Morphological Variations of Explosive Residue Particles and Implications for Understanding Detonation Mechanisms

Abstract

The possibility of recovering undetonated explosive residues following detonation events is well-known; however, the morphology and chemical identity of these condensed phase postblast particles remains undetermined. An understanding of the postblast explosive particle morphology would provide vital information during forensic examinations, allowing rapid initial indication of the explosive material to be microscopically determined prior to any chemical analyses and thereby saving time and resources at the crucial stage of an investigation. In this study, condensed phase particles collected from around the detonations of aluminized ammonium nitrate and RDX-based explosive charges were collected in a novel manner utilizing SEM stubs. By incorporating the use of a focused ion beam during analysis, for the first time it is possible to determine that such particles have characteristic shapes, sizes, and internal structures depending on the explosive and the distance from the detonation at which the particles are recovered. Spheroidal particles (10-210 μm) with microsurface features recovered following inorganic charge detonations were dissimilar to the irregularly shaped particles (5-100 μm) recovered following organic charge firings. Confirmatory analysis to conclude that the particles were indeed explosive included HPLC-MS, Raman spectroscopy, and mega-electron volt-secondary ionization mass spectrometry. These results may impact not only forensic investigations but also the theoretical constructs that govern detonation theory by indicating the potential mechanisms by which these particles survive and how they vary between the different explosive types.

On the Formation and On the Surface of Inorganic Lead, Barium and Antimony Based Gunshot Residues: A Thermodynamic Approach

“…Recent works [72,73] have explored the formation of particles in two other different situations, i.e. welding fume particles originating from both the core and the covering of electrodes used in popular manners of welding steel and aluminium alloy constructions and post-blast explosive particles related to both inorganic and organic reactive materials.…”

Determination of residual low-order detonation particle characteristics from IMX-104 mortar rounds

“…Prior studies have characterized postdetonation particles using a variety of techniques. Steel witness plates surrounding a point of detonation at varying distances have been used to determine particle mass, and to some extent size, from high-order detonations of conventional explosives (Abdul-Karim, Blackman, Gill, and Karu 2016;Abdul-Karim, Blackman, Gill, Morgan, et al 2016;Borusiewicz et al 2013). Abdul-Karim, Blackman, Gill, and Karu (2016) found preliminary evidence for particle mass to relate to the inverse square of the distance from detonation, and they also found that mass decreases with increasing distance.…”

Explosion-related deaths: An overview on forensic evaluation and implications

“…Ballistic experts may also collect bullets, projectile fragments and evidence from explosive discharge residues from the body of the victim. Explosive traces should be analyzed by a forensic chemical expert in order to define the typology of explosive material [57]. Moreover, residual particles may be searched through the use of Scanning Electron Microscopy/Energy Dispersive X-Ray Spectroscopy (SEM/EDX), which allows different classes of particles to be defined according to their composition and images [5,58].…”