Computer modeling and X-ray diffraction analysis of carbon nanotubes

The study of carbon materials in non-crysta11ine state and their identification in the experimental samples by diffraction methods of research is a complicated enough task because: 1) these materials have amorphous scattering patterns; 2) there are many polymorphs of carbon. The solution of this problem is a construction of theoretical models of different atom configurations, calculation, analysis, and comparison of the model’s diffraction patterns and matching them with the experimental radiographs. The aim of the work is to find whether we can use this approach to research carbon nanotubes (CNTs). So, a series of nanotube models of different configurations (by type, length, inner radius, chirality, the number of layers) were constructed in the work. For all simulated objects, we calculated theoretical diffraction patterns (using the Debye method). Then we made their analysis and comparison. As a result, we obtained identification information for the definition of some CNT’s structural characteristics (type, chirality, the number of layers, etc.) in the experimental samples. Moreover, the authors carried out X-ray research of the carbon material sample, which, hypothetically, contains CNTs. Then we constructed a corresponding model of the atomic structure, which scattering pattern is similar to the experimentally obtained radiograph. We noted in the article that in theoretical calculations of the models it is better to form various mixes of CNTs with different (in a small range) geometric characteristics and calculate the corresponding “average” scattering patterns. The obtained results give us evidences of the possibility to use X-ray analysis combined with the computer modelling in the study of carbon nanotubes.