GROWTH AND CHARACTERIZATION OF SEXITHIOPHENE SINGLE-CRYSTALS

Single crystals of unsubstituted sexithiophene (6T) were produced by a sublimation technique. X-ray structure shows that the molecule has a quasi-planar all-trans configuration, the torsional angles between adj acent rings being lower than their respective standard deviation. The unit cell belongs to space group P2(1)/n and presents the herringbone packing common to a great deal of planar molecules. Owing to the well- defined orientation of the molecules in single crystals, the polarizat ion of vibration modes and coupling due to crystalfield effects could be unambiguously determined from polarized light IR spectroscopy. Rama n spectra of the single crystals are also presented and compared to th at of polycrystalline evaporated films.