Resolving Nanodiamond Diffraction during Detonation of High Explosives*

Carbon condensation during high-explosive detonations occurs under extreme conditions and on very short time scales.  The nanoscale crystalline phases formed under these conditions provide key insight into the condensation pathways. While previous time-resolved measurements have confirmed a morphology, characteristic of detonation nanodiamond, observing the diffraction from nanodiamond, in-situ, remains a challenge. Using ultra-fast (sub-μs) X-ray diffraction with a narrow-band of polychromatic X-rays, we show that a broad peak corresponding to the diamond 111 can be observed at early-times, but is adjacent to a strong fluid-like peak that shifts to shallower angles as the detonation progresses. Challenges associated with the certainty and amount of diamond are discussed in light of results from a range of explosives that produce a broad range of carbon phases.