Characteristic features of the low-frequency region of infrared spectra and a cluster model of the structure of liquids

The results of experimental and theoretical studies of the low-frequency region of infrared spectra and Raman scattering spectra in liquid cyclic hydrocarbons (arenes) and their halogen-substituted ones are analyzed. The results of experimental studies of 13 liquids in the range 20–700 cm$^{-1}$ using a high-resolution all-wavelength vacuum Fourier spectrometer (Bruker IFS 125 HR) are presented. It is shown that the appearance of spectral bands in the low-frequency region (the region of the “boson” peak) of the infrared spectra of liquids is due to the formation and decay of cluster formations in the structure of the liquid.