碘掺杂聚乙炔的正电子湮没谱和结构缺陷转变

Positron Annihilation Lifetime Spectra and Structural Defect Transformation in Iodine-Doped Polyacetylene

本文研究了反式碘掺杂聚乙炔[CH(I_3)_y]_x在室温下正电子湮没寿命随掺杂浓度y的变化关系,发现y约在0.0025和0.043处寿命谱出现明显的突变.计算了杂质势和链间耦合积分.用链间耦合随掺杂浓度增强的概念,说明了出现上述两个突变的原因和主要元激发的转变,解释了磁化率随掺杂浓度变化的实验规律,讨论了三个区域的导电模型和电导率随温度的变化关系.

The positron annihilation lifetime as a function of the doping concentration iodine-doped trans-polyacetylene [CH(I3y)]x at room temperature is studied. Evident abrupt changes are found in positron lifetime spectra with doping concentration y at about 0.0025 and 0.043 respectively. The impurity potential and interchain coupling integral have been calculated. The concept of closer interchain coupling with an increase of y is used to illustrate the cause of abrupt changes and the transformation of main elementary excitations, and to explain the experimental law concerning the variation of susceptibility with doping concentration. Owing to different elementary excitations in three doping concentration regions, the conducting mechanisms are also different. The conduction model and the conductivity as a function of temperature in the three regions are discussed respectively.