density pulse laser and the threshold of SRS is achieved. The Stokes and Anti-Stokes spectral lines with different frequency shifts and different orders will be formed from the different kinds of molecular system.Raman spectrum is a good supplementary of IR and electronic spectrum. Among Raman spectroscopy, SRS effect enriched wavelength range of stimulated emission and laser and developed research fields of interaction between intense laser and material. In the viewpoint of fundamental research, in spite of the promotion of Raman scattering technology, SRS provides a new way to understand energy level structure, symmetry property, motion situation, transition character, force constant, and molecular statistical law. And also SRS provides a new fundamental physical mechanism of generating intense coherent radiation. Since the foundation of Raman scattering, a lot of theoretical and experimental investigations have been carried systematically on the Raman spectra and the polarization properties of different kinds of molecular system. The research of the polarization effects of SRS is mainly focused on the optic fiber and few works on the liquid molecules were reported. So we present our experimental exploration on the polarization effects of SRS of some liquid organic molecules in this thesis.There are three chapters in this paper. The main contents are listed as following. In chapter one, the background, development and application of Raman scattering and SRS are introduced briefly. In chapter two, the basic principles of spontaneous, stimulated Raman scattering and experimental methods of SRS are presented. In the last chapter, the polarization effects of the stimulated Raman scattering of several organic molecules are investigated. The main contents are: (1) The stimulated Raman spectra of benzene, acetone, ethanol, methanol in different polarized directions are measured in the experiment under different polarized laser beam. (2) Relative intensity of the measured Stokes and Anti-Stokes stimulated Raman spectral lines are obtained by the fitting of the line profile. By analyzing intensity distribution of spectral lines in different polarized directions, some polarization characteristics of the spectral lines are discussed qualitatively.