Safer screening of explosive material reactivity by vibrational spectroscopy

18 Feb 2026 - Adam Michalchuk

With the aim to make the development of energetic materials such as explosives, propellants and pyrotechnics safer, a team of researchers from the University of Birmingham, the University of Edinburgh, and ISIS are pioneering a spectroscopic approach for the rapid, small-scale and non-destructive screening of explosive safety.

The INS spectrum for CL-20, collected on the Tosca spectrometer and the application of the vibrational up-pumping model to the INS spectrum, to extract a safety metric for CL-20

Obtaining a sensitivity metric for explosives from inelastic neutron scattering (INS) spectra. (Top) The INS spectrum for CL-20, collected on the Tosca spectrometer. (Bottom) Application of the vibrational up-pumping model to the INS spectrum (blue), to extract a safety metric for CL-20.

Energetic materials such as explosives and propellants are critically important for technologies ranging from mining and entertainment to defence. However, these materials release a large amount of energy when initiated, for example by mechanical impact, making them hazardous to handle. This hazard is especially prominent for new energetic materials whose behaviour is completely unknown.

Currently, to determine how easy it is to make an energetic material explode, scientists need to synthesise the material in gram-scale quantities. A drop hammer is then used to determine how much energy is needed to make it explode in a trial-and-error approach. Not only is this current approach costly and time consuming, but it poses significant risk to the people doing the testing.

In their latest paper, published in PCCP, the group have developed a safer screening approach using inelastic neutron scattering spectroscopy (INS) on the Tosca instrument at ISIS. Unlike laboratory spectroscopies, INS provides a complete fingerprint of the vibrational spectrum of a material, free from quantum mechanical selection rules. More importantly, INS spectroscopy provides access to the low-frequency lattice vibrations, which govern how mechanical energy from a mechanical impact is absorbed by the material and ultimately triggers the explosive reaction.

By feeding these INS spectra into a computational model of vibrational up-pumping, which was also developed using input from the Tosca instrument, the research team can determine how much energy is absorbed by the explosive after a mechanical impact. This provides a key predictive metric for the reactivity (and hence safety) of energetic materials.

The spectroscopic screening methodology that is being developed and validated with INS spectroscopy is now paving the way to a second approach that makes use of a portable low-frequency THz-Raman spectrometer. Once fully developed, with the help of further INS spectroscopy, this THz-Raman approach promises a rapid, small-scale and non-destructive technique to screen samples as small as milligram size for energetic material safety.

This work highlights how neutron spectroscopy can do more than reveal fundamental material properties: it can make the development of new energetic materials safer and faster. By screening sensitivity early, researchers can design explosives that meet performance needs while minimizing risk, paving the way for safer technologies in critical sectors.

The full paper can be found at: A. A. L. Michalchuk, C. A. Morrison, C. R. Pulham and S. Rudić, Phys. Chem. Chem. Phys., 2025, 27, 25276–25281. DOI; 10.1039/D5CP03040D

Further information about the vibrational up-pumping model: A. A. L. Michalchuk, Chem. Commun., 2024, 60, 14750–14761; A. A. L. Michalchuk, S. Rudić, C. R. Pulham and C. A. Morrison, Chem. Commun., 2021, 57, 11213–11216.