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Molecules. 2019 Sep 26;24(19). pii: E3494. doi: 10.3390/molecules24193494.

Surface Persistence of Trace Level Deposits of Highly Energetic Materials.

Author information

1
R3-C Research and Education Component of ALERT DHS Center of Excellence for Explosives Research, Department of Chemistry, University of Puerto Rico, Mayaguez Campus, Mayaguez, PR 00681, USA. leonardo.pacheco@unisimonbolivar.edu.co.
2
School of Basic and Biomedical Sciences, Universidad Simón Bolívar, Barranquilla, 080020 Atlantico, Colombia. leonardo.pacheco@unisimonbolivar.edu.co.
3
R3-C Research and Education Component of ALERT DHS Center of Excellence for Explosives Research, Department of Chemistry, University of Puerto Rico, Mayaguez Campus, Mayaguez, PR 00681, USA. jose.ruiz9@upr.edu.
4
Joseph Smith & Sons Inc., Capitol Heights, MD 20743, USA. jose.ruiz9@upr.edu.
5
Department of Chemistry and Biochemistry, George Mason University, Fairfax, VA 22030, USA. jose.ruiz9@upr.edu.
6
R3-C Research and Education Component of ALERT DHS Center of Excellence for Explosives Research, Department of Chemistry, University of Puerto Rico, Mayaguez Campus, Mayaguez, PR 00681, USA. michael.l.ramirez@gmail.com.
7
Department of Physics-Chemistry, University of Puerto Rico, Arecibo, PR 00614, USA. ricinfante@gmail.com.
8
R3-C Research and Education Component of ALERT DHS Center of Excellence for Explosives Research, Department of Chemistry, University of Puerto Rico, Mayaguez Campus, Mayaguez, PR 00681, USA. nataly.galan@unisimonbolivar.edu.co.
9
School of Basic and Biomedical Sciences, Universidad Simón Bolívar, Barranquilla, 080020 Atlantico, Colombia. nataly.galan@unisimonbolivar.edu.co.
10
R3-C Research and Education Component of ALERT DHS Center of Excellence for Explosives Research, Department of Chemistry, University of Puerto Rico, Mayaguez Campus, Mayaguez, PR 00681, USA. pacheco.londono@gmail.com.

Abstract

In the fields of Security and Defense, explosive traces must be analyzed at the sites of the terrorist events. The persistence on surfaces of these traces depends on the sublimation processes and the interactions with the surfaces. This study presents evidence that the sublimation process of these traces on stainless steel (SS) surfaces is very different than in bulk quantities. The enthalpies of sublimation of traces of four highly energetic materials: triacetone triperoxide (TATP), 2,4-dinitrotoluene (DNT), 2,4,6-trinitrotoluene (TNT), and 1,3,5- trinitrohexahydro-s-triazine (RDX) deposited on SS substrates were determined by optical fiber coupled-grazing angle probe Fourier Transform Infrared (FTIR) Spectroscopy. These were compared with enthalpies of sublimation determined by thermal gravimetric analysis for bulk amounts and differences between them were found. The sublimation enthalpy of RDX was very different for traces than for bulk quantities, attributed to two main factors. First, the beta-RDX phase was present at trace levels, unlike the case of bulk amounts which consisted only of the alpha-RDX phase. Second, an interaction between the RDX and SS was found. This interaction energy was determined using grazing angle FTIR microscopy. In the case of DNT and TNT, bulk and traces enthalpies were statistically similar, but it is evidenced that at the level of traces a metastable phase was observed. Finally, for TATP the enthalpies were statistically identical, but a non-linear behavior and a change of heat capacity values different from zero was found for both trace and bulk phases.

KEYWORDS:

FTIR; explosive; grazing angle; sublimation; thermogravimetric analysis

PMID:
31561514
PMCID:
PMC6804148
DOI:
10.3390/molecules24193494
[Indexed for MEDLINE]
Free PMC Article

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