Experimentally Interrogating Detonation Chemistry on Sub-Nanosecond to 100-Nanosecond Timescales

Trevor Willey | 21-ERD-023

Project Overview

Direct experimental measurement of chemical reactions during high explosive detonation remains challenging. Theory and modeling have long preceded experiment in the fundamental physical and chemical kinetic properties of detonation, and experimentation at the relevant timescales are needed to both validate models and provide fundamental understanding of detonation. In this LDRD project, two approaches, x-ray diffraction and core-level x-ray Raman, were developed and used to further experimental capabilities to address this gap.

We further developed dynamic x-ray diffraction to directly detect nanodiamond formation during detonation, providing experimental data towards resolving longstanding controversy in the scientific literature, and although the full kinetics have not yet been fully mapped, diamond diffraction appears on the same timescales as detonation soot formation. In the second research thrust, we have developed core-level x-ray Raman for use with high explosives. This technique provides information analogous to x-ray absorption spectroscopy and electron energy loss spectroscopy, but uses inelastic scattering of hard x-rays that can interrogate chemistry around light elements much deeper into the material. The low cross section and requisite high solid angle collection have both hindered its use for ultra-fast spectroscopy. We developed and tested a high-q spectrometer which will substantially increase cross section and signal-to-noise, showing this method will also not dramatically alter, compared to x-ray absorption, the most discriminating spectral features of C, N, and O from various high explosives and expected detonation products. We have also used x-ray Raman combined with OCEAN electronic structure calculations to explore dynamic photodegradation mechanisms in PETN and CL-20 explosives. This provides a pathway towards implementing capability to dynamically explore chemistry at an x-ray free electron laser.

Mission Impact

The project directly addresses institutionally stated mission research challenges in high explosive physics, chemistry, and materials science. LLNL has an ongoing need to develop new diagnostics that can measure the temperature and product set of chemical reactions in-situ at nanosecond resolution and micron length scale. This LDRD has furthered abilities to perform x-ray diffraction on detonating explosives, and for the first time used core-level x-ray Raman to measure high-explosive chemistry within the bulk of the materials. These novel diagnostic developments at next-generation light sources enable new methods of both discovery class science, and detonation model validation by improving our ability to measure detonation properties and provide feasibility for one pathway to directly measure chemistry. Core-level X-ray Raman can measure local, element specific chemical changes, potentially with single pulses at XFEL sources. These developments are important steps towards potential future large-scale NNSA investments in light sources, such as the Materials Under Extreme Conditions Upgrade (MEC-U) and the Defense Materials Science Sector (DMSS.)

Publications, Presentations, and Patents

Trevor M Willey, Jonathan RI Lee, Daniel Brehmer, Oscar A Paredes Mellone, Lasse Landt, Peter R Schreiner, Andrey A Fokin, Boryslav A Tkachenko, Armin de Meijere, Sergei Kozhushkov, Anthony W van Buuren, "X-ray spectroscopic identification of strain and structure-based resonances in a series of saturated carbon-cage molecules: Adamantane, twistane, octahedrane, and cubane." Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, 39 (5) 053208 (2021) https://doi.org/10.1116/6.0001150

Oscar A Paredes-Mellone, Michael H Nielsen, John Vinson, Konmeng Moua, K Dean Skoien, Dimosthenis Sokaras, Trevor M Willey, "Investigating the electronic structure of high explosives with X-ray Raman spectroscopy," Scientific Reports, 12, 1, 19460 (2022) https://doi.org/10.1038/s41598-022-24066-z

Paredes-Mellone, O.A., Nielsen, M.H., Vinson, J. et al. Investigating the electronic structure of high explosives with X-ray Raman spectroscopy. Sci Rep 12, 19460 (2022). https://doi.org/10.1038/s41598-022-24066-z

Trevor Willey, "Investigating high-explosive electronic structure and radiation induced decomposition by X-ray Raman scattering" (Poster Presentation, SSRL/LCLS Users' Meeting, Virtual, September, 2021). 

Oscar Paredes-Mellone, Dimosthenis Sokaras, Trevor Willey, Mike Nielsen, Arianna Gleason, G. V. Taylor, J. A. Hammons, "Resolving Nanodiamond Diffraction during Detonation of High Explosives" (Presentation, American Physical Society March Meeting, Chicago, IL, March, 2022).

O. A. Paredes-Mellone, D. Sokaras, T. M. Willey, M. H. Nielsen, A. E. Gleason, "Unimolecular Decomposition of High Explosives Observed by X-ray Raman Scattering" (Presentation, Inelastic X-ray Scattering Conference, Oxford, United Kingdom, August 2022).

Oscar Paredes-Mellone, Michael Nielsen, Konmeng Moua, Kyle Dean Skoien, John Vinson, Dimosthenis Sokaras, Trevor Willey, "Investigating high-explosive electronic structure and radiation induced decomposition by X-ray Raman scattering" (Presentation, 23rd Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter -SCCM23, Chicago, IL, June 18-23, 2023).

Trevor Willey, Joshua Hammons, Michael Nielsen, Amani Ebrahim, Gregory Taylor, Oscar Paredes Mellone, Lisa Lauderbach, Ralph Hodgin, Nicholas Sinclair, Adam Shuman, Yuelin Li, Pinaki Das, Ray Gunawidjaja, Erik Hansen, Konmeng Moua, Steven Pease, Sorin Bastea, Dimosthenis Sokaras, Larry Fried, "Monitoring Formation of Detonation Nanodiamond and Other Novel Carbon Nanostructures Using Advanced X-ray Scattering and Spectroscopy Techniques" (Presentation, 23rd Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter - SCCM23, Chicago, IL, June 18-June 23, 2023).