How Shape of Simulated Graphene Sheets Affects Debye Scattering Patterns

This research is about understanding the structure of a subset of graphitic stardust found in primitive meteorites (e.g. the Murchison meteorite). The carbon grains of interest exhibit a core-rim structure, where the core – with a density less than that of the graphitic rim – comprises the majority of the grain. Previous studies have shown that the cores are comprised primarily of unlayered graphene, and it has been hypothesized that the cores are the result of the rapid freezing (quenching) of a liquid carbon droplet. Electron diffraction is sensitive to small differences in crystal structure and simulated electron diffraction powder patterns can be used to explore the average shape of the graphene within the cores. Here, we seek to improve upon previous attempts to fit the core diffraction data by applying the Debye scattering formula to simulated graphene crystals with an anisotropic, triangular shape. The apex angle of the sheets is varied in each simulation, as we seek to explain differences between the simulated graphene fit and the stardust, and resolve the average structure of graphene within the cores