Figure 4

Experimental and calculated IR spectra of imaginary part of the dielectric constant ε₂ and calculated IR active modes. (a) \({\varepsilon }_{2}\) spectra in the mid-IR range. In the calculated spectrum, the spectral width is set to be 32 cm⁻¹. (b) Expanded \({\varepsilon }_{2}\) spectra in the region of C=O stretching modes. In the calculated spectrum, the spectral width is set to be 13 and 23 cm⁻¹ for (i) and (ii) bands, respectively, so as to fit the experimental spectrum. (c) Calculated IR-active modes associated with O-H and C=O stretching vibrations.