Crystal Structure and Group Theory:
Using Symmetry Groups to Determine
Raman Active Modes of Vibration
Sarah Post '04

Abstract:

    An interesting tool that can be used to analyze the structure of crystals is that of Raman spectroscopy, in which a laser is directed at a sample and the energy is changed by the interaction with the vibrational phonons. This change in energy is displayed as a shift in the wavelength; often, with a visible light laser, the light that is shifted is still in the visible range. The vibrational modes of the crystal can be determined by studying the structure of the crystal; this is simplified using group theoretical methods and particularly the method of factor group analysis. In this paper, I will first discuss the phenomenon of Raman scattering and then derive the procedures of group theory used to analyze the crystal structure. I will then go through the analysis using several crystals including Sapphire, Diamond, and TiO₂ whose spectrum will then be observed from the spectrometer.

   For more information, contact Dr. Catherine Jahncke:

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