FT-IR INVESTIGATIONS OF (BEDT-TTF)2I3 RADICAL SALTS

Fourier transform infrared absorption spectra of structurally differen t phases of the radical cation salt (BEDT-TTF)2I3 in the range of the molecular vibrations of the donor are presented. The low-temperature s pectra provide exact fingerprints of the different phases as long they have different unit cells. Additional differences concerning the posi tions of ethylene groups reflect themselves in the CH2-stretching vibr ations. As a result, it could be shown that the ethylene groups of the alpha(t)-phase and beta-phase must have a different order. Concerning the tempering of the different phases, it is shown that at least alph a(t)- and x(t)-(BEDT-TTF)2I3 are the same.