Advanced X-Ray Scattering and Spectroscopy Techniques to Monitor Formation of Nanodiamond and Other Novel Carbon Nanostructures During Explosive Detonations

Carbon nanomaterials synthesized through detonation, including nanodiamonds, are known to form aggregates requiring postprocessing to separate. We are using advanced, synchrotron-based time-resolved x-ray scattering to observe these nanomaterials form during the actual detonation events. The nascent morphologies depend on explosive used and what phase carbon products reach under differing pressure and temperature conditions. In all cases producing nanodiamond, aggregation into low fractal dimension structures is apparent as early as 100 ns, suggesting that aggregation occurs on timescales comparable to particle formation. A counterexample is the case of a high-explosive that reaches pressures and temperatures deeply into the carbon liquid phase and that ultimately produces novel carbon nano-onion structures. In this case, no hierarchical scattering was observed for at least 10 μs behind the detonation front. The novel and varied nanomaterials produced by carbon-rich explosives, and what parameters may be tuned during detonation to affect detonation nanodiamond synthesis will be discussed. Additionally, we are now beginning to determine the feasibility of time-resolved core-level x-ray Raman, or variants thereof, implemented at next-generation x-ray light sources, to interrogate nitrogen, carbon, and/or oxygen chemical evolution at nanosecond to microsecond timescales during detonation.