Vibrational spectroscopy of glasses

Vibrational spectroscopy is one of the most powerful techniques for studying the structure of non-crystalline materials. It is particularly useful for probing vibrational motions of non-bridging atoms or ions or those of weakly coupled bridging species. Among the different vibrational methods available, infrared absorption and Raman scattering will be considered in detail, along with the specific types of structural information which can be extracted in each case, either directly or through comparison between spectral data and model calculations. Several types of inorganic glasses are examined, including oxide, chalcogenide and halide systems, for which tentative selection rules are presented. The problem of extracting the vibrational density of states from spectroscopic data is also addressed, together with the effects of different Raman data reduction procedures on the so-called “Boson” peak exhibited by most inorganic glasses.