Knowledge of the persistence of trace explosives materials is critical to aid the security community in designing detection methods and equipment. The physical and environmental factors affecting the lifetimes of particles include temperature, airflow, interparticle distance, adlayers, humidity, particle field size and vapor pressure. We are working towards a complete particle persistence model that captures the relative importance of these effects to allow the user, with known environmental conditions, to predict particle lifetimes for explosives or other chemicals. In this work, particles of explosives are sieved onto smooth glass substrates using particle sizes and loadings relevant to those deposited by fingerprint deposition. The coupon is introduced into a custom flow cell and monitored under controlled airflow, humidity and temperature. Photomicroscopy images of the sample taken at fixed time intervals are analyzed to monitor particle sublimation and characterized as a size-independent radial sublimation velocity for each particle in the ensemble. In this paper we build on previous work by comparing the relationship between sublimation of different materials and their vapor pressures. We also describe the influence of a sebum adlayer on particle sublimation, allowing us to better model ‘real world’ samples.
Michael R. Papantonakis, Viet K. Nguyen, Robert Furstenberg, Caitlyn White, Melissa Shuey, Christopher A. Kendziora, and R. Andrew McGill, "Physical and environmental factors affecting the persistence of explosives particles (Conference Presentation)," Proc. SPIE 10183, Chemical, Biological, Radiological, Nuclear, and Explosives (CBRNE) Sensing XVIII, 101830F (Presented at SPIE Defense + Security: April 11, 2017; Published: 7 June 2017); https://doi.org/10.1117/12.2262773.5458106221001.
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