纳米碳管的电子衍射及其螺旋度测量

本文对电弧放电和催化剂热解碳氢气法制备的多层直形纳米碳管的倒空间及其螺旋度，采用电子衍射进行了研究。结果表明：尽管制备方法不同，两类多层管的结构相似，皆由螺旋和非螺旋的单层石墨管组成；对其倒空间的分析以及系列倾转电子衍射实验证明，衍射图中测得的表观螺旋度值随和射条件而改变，只有在垂直入射条件下该值才代表碳管的真实螺旋度；

Electron Diffraction Study of Carbon Nanotubes and The Measurements of Their Helicities

Straight carbon nanotubes with multishells produced by arc discharge and pyrolysis of organic gases using metal particles as catalysts have been investigated by means of electron diffraction. The results show that two kinds of carbon nanotube have similar internal structure no matter how many differences exist during their growth process, i.e. both of them composed of concentric cylinders, each formed by seamless graphene tubes with diameters of nanometer order of magnitude. A tilting series of diffraction patterns of a multishell nanotube and an analysis of the reciprocal model for the tubes have demonstrated that the value of apparent helicities of nanotubes measured from a diffraction pattern are dependent on the direction of the incident beam and only the measurements under normal condition can represent the true helicities. A simple method has been introduced to deduce the true helix angle from an inclined diffraction pattern.