FT-IR investigations of (BEDT-TTF)2I3 radical salts

Abstract

Fourier transform infrared absorption spectra of structurally different phasis of the radical cation salt (BEDT-TTF)2I3 in the range of the molecular vibration of the donor are presented. The low-temperature spectra provide exact fingerprints of the different phases as long they have different unit cells. Additional differences concerning the position of ethylene group reflect themselves in the CH2-stretching vibrations. As a result, it could be shown that the ethylene groups of the αt-phase and β-phase must have a different order. Concerning the tempering of the different phases, it is shown that a least αt- and χt-(BEDT-TTF)2I3 are the same.