Study of carbon nano structured materials including activated carbon by using electron microscopy and simulation

本研究通过高分辨率透射电镜（HRTEM）、模拟和图像处理等手段，对活性炭等含0.7 nm以下超微孔的碳材料的纳米结构进行了分析。利用HRTEM观察不同离焦值下的非晶碳膜（Δfs），在考虑阻尼特性的情况下确定HRTEM物镜的相衬传递函数，并对传递函数进行模拟。利用二维快速傅里叶变换（2D-FFT）对非晶碳膜的HRTEM图像进行功率谱分析，并与仿真数据进行比较。通过对HRTEM图像的二维fft得到的功率谱中心点进行积分，可以知道碳材料的结构。该方法应用于聚苯乙烯基碳、沥青基碳和纳米碳纤维的分析。分析方法还应用于碳分子筛和其他活性炭，并与气体吸附进行比较。含有超微孔的碳分子筛不能吸附氮气和氩气，但可以在高压下吸附二氧化碳。通过HRTEM和图像分析方法得到的孔隙尺寸分布与气体吸附结果进行了比较。在高分辨率观测中，HRTEM成像依赖于HRTEM物镜的传递函数。传递函数对于非晶结构材料（如活性炭）的精确观察非常重要。HRTEM结合图像分析可用于超微孔结构分析，并有望成为确认气体吸附有效性的独立技术。通过本研究，改进了非晶态碳的分析方法。

In this study, the nano structure of carbon materials including activated carbons which contain ultra micro pores of under 0.7 nm in the size was analyzed by high resolution transmission electron microscopy(HRTEM), simulation and image processing.Amorphous carbon films are observed by HRTEM on different defocus values (Δfs) in order to determine the phase contrast transfer function of objective lens of the HRTEM with consideration with damping property as well as simulation of the transfer function. Power spectra of the HRTEM images of the amorphous carbon film obtained by 2 dimensional fast Fourier transform (2D-FFT) were compared to the simulation data. The structure of carbon materials can be known to be analyzed by integration their power spectra around the center point obtained by 2D-FFT of the HRTEM image. This method was applied to analyzing polypharaphenylene based carbons, pitch based carbons, and carbon nanofibers.The analysis method was also applied to a carbon molecular sieve and other activated carbons, and compared to gas adsorption. The carbon molecular sieve which contains ultramicropore could not adsorb N_2 or Ar but can CO_2 with high-pressure. Pore size distribution obtained by the HRTEM and image analysis method was compared to results of the gas adsorption. The HRTEM image depends on the transfer function of objective lens of the HRTEM in high-resolution observation. The transfer function is important for exact observation of amorphous structured materials such as activated carbons. The HRTEM combined with image analysis was shown to be useful for structural analysis of ultramicropore and was expected to be an independent technique for confirmation of gas adsorption usefulness. The analysis method of amorphous like carbons can be improved through this research.