THE STRUCTURE OF NEUTRAL POLYTHIOPHENE - AN APPLICATION OF THE RIETVELD METHOD

The crystal structure of polythiophene is analyzed by the Rietveld whole-fitting method on the X-ray diffraction powder profile. Experimental data allow only a bidimensional characterization of the structure in the plane orthogonal to the chain axis with a pgg symmetry (a = 7,79; b = 5,53 Å). Best fitting is obtained by assuming rigorous coplanarity of thiophene rings along the chain. The presence of few and weak layer-peaks is interpreted in terms of only partial ordering of chains along their axes. The final disagreement factor, in terms of ?|I0 - Ic|/? Inet, is 0,125.