The infrared reflection spectra of the organic quasi-one-dimensional semiconductor triethylammonium (TCNQ)_{2} between 80 and 300 K are reported. Characteristic changes in the temperature dependencies of the bands assigned to the donor vibrations are observed. An interpretation of the electron-molecular vibration coupling in terms of the dimer theory is discussed. It is concluded that the thermal evolution of the spectrum corroborates the semiconductor-semiconductor type of phase transition attributed to the cation disorder.
An interpretation of the IR polarized spectra of the organic quasi-one--dimensional semiconductor triethylammonium (TCNQ)_{2}, between 80 and 300 K, is discussed in terms of the dimer and tetramer theories. It is concluded that the dimer model is acceptable only for describing high-T phase of TEA(TCNQ)_{2}. The tetramer model is more adequate for an interpretation of the IR spectra of the salt within the large temperature range. It is also shown that the phase transition influences distinctly neither vibronic (electron-molecular vibration coupled) modes nor conformity of the experimental spectra with calculated ones according to the dimer or tetramer theory.
Fourier transform IR absorption spectra of single crystals of the (ET)_{2}C_{60} complex grown from the CS_{2} solution as well as its components: C_{60} and ET, also grown from CS_{2} solution, are presented and discussed. It is shown that the rotation of C_{60} is strongly hindered and ET molecules are bent in the crystal structure of the complex. The arguments for the domination of the van der Waals interactions are given.
Spectral investigations of someμ-oxo-dimer complexes of trivalent metals (Mn, Fe) with two different ligands: tetraphenylporphyrin and tetranaphthylporphyrin (TNP), and fullerene (C_{60} and C_{70}) complexes withμ-oxobis[5,10,15,20-tetraarylporphyrinatometal (III)] (TXP-M)_2O dimer, where M = Fe, Mn and X = phenyl or naphthyl, are presented. Discussion of the main electronic and vibrational bands observed in the UV-Vis-IR and Raman spectra of both classes of fullerene-porphyrin systems is given. Experimental data are completed with the quantum chemical calculations of MnTNP^+ component.
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