The determination of energies of the hydrogen bonds and small radius polarons by IR spectra of ferroelectric liquid crystals

Abstract

For all studied substances the absorption bands in the region of 1 eV have been observed. At the phase transition to ferroelectric and nematic phases the position of the maximum was shifted and the value of the absorption in the band maximum was changed as the temperature dependence of the conductivity. That allows one to attribute this absorption band at 1 eV to the small radius polaron. The activation energy obtained with optical method (0.2-0.4 eV) is in conformity with one from the resistance temperature dependence. From IR spectra of the studied substances, the weak hydrogen bonds C=O … H—C one found to have energies of about 0.1 eV/molecule in the solid crystal phase. At the phase transition to ferroelectric and nematic phases, the energy of the hydrogen bonds decreases.