Analysis of the High-Frequency Dielectric Properties of Weak Hydrogen
Bonded System
Summary
The main objective of this dissertation was to develop a new method of a simultaneous
optimization of both parts of complex dielectric permittivity spectra in the IR region. A
MATLAB code was developed for calculating, processing and plotting spectra of '(), ''(),
n() and k() for a given number of bands, the shape of which resulted from the assumed
damped harmonic oscillator (CDHO) model. In due process of optimization the gradientless
Powell algorithm was used. In the procedure of spectra processing the parameters
characterizing the damped harmonic oscillator: S, ,  and ∞ were optimized.
As the subject of this study the following systems of analogous compounds forming
and not-forming intermolecular hydrogen bond were selected:
• n-propanol, di-n-propylether;
• iso-propanol , di-iso-propylether;
• pyrrole, N-methylpyrrole;
• N-methylformamide and N,N-dimethylformamide.
The complex dielectric spectra of two amides listed above - the refractive index,
permittivity and dynamic polarizability - were obtained by the use of FT-IR transmission in
the NIR, MIR and VIS spectral ranges, including the use of quantitative thin-film techniques
in the MIR.
On the basis of the measured and properly processed spectra the molar vibrational
polarizability for selected spectral regions was determined. A new feature introduced in this
study was the analysis of the Pvib values for individual bands observed in the experimental
spectrum. This became possible by defining the parameters of the experimental bands in the
developed procedure and optimizing the experimental spectra. Comparison of the selected
bands contributions to the total Pvib between pairs of liquids allowed to quantitatively
characterize the weak hydrogen bond forming in the selected liquids.