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Sun ZJ, Li H, Zhu W. Reactive molecular dynamics simulations on the decomposition process of 1,3,5-trinitro-1,3,5-triazine crystal under high temperatures and pressure. J Mol Model 2023; 29:292. [PMID: 37615822 DOI: 10.1007/s00894-023-05656-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Accepted: 07/07/2023] [Indexed: 08/25/2023]
Abstract
CONTEXT Reactive molecular dynamics simulations were performed to study the decomposition processes of 1,3,5-trinitro-1,3,5-triazine (RDX) crystal under high temperatures (2100, 2400, 2700, and 3000 K) and detonation pressure (34.5 GPa) and 0 GPa. It is found that the initial decomposition paths of RDX under different temperatures coupled with detonation pressure are similar, which is due to the N-NO2 bond breakage to release NO2. The formation rates of N2 and H2O are significantly affected by temperature, while those of CO2 are less influenced. The C atoms finally formed C clusters. As the temperature rises, the decomposition speeds up, indicating that the high temperature accelerates the decomposition. Applying pressure can reduce the reaction energy barrier and accelerate the decomposition. METHODS The RDX model was constructed using the Materials Studio 7.0 package. All MD simulations were performed based on the ReaxFF force field in the LAMMPS software package, and the crystals were visualized using the OVITO software package. The time step was 0.1 fs, and the total MD simulation time was 200 ps. DFT calculations were carried out at the B3LYP/6-311G(d,p) level using the Gaussian 09 package.
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Affiliation(s)
- Zi-Jian Sun
- Institute for Computation in Molecular and Materials Science, School of Chemistry and Chemical Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China
| | - Hui Li
- Institute for Computation in Molecular and Materials Science, School of Chemistry and Chemical Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China
| | - Weihua Zhu
- Institute for Computation in Molecular and Materials Science, School of Chemistry and Chemical Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China.
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Zhang XX, Xue ZH, Wang Z, Yan QL. Thermal Reactivity of High-Density Hybrid Hexahydro-1,3,5-trinitro-1,3,5-triazine Crystals Prepared by a Microfluidic Crystallization Method. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:7503-7513. [PMID: 37186958 DOI: 10.1021/acs.langmuir.3c01003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
In this paper, the two-dimensional (2D) high nitrogen triaminoguanidine-glyoxal polymer (TAGP) has been used to dope hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) crystals using a microfluidic crystallization method. A series of constraint TAGP-doped RDX crystals using a microfluidic mixer (so-called controlled qy-RDX) with higher bulk density and better thermal stability have been obtained as a result of the granulometric gradation. The crystal structure and thermal reactivity properties of qy-RDX are largely affected by the mixing speed of the solvent and antisolvent. In particular, the bulk density of qy-RDX could be slightly changed in the range from 1.78 to 1.85 g cm-3 as a result of varied mixing states. The obtained qy-RDX crystals have better thermal stability than pristine RDX, showing a higher exothermic peak temperature and an endothermic peak temperature with a higher heat release. Ea for thermal decomposition of controlled qy-RDX is 105.3 kJ mol-1, which is 20 kJ mol-1 lower than that of pure RDX. The controlled qy-RDX samples with lower Ea followed the random 2D nucleation and nucleus growth (A2) model, whereas controlled qy-RDX with higher Ea (122.8 and 122.7 kJ mol-1) following some complex model between A2 and the random chain scission (L2) model.
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Affiliation(s)
- Xue-Xue Zhang
- Science and Technology on Combustion, Internal Flow and Thermo-Structure Laboratory, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, People's Republic of China
| | - Zhi-Hua Xue
- Science and Technology on Combustion, Internal Flow and Thermo-Structure Laboratory, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, People's Republic of China
| | - Zikangping Wang
- Science and Technology on Combustion, Internal Flow and Thermo-Structure Laboratory, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, People's Republic of China
| | - Qi-Long Yan
- Science and Technology on Combustion, Internal Flow and Thermo-Structure Laboratory, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, People's Republic of China
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Xu WS, Zhu J, Hu YF, Ji GF. Molecular Dynamics Study on the Reaction of RDX Molecule with Si Substrate. ACS OMEGA 2023; 8:4270-4277. [PMID: 36743027 PMCID: PMC9893248 DOI: 10.1021/acsomega.2c07512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Accepted: 01/11/2023] [Indexed: 06/18/2023]
Abstract
RDX is widely used in various explosion situations, and there are many studies on its detonation performance, safety, preparation, etc. Research on preparation of β-RDX is mainly conducted by experiments. In recent years, part of the research points to the use of substrate as a medium to produce β-RDX faster. Based on this guidance, our work aims to theoretically solve the physical and chemical processes that RDX may experience in the production process through numerical simulation. In this work, molecular dynamics simulation is set up for the interaction between RDX and a Si clean surface and a Si hydroxyl saturated surface separately, and a higher precision simulation is set up to verify the reliability of the results. NCI analysis is also used to guess the possible phase transition mechanism in the simulation results. In the simulation process, a 7 × 7 Si clean surface, a 3 × 3 Si clean surface, and a 7 × 7 Si-OH surface are set, and each surface adsorbs one α-RDX. The semiempirical Gfn1-xtb method is used for the 7 × 7 surface, and the DFT method is used for the 3 × 3 surface. The calculation results confirmed by high-precision results show that RDX molecules will react with the dangling bonds on the Si surface. Three conformations of RDX were found on the hydroxyl saturated surface of Si. The isosurface generated by the NCI method is used to analyze the reasons for the formation of these conformations.
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Affiliation(s)
- Wei-Sen Xu
- Department
of Engineering Mechanics, University of
Science and Technology of China, Hefei 230026, Anhui, P. R. China
- Institute
of Fluid Physics, China Academy of Engineering
Physics, Mianyang 621900, P. R. China
| | - Jing Zhu
- Institute
of Fluid Physics, China Academy of Engineering
Physics, Mianyang 621900, P. R. China
| | - Yan-Fei Hu
- Department
of Applied Physics, Chengdu University of
Technology, Chengdu 610059, P. R. China
| | - Guang-Fu Ji
- Institute
of Fluid Physics, China Academy of Engineering
Physics, Mianyang 621900, P. R. China
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Batyrev IG, Byrd EFC, Sausa RC. Single-Crystal Diffraction, Raman Spectroscopy, and Density Functional Theory of DTO [ N-(1,7-Dinitro-1,2,6,7-tetrahydro-[1,3,5]triazino[1,2- c][1,3,5]oxadiazin-8(4H)-ylidene)nitramide]. J Phys Chem A 2022; 126:6648-6656. [PMID: 36126112 DOI: 10.1021/acs.jpca.2c04937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A combined experimental and modeling study of energetic compound N-(1,7-dinitro-1,2,6,7-tetrahydro-[1,3,5]triazino[1,2-c][1,3,5]oxadiazin-8(4H)-ylidene)nitramide [C5H6N8O7, (DTO)] has been performed. We report its crystal structure, solid-phase heat of formation, and its vibrational and electronic structure obtained by single-crystal X-ray diffractometry, Raman spectroscopy, and density functional theory (DFT). DTO exhibits two adjoining six-membered rings, a triazine ring (C3N3) and an oxadiazine ring (C3N2O) ring containing two nitro functional groups and one nitroamino group. DTO crystallizes with four molecules in its unit cell and presents a density of 1.862 kg/m3 at 298 K, in excellent agreement with both DFT calculations performed both at the molecular level using the B3LYP with the 6-311+G** basis set and the solid-state level using the hybrid functional HSE6 optimized with norm-conserving pseudopotentials. The calculated vibrational structure allows for the symmetry assignment of key Raman modes in terms of atomic movements, and the calculated frequency values are in good agreement with experiment. The solid-phase DFT calculations reveal that the N atoms of the triazine ring contribute mostly to the density of states at the Fermi level. In addition, we present and discuss the computed solid-phase heat of formation (215.9 kJ/mol) and molecular electrostatic potential surface of DTO and compare them to complementary materials.
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Affiliation(s)
- Iskander G Batyrev
- Army Combat Capabilities Development Command (DEVCOM), Army Research Laboratory, Aberdeen Proving Ground, Maryland 21005, United States
| | - Edward F C Byrd
- Army Combat Capabilities Development Command (DEVCOM), Army Research Laboratory, Aberdeen Proving Ground, Maryland 21005, United States
| | - Rosario C Sausa
- Army Combat Capabilities Development Command (DEVCOM), Army Research Laboratory, Aberdeen Proving Ground, Maryland 21005, United States
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Major KJ, Sanghera JS, Farrell ME, Holthoff E, Pellegrino PM, Ewing KJ. Spectral Considerations for Standoff Infrared Detection of RDX on Reflective Aluminum. APPLIED SPECTROSCOPY 2022; 76:163-172. [PMID: 34643139 DOI: 10.1177/00037028211053865] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
This paper examines infrared spectroscopic effects for the standoff detection of an explosive material, hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), inkjet printed on an aluminum surface. Results of a spectroscopic study are described, using multiple optical setups. These setups were selected to explore how variations in the angles of incidence and collection from the surface of the material result in corresponding variations in the spectral signatures. The goal of these studies is to provide an understanding of these spectral changes since it affects standoff detection of hazardous materials on a reflective substrate. We demonstrate that variations in spectral effects are dependent on the relative surface concentration of the deposited RDX. We also show that it is reasonable to use spectroscopic data collected in a standard laboratory infrared spectrometer outfitted with a variable angle reflectometer set at 0° as reference spectra for data collected in a standoff configuration. These results are important to provide a systematic approach to understanding infrared (IR) spectra collection using standoff systems in the field, and to allow for comparison between such data, and data collected in the laboratory. Although the precise results are constrained to a specific material system (thin layers on a reflective substrate), the approach and general discussion provided are applicable to a broad range of IR standoff sensing techniques and applications.
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Affiliation(s)
- Kevin J Major
- Optical Sciences Division, US Naval Research Laboratory, Washington, DC, USA
| | | | - Mikella E Farrell
- United States Army Research Laboratory, RDRL-SEE-E, Adelphi, MD, USA
| | - Ellen Holthoff
- Office of the Deputy Assistant of the Army for Research and Technology, Arlington, VA, USA
| | - Paul M Pellegrino
- United States Army Research Laboratory, RDRL-SEE-E, Adelphi, MD, USA
| | - Kenneth J Ewing
- Optical Sciences Division, US Naval Research Laboratory, Washington, DC, USA
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Izvekov S, Rice BM. Bottom-up coarse-grain modeling of plasticity and nanoscale shear bands in α-RDX. J Chem Phys 2021; 155:064503. [PMID: 34391357 DOI: 10.1063/5.0057223] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Computationally inexpensive particle-based coarse-grained (CG) models are essential for use in molecular dynamics (MD) simulations of mesoscopically slow cooperative phenomena, such as plastic deformations in solids. Molecular crystals possessing complex symmetry present enormous practical challenges for particle-based coarse-graining at molecularly resolved scales, when each molecule is in a single-site representation, and beyond. Presently, there is no published pairwise non-bonded single-site CG potential that is able to predict the space group and structure of a molecular crystal. In this paper, we present a successful coarse-graining at a molecular level from first principles of an energetic crystal, hexahydro-1,3,5-trinitro-s-triazine (RDX) in the alpha phase, using the force-matching-based multiscale coarse-graining (MSCG/FM) approach. The new MSCG/FM model, which implements an optimal pair decomposition of the crystal Helmholtz free energy potential in molecular center-of-mass coordinates, was obtained by force-matching atomistic MD simulations of liquid, amorphous, and crystalline states and in a wide range of pressures (up to 20 GPa). The MSCG/FM potentials for different pressures underwent top-down optimization to fine-tune the mechanical and thermodynamic properties, followed by consolidation into a transferable density-dependent model referred to as RDX-TC-DD (RDX True-Crystal Density-Dependent). The RDX-TC-DD model predicts accurately the crystal structure of α-RDX at room conditions and reproduces the atomistic reference system under isothermal (300 K) hydrostatic compression up to 20 GPa, in particular, the Pbca symmetry of α-RDX in the elastic regime. The RDX-TC-DD model was then used to simulate the plastic response of uniaxially ([100]) compressed α-RDX resulting in nanoscale shear banding, a key mechanism for plastic deformation and defect-free detonation initiation proposed for many molecular crystalline explosives. Additionally, a comparative analysis of the effect of core-softening of the RDX-TC-DD potential and the degree of molecular rigidity in the all-atom treatment suggests a stress-induced short-range softening of the effective intermolecular interaction as a fundamental cause of plastic instability in α-RDX. The reported RDX-TC-DD model and overall workflow to develop it open up possibilities to perform high quality simulation studies of molecular energetic materials under thermal and mechanical stimuli, including extreme conditions.
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Affiliation(s)
- Sergei Izvekov
- Weapons and Materials Research Directorate, U.S. Army DEVCOM Army Research Laboratory, Aberdeen Proving Ground, Maryland 21005, USA
| | - Betsy M Rice
- Weapons and Materials Research Directorate, U.S. Army DEVCOM Army Research Laboratory, Aberdeen Proving Ground, Maryland 21005, USA
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8
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Ramachandran K, Kumari A, Nath Acharyya J, Chaudhary AK. Study of photo induced charge transfer mechanism of PEDOT with nitro groups of RDX, HMX and TNT explosives using anti-stokes and stokes Raman lines ratios. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2021; 251:119360. [PMID: 33453599 DOI: 10.1016/j.saa.2020.119360] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2020] [Revised: 11/25/2020] [Accepted: 12/16/2020] [Indexed: 06/12/2023]
Abstract
The paper reports the charge transfer mechanism between poly (3,4-ethylenedioxythiophene) (PEDOT) and high energy materials such as RDX, HMX and TNT, respectively in terms of ratios of anti-stokes (AS) and stokes(S) Raman lines of NO2 bands. Generally it works as an effective sensing medium for the detection of explosives when mixed in an equal proportion and are subjected to 532 nm wavelength without any chemical treatment [1]. The pristine PEDOT is less sensitive to 532 nm wavelength (2.33 eV) but influences the Raman S and AS lines of explosives in the mixture. The study also reveals that a small quantity (one milligram) of PEDOT is sufficient to initiate the positive charge transfer mechanism between its oxidized state to the lone pairs of electrons on the oxygen atoms of the nitro group of the explosive molecules. Consequently, the intensity of the Raman spectra of RDX, HMX and TNT is dropped by an order of 22.5, 11.45 and 17.2 times, respectively along with the shift of the NO2 vibrational modes. It is also attributed to Photon-electron-phonon interaction. Finally, we have estimated the reduced mass of the functional group to ascertain the force constant and the intensity ratios of AS /S lines to confirm the charge transfer mechanism. The effect of charge transfer mechanism is also reflected in drastic change in transmission /absorption characteristics of FTIR spectra of same PEDOT and explosive mixtures.
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Affiliation(s)
- K Ramachandran
- Advanced Centre for Research in High Energy Materials, University of Hyderabad, Telangana, 500046, India; National Center for Physical Acoustics, The University of Mississippi, 145 Hill Drive University, MS 38677- 1848, United States
| | - Archana Kumari
- Advanced Centre for Research in High Energy Materials, University of Hyderabad, Telangana, 500046, India
| | - Jitendra Nath Acharyya
- Advanced Centre for Research in High Energy Materials, University of Hyderabad, Telangana, 500046, India; Department of Physics, Indian Institute of Technology, Hauz Khas, Delhi 110016, India
| | - A K Chaudhary
- Advanced Centre for Research in High Energy Materials, University of Hyderabad, Telangana, 500046, India.
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9
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Zhang S, Jia H, Song M, Shen H, Dongfei L, Haibo L. Raman spectroscopy study of acetonitrile at low temperature. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2021; 246:119065. [PMID: 33096448 DOI: 10.1016/j.saa.2020.119065] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2020] [Revised: 10/01/2020] [Accepted: 10/06/2020] [Indexed: 06/11/2023]
Abstract
We report the low-temperature studies of liquid CH3CN by Raman spectral measurements at ambient pressure with decreasing the temperature from 20 to -196 °C. Detailed internal modes especially the lattice modes analysis revealed that the structural phase transitions of acetonitrile from liquid to solid phase β and solid phase β to solid phase α were occurring at -50 and -60 °C, respectively. Further, the Fermi resonance parameters between the fundamental ν2 and combination (ν3 + ν4) of CH3CN at different temperatures were calculated based on the Bertran's equations. It is found that the Fermi resonance parameters as a function of temperature become discontinued at -50 and -60 °C, which coincides with discontinuities observed in the Raman shifts of CH3CN at -50 and -60 °C. The results suggest that the Fermi resonance parameters could be used as an indicator to assess the structural phase transition for CH3CN under low temperature.
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Affiliation(s)
- Shuo Zhang
- Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education, Jilin Normal University, Siping 136000, Jilin Province, People's Republic of China
| | - Hongsheng Jia
- Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education, Jilin Normal University, Siping 136000, Jilin Province, People's Republic of China
| | - Mingxing Song
- College of Information and Technology, Jilin Normal University, Siping 136000, Jilin Province, People's Republic of China
| | - He Shen
- Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education, Jilin Normal University, Siping 136000, Jilin Province, People's Republic of China
| | - Li Dongfei
- Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education, Jilin Normal University, Siping 136000, Jilin Province, People's Republic of China.
| | - Li Haibo
- Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education, Jilin Normal University, Siping 136000, Jilin Province, People's Republic of China.
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10
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Major KJ, Sanghera JS, Aggarwal ID, Farrell ME, Holthoff EL, Pellegrino PM, Ewing KJ. Demonstration of a Human Color Vision Mimic in the Infrared. Anal Chem 2019; 91:14058-14065. [PMID: 31552733 DOI: 10.1021/acs.analchem.9b03749] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Color vision results from the interaction of retinal photopigments with reflected or transmitted visible light. The International Commission on Illumination (CIE) developed the CIE color-matching chart, which separates colors on the basis of the interaction of their spectral profiles with three retinal photopigments in the human eye. We report the development of an infrared chromaticity (CIE-IR) chart, which mimics the CIE chart, in order to discriminate between different chemicals on the basis of the interactions of their IR signatures with three different IR optical filters, instead of the retinal photopigments in the human eye. Our results demonstrate that the CIE-IR chart enables separation of different classes of chemicals, as the visible CIE chart does with color, except for those in the IR spectral region. Such results clearly show that the biomimetic sensing method based on human color vision is in fact a true analogue to color vision and that the proposed CIE-IR chart can be used as a classification method unique to this biomimetic sensing modality.
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Affiliation(s)
- Kevin J Major
- Optical Sciences Division , United States Naval Research Laboratory , Washington, DC 20375 , United States
| | - Jasbinder S Sanghera
- Optical Sciences Division , United States Naval Research Laboratory , Washington, DC 20375 , United States
| | - Ishwar D Aggarwal
- Department of Physics and Optical Science , University of North Carolina at Charlotte , Charlotte , North Carolina 28223 , United States.,Key W Corporation , Hanover , Maryland 21076 , United States
| | - Mikella E Farrell
- RDRL-SEE-E , United States Army Research Laboratory , Adelphi , Maryland 20783 , United States
| | - Ellen L Holthoff
- RDRL-SEE-E , United States Army Research Laboratory , Adelphi , Maryland 20783 , United States
| | - Paul M Pellegrino
- RDRL-SEE-E , United States Army Research Laboratory , Adelphi , Maryland 20783 , United States
| | - Kenneth J Ewing
- Optical Sciences Division , United States Naval Research Laboratory , Washington, DC 20375 , United States
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Pacheco-Londoño LC, Ruiz-Caballero JL, Ramírez-Cedeño ML, Infante-Castillo R, Gálan-Freyle NJ, Hernández-Rivera SP. Surface Persistence of Trace Level Deposits of Highly Energetic Materials. Molecules 2019; 24:molecules24193494. [PMID: 31561514 PMCID: PMC6804148 DOI: 10.3390/molecules24193494] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Revised: 09/12/2019] [Accepted: 09/16/2019] [Indexed: 12/05/2022] Open
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.
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Affiliation(s)
- Leonardo C Pacheco-Londoño
- 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.
- School of Basic and Biomedical Sciences, Universidad Simón Bolívar, Barranquilla, 080020 Atlantico, Colombia.
| | - José L Ruiz-Caballero
- 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.
- Joseph Smith & Sons Inc., Capitol Heights, MD 20743, USA.
- Department of Chemistry and Biochemistry, George Mason University, Fairfax, VA 22030, USA.
| | - Michael L Ramírez-Cedeño
- 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 J Gálan-Freyle
- 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.
- School of Basic and Biomedical Sciences, Universidad Simón Bolívar, Barranquilla, 080020 Atlantico, Colombia.
| | - Samuel P Hernández-Rivera
- 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.
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Brady JJ, Argirakis BL, Gordon AD, Lareau RT, Smith BT. Polymorphic Phase Control of RDX-Based Explosives. APPLIED SPECTROSCOPY 2018; 72:28-36. [PMID: 28537423 DOI: 10.1177/0003702817712259] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The polymorphic phase of 1,3,5-trinitro-1,3,5-triazine (RDX) was examined as a function of mass loading, solvent, and sample deposition technique. When RDX was deposited at a high mass loading, the vibrational modes in the obtained Raman spectra were indicative of concomitant polymorphism as both the α-RDX and β-RDX phases were present. At low mass loadings, only β-RDX was observed regardless of solvent when using the drop cast crystallization method. However, α-RDX (the thermodynamically stable polymorphic phase observed with visible quantities of the explosive) was observed when RDX deposits were dry transferred. Observation of α-RDX was independent of the initial mass loading or the initial deposition solvent when using the dry transfer methodology. These data indicate that the use of the dry transfer preparation method can be used to successfully prepare RDX-based test articles with the α-RDX phase regardless of the solvent used to initially dissolve the RDX, the initial deposition technique, or the mass loading.
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Affiliation(s)
- John J Brady
- 1 Transportation Security Laboratory, William J. Hughes Technical Center, Atlantic City, NJ, USA
| | - Brittney L Argirakis
- 1 Transportation Security Laboratory, William J. Hughes Technical Center, Atlantic City, NJ, USA
- 2 Penn State University, University Park, PA, USA
| | - Alexander D Gordon
- 1 Transportation Security Laboratory, William J. Hughes Technical Center, Atlantic City, NJ, USA
- 3 Signature Science, LLC, Egg Harbor Township, NJ, USA
| | - Richard T Lareau
- 1 Transportation Security Laboratory, William J. Hughes Technical Center, Atlantic City, NJ, USA
| | - Barry T Smith
- 1 Transportation Security Laboratory, William J. Hughes Technical Center, Atlantic City, NJ, USA
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Gao C, Zhang X, Zhang C, Sui Z, Hou M, Dai R, Wang Z, Zheng X, Zhang Z. Effect of pressure gradient and new phases for 1,3,5-trinitrohexahydro-s-triazine (RDX) under high pressures. Phys Chem Chem Phys 2018; 20:14374-14383. [PMID: 29770413 DOI: 10.1039/c8cp01192c] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Herein, pressure-induced phase transitions of RDX up to 50 GPa were systematically studied under different compression conditions.
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Affiliation(s)
- Chan Gao
- Department of Physics
- University of Science and Technology of China
- Hefei
- China
| | - Xueyong Zhang
- Department of Chemistry
- Purdue University
- West Lafayette
- USA
| | - Chuanchao Zhang
- Research Center of Laser Fusion
- China Academy of Engineering Physics
- Mianyang
- China
| | - Zhilei Sui
- Institute of Fluid Physics
- China Academy of Engineering Physics
- Mianyang
- China
| | - Meng Hou
- Department of Physics
- University of Science and Technology of China
- Hefei
- China
| | - Rucheng Dai
- The Centre for Physical Experiments
- University of Science and Technology of China
- Hefei
- China
| | - Zhongping Wang
- The Centre for Physical Experiments
- University of Science and Technology of China
- Hefei
- China
| | - Xianxu Zheng
- Institute of Fluid Physics
- China Academy of Engineering Physics
- Mianyang
- China
| | - Zengming Zhang
- The Centre for Physical Experiments
- University of Science and Technology of China
- Hefei
- China
- Key Laboratory of Strongly-Coupled Quantum Matter Physics
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14
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Ruiz-Caballero JL, Aparicio-Bolaño JA, Figueroa-Navedo AM, Pacheco-Londoño LC, Hernandez-Rivera SP. Optical Properties of β-RDX Thin Films Deposited on Gold and Stainless Steel Substrates Calculated from Reflection-Absorption Infrared Spectra. APPLIED SPECTROSCOPY 2017; 71:1990-2000. [PMID: 28537428 DOI: 10.1177/0003702817710248] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The optical properties for crystalline films of the highly energetic material (HEM) hexahydro-1,3,5-trinitro-s-triazine, which is also known as RDX, deposited on gold (Au) and stainless steel (SS) substrates are presented. RDX has two important stable conformational polymorphs at room temperature: α-RDX and β-RDX. The optical properties obtained in the present work correspond to thin film samples of predominantly β-RDX polymorph. The infrared spectroscopic intensities measured showed significant differences in the β-RDX crystalline films deposited on the two substrates with respect to the calculated real part of refractive index. The β-RDX/Au crystalline films have a high dynamic response, which is characterized by the asymmetric stretching mode of the axial nitro groups, whereas for the β-RDX/SS crystalline films, the dynamic response was mediated by the -N-NO2 symmetric stretch mode. This result provides an idea of how the electric field vector propagates through the β-RDX crystalline films deposited on the two substrates.
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Affiliation(s)
- José L Ruiz-Caballero
- 1 ALERT DHS Center of Excellence for Explosives Research, Department of Chemistry, University of Puerto Rico, Mayagüez, PR, USA
| | | | - Amanda M Figueroa-Navedo
- 1 ALERT DHS Center of Excellence for Explosives Research, Department of Chemistry, University of Puerto Rico, Mayagüez, PR, USA
| | - Leonardo C Pacheco-Londoño
- 1 ALERT DHS Center of Excellence for Explosives Research, Department of Chemistry, University of Puerto Rico, Mayagüez, PR, USA
- 3 School of Basic and Biomedical Sciences, Universidad Simón Bolívar, Barranquilla, Colombia
| | - Samuel P Hernandez-Rivera
- 1 ALERT DHS Center of Excellence for Explosives Research, Department of Chemistry, University of Puerto Rico, Mayagüez, PR, USA
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15
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Pal A, Meunier V, Picu CR. Investigating Orientational Defects in Energetic Material RDX Using First-Principles Calculations. J Phys Chem A 2016; 120:1917-24. [PMID: 26943238 DOI: 10.1021/acs.jpca.6b00574] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Orientational defects are molecular-scale point defects consisting of misaligned sterically trapped molecules. Such defects have been predicted in α-RDX using empirical force fields. These calculations indicate that their concentration should be higher than that of vacancies. In this study we confirm the stability of a family of four orientational defects in α-RDX using first-principles calculations and evaluate their formation energies and annealing barrier heights. The charge density distribution in the defective molecules is evaluated and it is shown that all four orientational defects exhibit some level of charge reduction at the midpoint of the N-N bond, which has been previously related to the sensitivity to initiation of the material. We also evaluate the vibrational spectrum of the crystal containing orientational defects and observe band splitting relative to the perfect crystal case. This may assist the experimental identification of such defects by Raman spectroscopy.
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Affiliation(s)
- Anirban Pal
- Department of Mechanical, Aerospace and Nuclear Engineering and ‡Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute , Troy, New York 12180, United States
| | - Vincent Meunier
- Department of Mechanical, Aerospace and Nuclear Engineering and ‡Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute , Troy, New York 12180, United States
| | - Catalin R Picu
- Department of Mechanical, Aerospace and Nuclear Engineering and ‡Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute , Troy, New York 12180, United States
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16
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Subramanian G, Mathew N, Leiding J. A generalized force-modified potential energy surface for mechanochemical simulations. J Chem Phys 2015; 143:134109. [PMID: 26450294 DOI: 10.1063/1.4932103] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Gopinath Subramanian
- School of Polymers and High Performance Materials, University of Southern Mississippi, Hattiesburg, Mississippi 39402, USA
| | - Nithin Mathew
- Department of Chemistry, University of Missouri-Columbia, Columbia, Missouri 65211, USA
| | - Jeff Leiding
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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17
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Gares KL, Bykov SV, Brinzer T, Asher SA. Solution and Solid Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) Ultraviolet (UV) 229 nm Photochemistry. APPLIED SPECTROSCOPY 2015; 69:545-554. [PMID: 25812170 DOI: 10.1366/14-07622] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We measured the 229 nm deep-ultraviolet resonance Raman (DUVRR) spectra of solution and solid-state hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). We also examined the photochemistry of RDX both in solution and solid states. RDX quickly photodegrades with a solution quantum yield of φ ~ 0.35 as measured by high-performance liquid chromatography (HPLC). New spectral features form over time during the photolysis of RDX, indicating photoproduct formation. The photoproduct(s) show stable DUVRR spectra at later irradiation times that allow standoff detection. In the solution-state photolysis, nitrate is a photoproduct that can be used as a signature for detection of RDX even after photolysis. We used high-performance liquid chromatography-high-resolution mass spectrometry (HPLC-HRMS) and gas chromatography mass spectrometry (GCMS) to determine some of the major solution-state photoproducts. X-ray photoelectron spectroscopy (XPS) was also used to determine photoproducts formed during solid-state RDX photolysis.
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18
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Galán-Freyle NJ, Pacheco-Londoño LC, Figueroa-Navedo AM, Hernandez-Rivera SP. Standoff detection of highly energetic materials using laser-induced thermal excitation of infrared emission. APPLIED SPECTROSCOPY 2015; 69:535-544. [PMID: 25811843 DOI: 10.1366/14-07501] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
A laser-mediated methodology for standoff infrared detection of threat chemicals is described in this article. Laser-induced thermal emissions (LITE) from vibrationally excited residue of highly energetic material (HEM) deposited on substrates were detected remotely. Telescope-based Fourier transform infrared (FT-IR) spectroscopy measurements were carried out on substrates containing small amounts of HEM at surface concentrations of 5-200 μg/cm(2). Target substrates of various thicknesses were heated remotely using a carbon dioxide laser, and their mid-infrared (mid-IR), thermally stimulated emission spectra were recorded after heating. The telescope was configured from reflective optical elements to minimize emission losses in the mid-IR frequencies. Spectral replicas were acquired at distances from 4 to 64 m using an FT-IR interferometer at 4 cm(-1) resolution. The laser power, laser exposure times, and acquisition time of the FT-IR interferometer were adjusted to improve the detection and identification of samples. The advantages of increasing the thermal emission were easily observed in the results. The signal intensities were proportional to the thickness of the coated surface (a function of the surface concentration) as well as the laser power and laser exposure time. The limits of detection obtained for the HEM studied were 140-21 μg/cm(2) at 4 m. Detection was achieved at 64 m for a surface concentration of 200 μg/cm(2).
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19
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Pal A, Picu RC. Rotational defects in cyclotrimethylene trinitramine (RDX) crystals. J Chem Phys 2014; 140:044512. [PMID: 25669560 DOI: 10.1063/1.4862997] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Cyclotrimethylene trinitramine (RDX) crystalizes in the orthorhombic α-phase at the ambient pressure and temperature. In principle, the point defects commonly found in monatomic crystals, such as vacancies and interstitials, may exist in RDX as well. However, in molecular crystals one encounters additional point defects associated with the distortion of the molecules. A set of rotational defects are described in this article. These are molecules which are located in the proper positions in the crystal but are rotated relative to the molecules in the perfect crystal, and their ring is slightly puckered. The energetic barriers for defect formation and for their annealing back to the perfect crystal configuration are computed using an atomistic model. It is shown that the formation energy of rotational defects is smaller than the vacancy formation energy. Such defects are identified in the cores of dislocations in RDX and hence their concentration in the crystal is expected to increase during plastic deformation. The importance of such point defects is related to their role in phonon scattering and in dislocation-mediated plastic deformation.
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Affiliation(s)
- A Pal
- Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180, USA
| | - R C Picu
- Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180, USA
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20
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Fountain AW, Christesen SD, Moon RP, Guicheteau JA, Emmons ED. Recent advances and remaining challenges for the spectroscopic detection of explosive threats. APPLIED SPECTROSCOPY 2014; 68:795-811. [PMID: 25061781 DOI: 10.1366/14-07560] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
In 2010, the U.S. Army initiated a program through the Edgewood Chemical Biological Center to identify viable spectroscopic signatures of explosives and initiate environmental persistence, fate, and transport studies for trace residues. These studies were ultimately designed to integrate these signatures into algorithms and experimentally evaluate sensor performance for explosives and precursor materials in existing chemical point and standoff detection systems. Accurate and validated optical cross sections and signatures are critical in benchmarking spectroscopic-based sensors. This program has provided important information for the scientists and engineers currently developing trace-detection solutions to the homemade explosive problem. With this information, the sensitivity of spectroscopic methods for explosives detection can now be quantitatively evaluated before the sensor is deployed and tested.
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Affiliation(s)
- Augustus W Fountain
- Research and Technology Directorate, Edgewood Chemical Biological Center, Aberdeen Proving Ground, Aberdeen, Md 21010-5424 Usa
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21
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Nabiev SS, Stavrovskii DB, Palkina LA, Zbarskii VL, Yudin NV, Vaks VL, Domracheva EG, Chernyaeva MB. Spectrochemical properties of some explosives in the vapor state. RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY B 2013. [DOI: 10.1134/s1990793113050084] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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22
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Design Considerations for a Portable Raman Probe Spectrometer for Field Forensics. ACTA ACUST UNITED AC 2012. [DOI: 10.1155/2012/938407] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Raman spectroscopy has been shown to be a viable method for explosives detection. Currently most forensic Raman systems are either large, powerful instruments for laboratory experiments or handheld instruments for in situ point detection. We have chosen to examine the performance of certain benchtop Raman probe systems with the goal of developing an inexpensive, portable system that could be used to operate in a field forensics laboratory to examine explosives-related residues or samples. To this end, a rugged, low distortion line imaging dispersive Raman spectrograph was configured to work at 830 nm laser excitation and was used to determine whether the composition of thin films of plastic explosives or small (e.g., ≤10 μm) particles of RDX or other explosives or oxidizers can be detected, identified, and quantified in the field. With 300 mW excitation energy, concentrations of RDX and PETN can be detected and reconstructed in the case of thin Semtex smears, but further work is needed to push detection limits of areal dosages to the ~1 μg/cm2 level. We describe the performance of several probe/spectrograph combinations and show preliminary data for particle detection, calibration and detection linearity for mixed compounds, and so forth.
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23
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Liu Y, Zhang L, Wang G, Wang L, Gong X. High-pressure studies on azido-tetrazole chain–ring conversion in crystalline 2-azido-4,6-dichloro-1,3,5-triazine. Theor Chem Acc 2012. [DOI: 10.1007/s00214-012-1256-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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24
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Emmons ED, Farrell ME, Holthoff EL, Tripathi A, Green N, Moon RP, Guicheteau JA, Christesen SD, Pellegrino PM, Fountain AW. Characterization of polymorphic states in energetic samples of 1,3,5-trinitro-1,3,5-triazine (RDX) fabricated using drop-on-demand inkjet technology. APPLIED SPECTROSCOPY 2012; 66:628-635. [PMID: 22732532 DOI: 10.1366/12-06608] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The United States Army and the first responder community are evaluating optical detection systems for the trace detection of hazardous energetic materials. Fielded detection systems must be evaluated with the appropriate material concentrations to accurately identify the residue in theater. Trace levels of energetic materials have been observed in mutable polymorphic phases and, therefore, the systems being evaluated must be able to detect and accurately identify variant sample phases observed in spectral data. In this work, we report on the novel application of drop-on-demand technology for the fabrication of standardized trace 1,3,5-trinitro-1,3,5-triazine (RDX) samples. The drop-on-demand sample fabrication technique is compared both visually and spectrally to the more commonly used drop-and-dry technique. As the drop-on-demand technique allows for the fabrication of trace level hazard materials, concerted efforts focused on characterization of the polymorphic phase changes observed with low concentrations of RDX commonly used in drop-on-demand processing. This information is important when evaluating optical detection technologies using samples prepared with a drop-on-demand inkjet system, as the technology may be "trained" to detect the common bulk α phase of the explosive based on its spectral features but fall short in positively detecting a trace quantity of RDX (β-phase). We report the polymorphic shifts observed between α- and β-phases of this energetic material and discuss the conditions leading to the favoring of one phase over the other.
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Affiliation(s)
- Erik D Emmons
- Science Applications International Corporation, Gunpowder Branch, Aberdeen Proving Ground, Maryland 21010-5424, USA
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25
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Emmons ED, Guicheteau JA, Fountain AW, Christesen SD. Comparison of visible and near-infrared Raman cross-sections of explosives in solution and in the solid state. APPLIED SPECTROSCOPY 2012; 66:636-643. [PMID: 22732533 DOI: 10.1366/11-06549] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Raman cross-sections of explosives in solution and in the solid state have been measured using visible and near-infrared excitation via secondary calibration. These measurements are valuable for both fundamental scientific purposes and applications in the standoff detection of explosives. The explosive compounds RDX, HMX, TNT, 2,4-DNT, 2,6-DNT, and ammonium nitrate were measured using discrete excitation wavelengths ranging from 532 nm to 785 nm. A comparison of the spectral features and cross-sections between the solid state and solution was performed. Comparison is also made to cross-sections measured with deep ultraviolet excitation.
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Affiliation(s)
- Erik D Emmons
- Science Applications International Corporation, Gunpowder Branch, Aberdeen Proving Ground, Maryland 21010-5424, USA
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26
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Mathew N, Picu RC. Molecular conformational stability in cyclotrimethylene trinitramine crystals. J Chem Phys 2011; 135:024510. [DOI: 10.1063/1.3609769] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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