STM image of polyaniline with large sum counter-ions

Summary form only given. A very thin film of polyanfline ( PANI ) doped with p-toluenesulfonic acid was prepared by electrochemical polymerization on highly ordered pyrolylic graphite( HOPG ) substractes. The x-ray diffraction of this resulting film shows three strong diffraction at 2/spl theta/ = 9.97/spl deg/, 26.49/spl deg/ and 102.48/spl deg/, respectively, which are corresponding to periodic arrange of chain, interchain and counterions[ 1-2], respectively. A highly quality STM image of thid film was observed. The average diameter of bright dots are estimated to be 3.7/splAring/ which is consistent with the diameter of benzene rings. Therefore, we assign those bright dots as benzene rings. Moreover, the distance of the neighouring bright dots along the a diraction shown in STM image is calculated to be 8.6/spl Aring/. This is in good agreement with value of 9.07/splAring/ measured from x-ray diffraction. So, it is reasonable to assume the a diraction shown in STM image as the diraction of PANI chain. If hypotheses described above are considered and a tight interchaine contact shifted a quarter of the chain repeat unit are assumed, the distance between benzene rings along the diraction of the nearest neighuring interchain is calculated to be 6.0/splAring/. This is consistent with the measured value of 6.16/splAring/, which is the distance of the neighouring bright dots along the b diraction shown in STM image. Moreover, the angle between a and b diraction calculated based on our hypotheses is good agreement with measured value from STM image.