Structure Analysis by Vibrational Spectroscopy

Abstract

Infrared and Raman spectroscopies are often used for the identification of chemical functional groups. These spectroscopic methods are quite powerful for the study of chain conformation, chain packing mode in the crystal lattice, and interatomic interactions. The methods how to know the IR/Raman activities, how to predict the number and polarization of the bands (factor group analysis), and how to calculate the vibrational frequencies and intensities of the bands (normal modes calculation) are learned in a concrete way. The IR and Raman spectra characteristic of polymer substances are also studied, which include the progression bands, the longitudinal acoustic modes, the critical sequences, etc., in relation to the structural transitions of polymers in the crystallization process, for example. The vibrational spectra are sensitive to the structural disorder included in the chain conformation as well as in the chain packing state, which will be known from the calculation of density of states function. The principles of the spectral measurements, the inner structure of spectrometers, and the various kinds of spectral measurement methods are learned. The preparation methods of the samples necessary for the IR and Raman spectral experiments are also studied in detail.KeywordsInfrared spectraRaman spectraFactor group analysisNormal modes treatmentSpectroscopic measurements