S045-0007
High Temperature and Pressure Regime Soot Microphysical and Chemical Analysis for Real-Time Atmospheric Detection of High Explosives
Monday, 14 December 2020
Poster
Allison C Aiken1, Rachel Huber2, Andrew Schmalzer2, Mark Boggs2, James Edward Lee3, Kyle Gorkowski2 and Manvendra Krishna Dubey1, (1)Los Alamos National Laboratory, Los Alamos, NM, United States, (2)Los Alamos National Laboratory, Los Alamos, United States, (3)Los Alamos National Laboratory, EES-14: Earth Systems Observations, Los Alamos, NM, United States
Abstract:
Submicron carbonaceous aerosols generated by traditional combustion sources as well as explosions contain soot. Particulate soot contains chemical and microphysical signatures associated with the fuel, energy source and the environment under which it was formed. To study climate radiative forcing impacts, soot size, mass and number concentrations are measured in real-time from aircraft and ground sites. Their long-range transport in the troposphere and stratosphere from large fuel and energetic sources, such as wildfires and oil fires, has been observed over distances of thousands of kilometers and timelines of weeks to months. Here, we harness recent advancements in aerosol chemistry and real-time measurements that are ultra-sensitive and chemically-selective to identify detonation soot. Detonation soot physical, optical and chemical properties are contrasted with biomass burning and fossil fuel emission sources that have been more extensively studied over the last decade. Detonation soot properties are contrasted with traditional combustion soot sources using our online field-deployable instrumentation.
We identify detonation soot from two well-known high explosive composites (1) Comp-B: trinitrotoluene (TNT) and 1,3,5-Trinitro-1,3,5-triazinane (RDX) and (2) PBX 9501: 1,3,5,7-Tetranitro-1,3,5,7-tetrazoctane (HMX) under controlled atmospheres (Air and Argon). With the Soot Particle Aerosol Mass Spectrometer (SP-AMS) we can detect fullerenes and polycyclic aromatic hydrocarbons on the soot at very low detection limits (~ng/m3). The detonation soot had small mobility diameters (< 100 nm) and unique optical and chemical signatures that depended on the explosive composite composition, detonation atmosphere and pressure. Single Scattering Albedos (SSA: the ratio of light scattering-to-extinction) from 0.3 (dark) to 0.8 (light) and Absorption Angstrom Exponents (AAE) from 0.5 (traditional soot) to 2.0 (highly absorbing in the near-UV) were measured across 405 to 870 nm wavelengths and are related to the explosive composite composition and detonation conditions. Offline analysis of inorganics and metals is also used to validate aerosol trace-metal detection and to assess the scavenging of soot by rain and clouds during atmospheric transport.
