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 ∑| I 0 − I c |/∑ I net , is 0,125.