Temperature dependence of infrared spectra of (ET)4Hg3I8 crystals; H8- and D8-ET derivatives

Infrared spectra of H8-(ET)4Hg3I8 and analogous salt with deuterated ET molecule D8-(ET)4Hg3I8 are studied. Polarized reflectance spectra from single crystals and absorption spectra of powders are measured as a function of temperature. The influence of semiconductor-semiconductor phase transitions on IR spectra is considered. It is observed that the v27(b1u) mode of ET molecule couples with electrons.