Rugged nanoparticle tracers for mass tracking in explosive events
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Rugged nanoparticle tracers for mass tracking in explosive events Lance Hubbard , Ryan Sumner, Martin Liezers, Trevor Cell, Clara Reed, Nicolas Uhnak, Caleb Allen, Brittney Berry, Hugh Currah, Erin Fuller, Erin Kinney, Nathaniel Smith, Michael Foxe, and April Carman, Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, WA 99354, USA Address all correspondence to Lance Hubbard at [email protected] (Received 17 July 2020; accepted 2 September 2020)
Abstract Tracing the flow of solid matter during an explosion requires a rugged tag that can be measured by a unique identifiable signature. Silicacovered semiconductor quantum dots (QDs) provide a unique and tunable photoluminescent signature that emits from within a sacrificial outer layer. Five types of silica-covered zinc sulfide QDs were synthesized and covalently bound to commercial luminescent powders. The combination of five dots and five powders enables a matrix of 25 unique tags. The tracers are shown to be tolerant of environments associated with chemical explosives and provides a unique tag to evaluate debris fields.
Introduction The development of identifiable tracers capable of tracking mass through a chemical explosion will allow data collection and model confirmation of debris dispersion by tagging the predetonation environment with unique luminescent particles. Recently, Anderson et al. used rare-earth-doped-yttria particles mixed with europium-doped zinc oxide nanoparticles to measure spatial tracking and temperature profiles of an explosive event.[1] Anderson et al. were able to track an event both spatially and thermally but were plagued by a large amount of optically inactive particles following the test explosion.[1] Previous efforts of material tracking date back to the 1950s on atolls in the Pacific Ocean during the nuclear testing era.[2] Tracer particles from a tower explosion were collected on several neighboring islands about 10 miles away. Only one island yielded enough material to measure the tracer particles.[2] Both experiments shed light on valuable information, such as fallout formation and debris origin, but sampling methods were rudimentary and the source material was identified qualitatively. Ruggedized quantum dots (QDs) protect the signature through the explosion, thereby improving the data accuracy and simplifying sampling. QDs provide a unique photoluminescent signature that can be tuned by the material’s composition and electronic confinement.[3,4] Ruggedizing the QDs with an optically transparent sacrificial layer enhances the nanoparticles’ survivability in an explosive event. For this research, zinc sulfide (ZnS) QDs were chosen as the phosphor material due to their intrinsic properties including high-temperature resistance, relatively stable crystalline lattice, photostability, and oxygen tolerance.[5] In this paper, we describe the synthesis of ruggedized QDs using a modified Stöber method. The QDs were encapsulated in
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a silica shell that was functionalized with a thiol-terminated ligand. In con
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