Study of polyethylene structure by means of low-frequency Raman spectroscopy: Longitudinal acoustic mode and boson peak

The opportunities given by the low-frequency Raman spectroscopy for studying the ordered structures in polymers are presented and illustrated by examples of application of two techniques. The longitudinal acoustic modes (LAM) excited in straight chain segments of macromolecules are characteristic in linear semicrystalline polymers, while the Boson peak (BP) manifests itself in amorphous (glassy) polymers. Both these features are due to the laser light scattering from the acoustic vibrations localized either in the ordered one-dimension structures (LAM) or in the mid-range order correlation sphere (BP).