short communications
Anomalous X-ray diffraction was performed at the sulfur K edge of the partially crystalline conducting polymer poly(3-octylthiophene) (P3OT). This is the first time anomalous diffraction at the sulfur edge has been used to obtain additional information on the structure of a polymer. A strong wavelength intensity variation of the 100 reflection was observed. This intensity change and the variation of the fluorescent scattered background corroborate excellently with the theory and theoretical intensity calculations confirm previously suggested structural models.