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Singh SK, Vuppuluri V, Son SF, Kaiser RI. Investigating the Photochemical Decomposition of Solid 1,3,5-Trinitro-1,3,5-triazinane (RDX). J Phys Chem A 2020; 124:6801-6823. [DOI: 10.1021/acs.jpca.0c05726] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Santosh K. Singh
- Department of Chemistry, University of Hawaii, Honolulu, Hawaii 96822, United States
- W. M. Keck Research Laboratory in Astrochemistry, University of Hawaii, Honolulu, Hawaii 96822, United States
| | - Vasant Vuppuluri
- Mechanical Engineering, Purdue Energetics Research Center, Purdue University, West Lafayette, Indiana 47907, United States
| | - Steven F. Son
- Mechanical Engineering, Purdue Energetics Research Center, Purdue University, West Lafayette, Indiana 47907, United States
| | - Ralf I. Kaiser
- Department of Chemistry, University of Hawaii, Honolulu, Hawaii 96822, United States
- W. M. Keck Research Laboratory in Astrochemistry, University of Hawaii, Honolulu, Hawaii 96822, United States
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2
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Singh SK, La Jeunesse J, Vuppuluri V, Son SF, Sun B, Chen Y, Chang AHH, Mebel AM, Kaiser RI. The Elusive Ketene (H
2
CCO) Channel in the Infrared Multiphoton Dissociation of Solid 1,3,5‐Trinitro‐1,3,5‐Triazinane (RDX). Chemphyschem 2020; 21:837-842. [DOI: 10.1002/cphc.201901202] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 02/18/2020] [Indexed: 11/05/2022]
Affiliation(s)
- Santosh K. Singh
- Department of Chemistry W. M. Keck Research Laboratory in AstrochemistryUniversity of Hawaii Honolulu HI 96822 HI USA
| | - Jesse La Jeunesse
- Department of Chemistry W. M. Keck Research Laboratory in AstrochemistryUniversity of Hawaii Honolulu HI 96822 HI USA
| | - Vasant Vuppuluri
- Mechanical Engineering Purdue Energetics Research CenterPurdue University West Lafayette IN 47907 USA
| | - Steven F. Son
- Mechanical Engineering Purdue Energetics Research CenterPurdue University West Lafayette IN 47907 USA
| | - Bing‐Jian Sun
- Department of ChemistryNational Dong Hwa University Shoufeng, Hualien 974 Taiwan
| | - Yue‐Lin Chen
- Department of ChemistryNational Dong Hwa University Shoufeng, Hualien 974 Taiwan
| | - Agnes H. H. Chang
- Department of ChemistryNational Dong Hwa University Shoufeng, Hualien 974 Taiwan
| | - Alexander M. Mebel
- Department of Chemistry and BiochemistryFlorida International University Miami, Florida 33199 USA
| | - Ralf I. Kaiser
- Department of Chemistry W. M. Keck Research Laboratory in AstrochemistryUniversity of Hawaii Honolulu HI 96822 HI USA
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3
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Nelson TR, White AJ, Bjorgaard JA, Sifain AE, Zhang Y, Nebgen B, Fernandez-Alberti S, Mozyrsky D, Roitberg AE, Tretiak S. Non-adiabatic Excited-State Molecular Dynamics: Theory and Applications for Modeling Photophysics in Extended Molecular Materials. Chem Rev 2020; 120:2215-2287. [PMID: 32040312 DOI: 10.1021/acs.chemrev.9b00447] [Citation(s) in RCA: 179] [Impact Index Per Article: 44.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Optically active molecular materials, such as organic conjugated polymers and biological systems, are characterized by strong coupling between electronic and vibrational degrees of freedom. Typically, simulations must go beyond the Born-Oppenheimer approximation to account for non-adiabatic coupling between excited states. Indeed, non-adiabatic dynamics is commonly associated with exciton dynamics and photophysics involving charge and energy transfer, as well as exciton dissociation and charge recombination. Understanding the photoinduced dynamics in such materials is vital to providing an accurate description of exciton formation, evolution, and decay. This interdisciplinary field has matured significantly over the past decades. Formulation of new theoretical frameworks, development of more efficient and accurate computational algorithms, and evolution of high-performance computer hardware has extended these simulations to very large molecular systems with hundreds of atoms, including numerous studies of organic semiconductors and biomolecules. In this Review, we will describe recent theoretical advances including treatment of electronic decoherence in surface-hopping methods, the role of solvent effects, trivial unavoided crossings, analysis of data based on transition densities, and efficient computational implementations of these numerical methods. We also emphasize newly developed semiclassical approaches, based on the Gaussian approximation, which retain phase and width information to account for significant decoherence and interference effects while maintaining the high efficiency of surface-hopping approaches. The above developments have been employed to successfully describe photophysics in a variety of molecular materials.
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Affiliation(s)
- Tammie R Nelson
- Theoretical Division , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
| | - Alexander J White
- Theoretical Division , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
| | - Josiah A Bjorgaard
- Theoretical Division , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
| | - Andrew E Sifain
- Theoretical Division , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States.,U.S. Army Research Laboratory , Aberdeen Proving Ground , Maryland 21005 , United States
| | - Yu Zhang
- Theoretical Division , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
| | - Benjamin Nebgen
- Theoretical Division , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
| | | | - Dmitry Mozyrsky
- Theoretical Division , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
| | - Adrian E Roitberg
- Department of Chemistry , University of Florida , Gainesville , Florida 32611 , United States
| | - Sergei Tretiak
- Theoretical Division , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
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4
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Singh SK, Zhu C, Vuppuluri V, Son SF, Kaiser RI. Probing the Reaction Mechanisms Involved in the Decomposition of Solid 1,3,5-Trinitro-1,3,5-triazinane by Energetic Electrons. J Phys Chem A 2019; 123:9479-9497. [PMID: 31589046 DOI: 10.1021/acs.jpca.9b08695] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The decomposition mechanisms of 1,3,5-trinitro-1,3,5-triazinane (RDX) have been explored over the past decades, but as of now, a complete picture on these pathways has not yet emerged, as evident from the discrepancies in proposed reaction mechanisms and the critical lack of products and intermediates observed experimentally. This study exploited a surface science machine to investigate the decomposition of solid-phase RDX by energetic electrons at a temperature of 5 K. The products formed during irradiation were monitored online and in situ via infrared and UV-vis spectroscopy, and products subliming in the temperature programmed desorption phase were probed with a reflectron time-of-flight mass spectrometer coupled with soft photoionization at 10.49 eV (ReTOF-MS-PI). Infrared spectroscopy revealed the formation of water (H2O), carbon dioxide (CO2), dinitrogen oxide (N2O), nitrogen monoxide (NO), formaldehyde (H2CO), nitrous acid (HONO), and nitrogen dioxide (NO2). ReTOF-MS-PI identified 38 cyclic and acyclic products arranged into, for example, dinitro, mononitro, mononitroso, nitro-nitroso, and amines species. Among these molecules, 21 products such as N-methylnitrous amide (CH4N2O), 1,3,5-triazinane (C3H9N3), and N-(aminomethyl)methanediamine (C2H9N3) were detected for the first time in laboratory experiments; mechanisms based on the gas phase and condensed phase calculations were exploited to rationalize the formation of the observed products. The present studies reveal a rich, unprecedented chemistry in the condensed phase decomposition of RDX, which is significantly more complex than the unimolecular gas phase decomposition of RDX, thus leading us closer to an understanding of the decomposition chemistry of nitramine-based explosives.
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Affiliation(s)
| | | | - Vasant Vuppuluri
- Mechanical Engineering, Purdue Energetics Research Center , Purdue University , 500 Allison Road , West Lafayette , Indiana 47907-2088 , United States
| | - Steven F Son
- Mechanical Engineering, Purdue Energetics Research Center , Purdue University , 500 Allison Road , West Lafayette , Indiana 47907-2088 , United States
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5
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Ampadu Boateng D, Gutsev GL, Jena P, Tibbetts KM. Dissociation dynamics of 3- and 4-nitrotoluene radical cations: Coherently driven C–NO2bond homolysis. J Chem Phys 2018; 148:134305. [DOI: 10.1063/1.5024892] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Derrick Ampadu Boateng
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, USA
| | - Gennady L. Gutsev
- Department of Physics, Florida A&M University, Tallahassee, Florida 32307, USA
| | - Puru Jena
- Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284, USA
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6
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Yu G, Zeng Y, Guo W, Wu H, Zhu G, Zheng Z, Zheng X, Song Y, Yang Y. Visualizing Intramolecular Vibrational Redistribution in Cyclotrimethylene Trinitramine (RDX) Crystals by Multiplex Coherent Anti-Stokes Raman Scattering. J Phys Chem A 2017; 121:2565-2571. [PMID: 28319388 DOI: 10.1021/acs.jpca.7b00069] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The femtosecond time-resolved multiplex coherent anti-Stokes Raman scattering (CARS) technique has been performed to investigate intramolecular vibrational redistribution (IVR) through vibrational couplings in 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX) molecules. In the multiplex CARS experiment, the supercontinuum (SC) was used as broad-band Stokes light to coherently and collectively excite multiple vibrational modes, and quantum beats arising from vibrational couplings among these modes were observed. The IVR of RDX is visualized by a topological graph of these vibrational couplings, and with analysis of the topological graph, two vibrational modes, both of which are assigned to ring bending, are confirmed to have coupling interactions with most of the other vibrational modes and are considered to have a tendency of energy transfer with these vibrational modes. We suggest that the mode at 466 cm-1 is a portal of energy transfer from outside to inside of the RDX molecule and the mode at 672 cm-1 is an important transit point of energy transfer in the IVR.
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Affiliation(s)
- Guoyang Yu
- National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, China Academy of Engineering Physics , Mianyang 621900, People's Republic of China
| | - Yangyang Zeng
- National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, China Academy of Engineering Physics , Mianyang 621900, People's Republic of China
| | - Wencan Guo
- National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, China Academy of Engineering Physics , Mianyang 621900, People's Republic of China
| | - Honglin Wu
- National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, China Academy of Engineering Physics , Mianyang 621900, People's Republic of China
| | - Gangbei Zhu
- National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, China Academy of Engineering Physics , Mianyang 621900, People's Republic of China
| | - Zhaoyang Zheng
- National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, China Academy of Engineering Physics , Mianyang 621900, People's Republic of China
| | - Xianxu Zheng
- National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, China Academy of Engineering Physics , Mianyang 621900, People's Republic of China
| | - Yunfei Song
- National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, China Academy of Engineering Physics , Mianyang 621900, People's Republic of China
| | - Yanqiang Yang
- National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, China Academy of Engineering Physics , Mianyang 621900, People's Republic of China
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7
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Yuan B, Bernstein ER. Initial mechanisms for the unimolecular decomposition of electronically excited bisfuroxan based energetic materials. J Chem Phys 2017; 146:014301. [DOI: 10.1063/1.4972259] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Bing Yuan
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872, USA
| | - Elliot R. Bernstein
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872, USA
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8
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Zeng Z, Bernstein ER. Photoelectron spectroscopy and density functional theory studies of N-rich energetic materials. J Chem Phys 2016; 145:164302. [DOI: 10.1063/1.4964944] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Affiliation(s)
- Zhen Zeng
- Department of Chemistry, NSF ERC for Extreme Ultraviolet Science and Technology, Colorado State University, Fort Collins, Colorado 80523, USA
| | - Elliot R. Bernstein
- Department of Chemistry, NSF ERC for Extreme Ultraviolet Science and Technology, Colorado State University, Fort Collins, Colorado 80523, USA
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9
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Akin FA. Ionisation energy, electron affinity, and mass spectral decomposition mechanisms of RDX isomers upon electron attachment and electron ionisation. Mol Phys 2016. [DOI: 10.1080/00268976.2016.1246759] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- F. A. Akin
- Department of Chemistry, Boğaziçi University, Bebek, Istanbul/Turkey
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10
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Akin F. Mass spectral decomposition mechanisms of RDX isomers upon electron attachment and electron ionisation: a DFT study of normal mode activation incorporating Duschinsky rotations. Mol Phys 2016. [DOI: 10.1080/00268976.2016.1229059] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- F.A. Akin
- Department of Chemistry, Boğaziçi University, Istanbul, Turkey
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11
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Yuan B, Bernstein ER. Initial mechanisms for the unimolecular decomposition of electronically excited nitrogen-rich energetic salts with tetrazole rings: (NH4)2BT and TAGzT. J Chem Phys 2016. [DOI: 10.1063/1.4960345] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Bing Yuan
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872, USA
| | - Elliot R. Bernstein
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872, USA
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12
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Yuan B, Bernstein ER. Initial mechanisms for the unimolecular decomposition of electronically excited nitrogen-rich energetic materials with tetrazole rings: 1-DTE, 5-DTE, BTA, and BTH. J Chem Phys 2016; 144:234302. [PMID: 27334157 DOI: 10.1063/1.4953552] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Bing Yuan
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872, USA
| | - Elliot R. Bernstein
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872, USA
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13
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Yuan B, Shin JW, Bernstein ER. Dynamics and fragmentation of van der Waals and hydrogen bonded cluster cations: (NH3)n and (NH3BH3)n ionized at 10.51 eV. J Chem Phys 2016; 144:144315. [DOI: 10.1063/1.4945624] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Bing Yuan
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872, USA
| | - Joong-Won Shin
- Division of Chemistry and Biological Sciences, Governors State University, University Park, Illinois 60484-0975, USA
| | - Elliot R. Bernstein
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872, USA
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14
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Nelson T, Bjorgaard J, Greenfield M, Bolme C, Brown K, McGrane S, Scharff RJ, Tretiak S. Ultrafast Photodissociation Dynamics of Nitromethane. J Phys Chem A 2016; 120:519-26. [DOI: 10.1021/acs.jpca.5b09776] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Tammie Nelson
- Los Alamos National Laboratory, Los
Alamos, New Mexico 87545, United States
| | - Josiah Bjorgaard
- Los Alamos National Laboratory, Los
Alamos, New Mexico 87545, United States
| | - Margo Greenfield
- Los Alamos National Laboratory, Los
Alamos, New Mexico 87545, United States
| | - Cindy Bolme
- Los Alamos National Laboratory, Los
Alamos, New Mexico 87545, United States
| | - Katie Brown
- Los Alamos National Laboratory, Los
Alamos, New Mexico 87545, United States
| | - Shawn McGrane
- Los Alamos National Laboratory, Los
Alamos, New Mexico 87545, United States
| | - R. Jason Scharff
- Los Alamos National Laboratory, Los
Alamos, New Mexico 87545, United States
| | - Sergei Tretiak
- Los Alamos National Laboratory, Los
Alamos, New Mexico 87545, United States
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15
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Molt RW, Watson T, Bazanté AP, Bartlett RJ, Richards NGJ. Gas phase RDX decomposition pathways using coupled cluster theory. Phys Chem Chem Phys 2016; 18:26069-26077. [DOI: 10.1039/c6cp05121a] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Electronic and free energy barriers for a series of gas-phase RDX decomposition mechanisms have been obtain using coupled cluster singles, doubles, and perturbative triples with complete basis set (CCSD(T)/CBS) electronic energies for MBPT(2)/cc-pVTZ structures.
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Affiliation(s)
- Robert W. Molt
- Department of Chemistry and Chemical Biology
- Indiana University-Purdue University Indianapolis
- Indianapolis
- USA
- School of Chemistry
| | - Thomas Watson
- Quantum Theory Project
- University of Florida
- Gainesville
- USA
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16
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Modesto-Costa L, Uhl E, Borges I. Water solvent effects using continuum and discrete models: The nitromethane molecule, CH3NO2. J Comput Chem 2015; 36:2260-9. [DOI: 10.1002/jcc.24208] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2015] [Revised: 08/04/2015] [Accepted: 08/30/2015] [Indexed: 11/10/2022]
Affiliation(s)
- Lucas Modesto-Costa
- Departamento De Química; Instituto Militar De Engenharia; Praça General Tibúrcio, 80 22290-270 Rio De Janeiro Brazil
| | - Elmar Uhl
- Programa De Pós-Graduação Em Engenharia De Defesa, Divisão de Ensino e Pesquisa; Instituto Militar De Engenharia; Praça General Tibúrcio, 80 Rio De Janeiro 22290-270 Brazil
| | - Itamar Borges
- Departamento De Química; Instituto Militar De Engenharia; Praça General Tibúrcio, 80 22290-270 Rio De Janeiro Brazil
- Programa De Pós-Graduação Em Engenharia De Defesa, Divisão de Ensino e Pesquisa; Instituto Militar De Engenharia; Praça General Tibúrcio, 80 Rio De Janeiro 22290-270 Brazil
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17
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Booth RS, Butler LJ. Thermal decomposition pathways for 1,1-diamino-2,2-dinitroethene (FOX-7). J Chem Phys 2015; 141:134315. [PMID: 25296814 DOI: 10.1063/1.4896165] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In this study, we computationally investigate the initial and subsequent steps in the chemical mechanism for the gas-phase thermal decomposition of 1,1-diamino-2,2-dinitroethene (FOX-7). We determine the key exothermic step in the gas-phase thermal decomposition of FOX-7 and explore the similarities and differences between FOX-7 and other geminal dinitro energetic materials. The calculations reveal a mechanism for NO loss involving a 3-member cyclic intermediate, rather than a nitro-nitrite isomerization, that occurs in the radical intermediates formed throughout the decomposition mechanism.
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Affiliation(s)
- Ryan S Booth
- The James Franck Institute and Department of Chemistry, University of Chicago, Chicago, Illinois 60637, USA
| | - Laurie J Butler
- The James Franck Institute and Department of Chemistry, University of Chicago, Chicago, Illinois 60637, USA
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18
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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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19
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Chung LW, Sameera WMC, Ramozzi R, Page AJ, Hatanaka M, Petrova GP, Harris TV, Li X, Ke Z, Liu F, Li HB, Ding L, Morokuma K. The ONIOM Method and Its Applications. Chem Rev 2015; 115:5678-796. [PMID: 25853797 DOI: 10.1021/cr5004419] [Citation(s) in RCA: 729] [Impact Index Per Article: 81.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Lung Wa Chung
- †Department of Chemistry, South University of Science and Technology of China, Shenzhen 518055, China
| | - W M C Sameera
- ‡Fukui Institute for Fundamental Chemistry, Kyoto University, 34-4 Takano Nishihiraki-cho, Sakyo, Kyoto 606-8103, Japan
| | - Romain Ramozzi
- ‡Fukui Institute for Fundamental Chemistry, Kyoto University, 34-4 Takano Nishihiraki-cho, Sakyo, Kyoto 606-8103, Japan
| | - Alister J Page
- §Newcastle Institute for Energy and Resources, The University of Newcastle, Callaghan 2308, Australia
| | - Miho Hatanaka
- ‡Fukui Institute for Fundamental Chemistry, Kyoto University, 34-4 Takano Nishihiraki-cho, Sakyo, Kyoto 606-8103, Japan
| | - Galina P Petrova
- ∥Faculty of Chemistry and Pharmacy, University of Sofia, Bulgaria Boulevard James Bourchier 1, 1164 Sofia, Bulgaria
| | - Travis V Harris
- ‡Fukui Institute for Fundamental Chemistry, Kyoto University, 34-4 Takano Nishihiraki-cho, Sakyo, Kyoto 606-8103, Japan.,⊥Department of Chemistry, State University of New York at Oswego, Oswego, New York 13126, United States
| | - Xin Li
- #State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Zhuofeng Ke
- ∇School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275, China
| | - Fengyi Liu
- ○Key Laboratory of Macromolecular Science of Shaanxi Province, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an, Shaanxi 710119, China
| | - Hai-Bei Li
- ■School of Ocean, Shandong University, Weihai 264209, China
| | - Lina Ding
- ▲School of Pharmaceutical Sciences, Zhengzhou University, 100 Kexue Avenue, Zhengzhou, Henan 450001, China
| | - Keiji Morokuma
- ‡Fukui Institute for Fundamental Chemistry, Kyoto University, 34-4 Takano Nishihiraki-cho, Sakyo, Kyoto 606-8103, Japan
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20
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Yuan B, Yu Z, Bernstein ER. Initial mechanisms for the decomposition of electronically excited energetic materials: 1,5′-BT, 5,5′-BT, and AzTT. J Chem Phys 2015; 142:124315. [DOI: 10.1063/1.4916111] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Bing Yuan
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872, USA
| | - Zijun Yu
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872, USA
| | - Elliot R. Bernstein
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872, USA
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21
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Yuan B, Yu Z, Bernstein ER. Initial Mechanisms for the Decomposition of Electronically Excited Energetic Salts: TKX-50 and MAD-X1. J Phys Chem A 2015; 119:2965-81. [DOI: 10.1021/jp510995z] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Bing Yuan
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872, United States
| | - Zijun Yu
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872, United States
| | - Elliot R. Bernstein
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872, United States
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22
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Xiong Y, Liu J, Zhong F, Xu T, Cheng K. Identification of the free radical produced in the photolysis of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB). J Phys Chem A 2014; 118:6858-63. [PMID: 25081131 DOI: 10.1021/jp5029867] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
1,3,5-Triamino-2,4,6-trinitrobenzene (TATB) is a typical insensitive high explosive (IHE) that possesses excellent heat, impact, and shock stability. However, it is sensitive to light irradiation, which can produce a long-lived free radical. In this study, (time-dependent) density functional theory is employed to study the features of the ground state (S0), the first singlet excited state (S1), and the first triplet excited state (T1). Results indicate the progress of photolysis, which involves an intersystem crossing from S1 to T1 followed by NO2-ONO isomerization. The long-lived radical produced in TATB photolysis is identified as the phenoxyl radical R-NO by investigating the formation feasibility and the stability. The experimental observation of the changes in the ultraviolet absorption spectra of TATB supports the identification.
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Affiliation(s)
- Ying Xiong
- Institute of Chemical Materials, CAEP , Mianyang 621900, China
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23
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Booth RS, Brynteson MD, Lee SH, Lin JJ, Butler LJ. Further studies into the photodissociation pathways of 2-bromo-2-nitropropane and the dissociation channels of the 2-nitro-2-propyl radical intermediate. J Phys Chem A 2014; 118:4707-22. [PMID: 24947044 DOI: 10.1021/jp502277v] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
These experiments investigate the decomposition mechanisms of geminal dinitro energetic materials by photolytically generating two key intermediates: 2-nitropropene and 2-nitro-2-propyl radicals. To characterize the unimolecular dissociation of each intermediate, we form them under collision-free conditions using the photodissociation of 2-bromo-2-nitropropane; the intermediates are formed at high internal energies and undergo a multitude of subsequent unimolecular dissociation events investigated herein. Complementing our prior work on this system, the new data obtained with a crossed-laser molecular beam scattering apparatus with VUV photoionization detection at Taiwan's National Synchrotron Radiation Research Center (NSRRC) and new velocity map imaging data better characterize two of the four primary 193 nm photodissociation channels. The C-Br photofission channel forming the 2-nitro-2-propyl radicals has a trimodal recoil kinetic energy distribution, P(ET), suggesting that the 2-nitro-2-propyl radicals are formed both in the ground electronic state and in two low-lying excited electronic states. The new data also revise the HBr photoelimination P(ET) forming the 2-nitropropene intermediate. We then resolved the multiple competing unimolecular dissociation channels of each photoproduct, confirming many of the channels detected in the prior study, but not all. The new data detected HONO product at m/e = 47 using 11.3 eV photoionization from both intermediates; analysis of the momentum-matched products allows us to establish that both 2-nitro-2-propyl → HONO + CH3CCH2 and 2-nitropropene → HONO + C3H4 occur. Photoionization at 9.5 eV allowed us to detect the mass 71 coproduct formed in OH loss from 2-nitro-2-propyl; a channel missed in our prior study. The dynamics of the highly exothermic 2-nitro-2-propyl → NO + acetone dissociation is also better characterized; it evidences a sideways scattered angular distribution. The detection of some stable 2-nitropropene photoproducts allows us to fit signal previously assigned to H loss from 2-nitro-2-propyl radicals. Overall, the data provide a comprehensive study of the unimolecular dissociation channels of these important nitro-containing intermediates.
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Affiliation(s)
- Ryan S Booth
- Department of Chemistry and the James Franck Institute, The University of Chicago , Chicago, Illinois 60637, United States
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24
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Yuan B, Yu Z, Bernstein ER. Initial decomposition mechanism for the energy release from electronically excited energetic materials: FOX-7 (1,1-diamino-2,2-dinitroethene, C2H4N4O4). J Chem Phys 2014; 140:074708. [DOI: 10.1063/1.4865266] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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25
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Borges I. Electronic and ionization spectra of 1,1-diamino-2,2-dinitroethylene, FOX-7. J Mol Model 2014; 20:2095. [PMID: 24535107 DOI: 10.1007/s00894-014-2095-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Accepted: 11/23/2013] [Indexed: 11/24/2022]
Abstract
Singlet, triplet and ionized states of the energetic molecule 1,1-diamino-2,2-dinitroethylene, known as FOX-7 or DADNE, were investigated using the symmetry-adapted-cluster configuration interaction (SAC-CI) ab initio wave function. The 20 computed singlet transitions, with 2 exceptions, were bright. The most intense singlet transitions were of the n₀→π type-typical of molecules having nitro groups. Fast intersystem crossing (ISC) from the 1¹A, 2¹A and 8¹A bright singlet transitions is possible. Other feasible ISC processes are discussed. The computed singlet and ionization spectra have similar features when compared to nitramide and N,N-dimethylnitramine molecules, which have only a nitro group. The ionization energies of the first 20 states have differences in comparison with Koopmans' energy values that can reach 3 eV. Moreover, the character of the first ionized states, dominated by single ionizations, is not the same when compared with the character resulting from application of Koopmans' theorem.
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Affiliation(s)
- Itamar Borges
- Departamento de Química, Instituto Militar de Engenharia, Praça General Tibúrcio, 80, 22290-270, Rio de Janeiro, Brazil,
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26
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Yuan B, Yu Z, Bernstein ER. Azole energetic materials: Initial mechanisms for the energy release from electronical excited nitropyrazoles. J Chem Phys 2014; 140:034320. [DOI: 10.1063/1.4861670] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
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27
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Chu G, Shui M, Xiong Y, Yi J, Cheng K, Xu T, Xin J, Gu Y. Investigation of ultrafast excited state dynamics of 2,2′,4,4′,6,6′-hexanitrostilbene using femtosecond transient absorption spectroscopy. RSC Adv 2014. [DOI: 10.1039/c4ra08305a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A study on the dynamics and structures of the excited states of 2,2′,4,4′,6,6′-hexanitrostilbene shows equilibrium between vibrationally hot S1 (S*1) and S1 states with lifetimes of 0.8 and 6 ps, respectively.
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Affiliation(s)
- Genbai Chu
- Science and Technology on Plasma Physics Laboratory
- Research Center of Laser Fusion
- China Academy of Engineering Physics (CAEP)
- Mianyang 621900, PR China
| | - Min Shui
- Science and Technology on Plasma Physics Laboratory
- Research Center of Laser Fusion
- China Academy of Engineering Physics (CAEP)
- Mianyang 621900, PR China
| | - Ying Xiong
- Institute of Chemical Material
- CAEP
- Mianyang 621900, PR China
| | - Jing Yi
- Institute of Chemical Material
- CAEP
- Mianyang 621900, PR China
| | - Kemei Cheng
- Institute of Chemical Material
- CAEP
- Mianyang 621900, PR China
| | - Tao Xu
- Institute of Chemical Material
- CAEP
- Mianyang 621900, PR China
| | - Jianting Xin
- Science and Technology on Plasma Physics Laboratory
- Research Center of Laser Fusion
- China Academy of Engineering Physics (CAEP)
- Mianyang 621900, PR China
| | - Yuqiu Gu
- Science and Technology on Plasma Physics Laboratory
- Research Center of Laser Fusion
- China Academy of Engineering Physics (CAEP)
- Mianyang 621900, PR China
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28
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Zhuang X, Wang J, Lan Z. Photoinduced Nonadiabatic Decay and Dissociation Dynamics of Dimethylnitramine. J Phys Chem A 2013; 117:4785-93. [DOI: 10.1021/jp402180p] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Xuhui Zhuang
- Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy
of Sciences, 189 Songling Road, Qingdao, 266101 Shandong, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Jun Wang
- Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy
of Sciences, 189 Songling Road, Qingdao, 266101 Shandong, P. R. China
| | - Zhenggang Lan
- Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy
of Sciences, 189 Songling Road, Qingdao, 266101 Shandong, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
- Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy
of Sciences, Qingdao, 266101 Shandong, P. R. China
- Qingdao Key Laboratory of Solar
Energy Utilization and Energy Storage Technology, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese
Academy of Sciences, Qingdao, 266101, Shandong, P. R. China
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29
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Molt RW, Watson T, Bazanté AP, Bartlett RJ. The great diversity of HMX conformers: probing the potential energy surface using CCSD(T). J Phys Chem A 2013; 117:3467-74. [PMID: 23477630 DOI: 10.1021/jp311073m] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The octahydro-1,3,5,7-tetranitro-1,3,5,7-tetraazocine (HMX) molecule is a very commonly studied system, in all 3 phases, because of its importance as an explosive; however, no one has ever attempted a systematic study of what all the major gas-phase conformers are. This is critical to a mechanistic study of the kinetics involved, as well as the viability of various crystalline polymorphs based on the gas-phase conformers. We have used existing knowledge of basic cyclooctane chemistry to survey all possible HMX conformers based on its fundamental ring structure. After studying what geometries are possible after second-order many-body perturbation theory (MBPT(2)) geometry optimization, we calculated the energetics using coupled cluster singles, doubles, and perturbative triples (CCSD(T))/cc-pVTZ. These highly accurate energies allow us to better calculate starting points for future mechanistic studies. Additionally, the plethora of structures are compared to existing experimental data of crystals. It is found that the crystal field effect is sometimes large and sometimes small for HMX.
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Affiliation(s)
- Robert W Molt
- Quantum Theory Project, Gainesville, Florida 32611, USA
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30
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Booth RS, Lam CS, Brynteson MD, Wang L, Butler LJ. Elucidating the Decomposition Mechanism of Energetic Materials with Geminal Dinitro Groups Using 2-Bromo-2-nitropropane Photodissociation. J Phys Chem A 2013; 117:9531-47. [DOI: 10.1021/jp312248v] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ryan S. Booth
- The James Franck Institute and Department of Chemistry, The University of Chicago, Chicago, Illinois 60637,
United States
| | - Chow-Shing Lam
- The James Franck Institute and Department of Chemistry, The University of Chicago, Chicago, Illinois 60637,
United States
| | - Matthew D. Brynteson
- The James Franck Institute and Department of Chemistry, The University of Chicago, Chicago, Illinois 60637,
United States
| | - Lei Wang
- The James Franck Institute and Department of Chemistry, The University of Chicago, Chicago, Illinois 60637,
United States
| | - Laurie J. Butler
- The James Franck Institute and Department of Chemistry, The University of Chicago, Chicago, Illinois 60637,
United States
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31
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Yu Z, Bernstein ER. On the Decomposition Mechanisms of New Imidazole-Based Energetic Materials. J Phys Chem A 2013; 117:1756-64. [DOI: 10.1021/jp312527u] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Zijun Yu
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872, United
States
| | - Elliot R. Bernstein
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872, United
States
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32
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Yu Z, Bernstein ER. Experimental and theoretical studies of the decomposition of new imidazole based energetic materials: model systems. J Chem Phys 2013; 137:114303. [PMID: 22998258 DOI: 10.1063/1.4752654] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Decomposition of three imidazole based model energetic systems (2-nitroimidazole, 4-nitroimidazole, and 1-methyl-5-nitroimidazole) is investigated both experimentally and theoretically. The initial decomposition mechanism for these three nitroimidazoles is explored with nanosecond energy resolved spectroscopy, and quantum chemical theory at the complete active space self-consistent field (CASSCF) level. The NO molecule is observed as an initial decomposition product from these three nitroimidazoles subsequent to UV excitation. A unique, excitation wavelength independent dissociation channel is observed for these three nitroimidazoles that generates the NO product with a rotationally cold (∼50 K) and a vibrationally mildly hot (∼800 K) distribution. Potential energy surface calculations at the CASSCF∕6-31G(d) level of theory illustrate that conical intersections play an important and essential role in the decomposition mechanism. Electronically excited S(2) nitroimidazole molecules relax to the S(1) state through the (S(2)∕S(1))(CI) conical intersection, and undergo a nitro-nitrite isomerization to generate the NO product from the S(1) potential energy surface. Nevertheless, NO(2) elimination and nitro-nitrite isomerization are expected to be competitive reaction mechanisms for the decomposition of these molecules on the ground state potential energy surface from the Franck-Condon equilibrium geometry through thermal dissociation.
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Affiliation(s)
- Zijun Yu
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, USA
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33
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Yu Z, Bernstein ER. Decomposition of pentaerythritol tetranitrate [C(CH2ONO2)4] following electronic excitation. J Chem Phys 2011; 135:154305. [DOI: 10.1063/1.3652893] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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34
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Zhang C, Li Y, Xiong Y, Wang X, Zhou M. Acid and Alkali Effects on the Decomposition of HMX Molecule: A Computational Study. J Phys Chem A 2011; 115:11971-8. [DOI: 10.1021/jp204698b] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Chaoyang Zhang
- Department of Chemistry, Fudan University, Shanghai 200433, China
- Institute of Chemical Materials, China Academy of Engineering Physics (CAEP), P.O. Box 919-327, Mianyang, Sichuan 621900, China
| | - Yuzhen Li
- Department of Chemistry, Fudan University, Shanghai 200433, China
| | - Ying Xiong
- Institute of Chemical Materials, China Academy of Engineering Physics (CAEP), P.O. Box 919-327, Mianyang, Sichuan 621900, China
| | - Xiaolin Wang
- China Academy of Engineering Physics (CAEP), P.O. Box 919-1, Mianyang, Sichuan 621900, China
| | - Mingfei Zhou
- Department of Chemistry, Fudan University, Shanghai 200433, China
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35
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Bhattacharya A, Bernstein ER. Nonadiabatic Decomposition of Gas-Phase RDX through Conical Intersections: An ONIOM-CASSCF Study. J Phys Chem A 2011; 115:4135-47. [DOI: 10.1021/jp109152p] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- A. Bhattacharya
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80521, United States
| | - E. R. Bernstein
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80521, United States
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36
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Asher SA, Tuschel DD, Vargson TA, Wang L, Geib SJ. Solid State and Solution Nitrate Photochemistry: Photochemical Evolution of the Solid State Lattice. J Phys Chem A 2011; 115:4279-87. [DOI: 10.1021/jp200406q] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Sanford A. Asher
- Department of Chemistry, University of Pittsburgh, Pittsburgh Pennsylvania 15260, United States
| | - David D. Tuschel
- Department of Chemistry, University of Pittsburgh, Pittsburgh Pennsylvania 15260, United States
| | - Todd A. Vargson
- Department of Chemistry, University of Pittsburgh, Pittsburgh Pennsylvania 15260, United States
| | - Luling Wang
- Department of Chemistry, University of Pittsburgh, Pittsburgh Pennsylvania 15260, United States
| | - Steven J. Geib
- Department of Chemistry, University of Pittsburgh, Pittsburgh Pennsylvania 15260, United States
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37
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Initial reactions of methyl-nitramine confined inside armchair (5,5) single-walled carbon nanotube. J Mol Model 2011; 17:2751-8. [DOI: 10.1007/s00894-011-0967-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2010] [Accepted: 01/10/2011] [Indexed: 10/18/2022]
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38
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Guo Y, Bhattacharya A, Bernstein ER. Decomposition of excited electronic state s-tetrazine and its energetic derivatives. J Chem Phys 2011; 134:024318. [DOI: 10.1063/1.3523649] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
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39
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Molt RW, Watson T, Lotrich VF, Bartlett RJ. RDX Geometries, Excited States, and Revised Energy Ordering of Conformers via MP2 and CCSD(T) Methodologies: Insights into Decomposition Mechanism. J Phys Chem A 2011; 115:884-90. [PMID: 21210658 DOI: 10.1021/jp109695v] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Robert W Molt
- Quantum Theory Project, Gainesville, Florida 32611, USA.
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40
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Bhattacharya A, Guo Y, Bernstein ER. Nonadiabatic reaction of energetic molecules. Acc Chem Res 2010; 43:1476-85. [PMID: 20931955 DOI: 10.1021/ar100067f] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Energetic materials store a large amount of chemical energy that can be readily converted into mechanical energy via decomposition. A number of different ignition processes such as sparks, shocks, heat, or arcs can initiate the excited electronic state decomposition of energetic materials. Experiments have demonstrated the essential role of excited electronic state decomposition in the energy conversion process. A full understanding of the mechanisms for the decomposition of energetic materials from excited electronic states will require the investigation and analysis of the specific topography of the excited electronic potential energy surfaces (PESs) of these molecules. The crossing of multidimensional electronic PESs creates a funnel-like topography, known as conical intersections (CIs). CIs are well established as a controlling factor in the excited electronic state decomposition of polyatomic molecules. This Account summarizes our current understanding of the nonadiabatic unimolecular chemistry of energetic materials through CIs and presents the essential role of CIs in the determination of decomposition pathways of these energetic systems. Because of the involvement of more than one PES, a decomposition process involving CIs is an electronically nonadiabatic mechanism. Based on our experimental observations and theoretical calculations, we find that a nonadiabatic reaction through CIs dominates the initial decomposition process of energetic materials from excited electronic states. Although the nonadiabatic behavior of some polyatomic molecules has been well studied, the role of nonadiabatic reactions in the excited electronic state decomposition of energetic molecules has not been well investigated. We use both nanosecond energy-resolved and femtosecond time-resolved spectroscopic techniques to determine the decomposition mechanism and dynamics of energetic species experimentally. Subsequently, we employ multiconfigurational methodologies (such as, CASSCF, CASMP2) to model nonadiabatic molecular processes of energetic molecules computationally. Synergism between experiment and theory establishes a coherent description of the nonadiabatic reactivity of energetic materials at a molecular level. Energetic systems discussed in this Account are nitramine- and furazan-based species. Both energetic species and their respective model systems, which are not energetic, are studied and discussed in detail. The model systems have similar molecular structures to those of the energetic species and help significantly in understanding the decomposition behavior of the larger and more complex energetic molecules. Our results for the above systems of interest confirm the existence of CIs and energy barriers on the PESs of interest. The presence of the CIs and barriers along the various reaction coordinates control the nonadiabatic behavior of the decomposition process. The detailed nature of the PESs and their CIs consequently differentiate the energetic systems from model systems. Energy barriers to the chemically relevant low-lying CIs of a molecule determine whether that molecule is more or less "energetic".
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Affiliation(s)
- Atanu Bhattacharya
- Department of Chemistry, Colorado State University, Fort Collins, Colorado
| | - Yuanqing Guo
- Department of Chemistry, Colorado State University, Fort Collins, Colorado
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41
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Roberson SD, Sausa RC. Laser-based detection of TNT and RDX residues in real time under ambient conditions. APPLIED SPECTROSCOPY 2010; 64:760-766. [PMID: 20615289 DOI: 10.1366/000370210791666327] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We detect thin films of 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5-hexanitro-1,3,5-triazine (RDX) by one- and two-laser photofragmentation-fragment detection spectroscopy in real time at ambient temperature and pressure. In the one-laser technique, a laser tuned to 226 nm excites the energetic material and both generates the characteristic NO photofragments and facilitates their detection by resonance-enhanced multiphoton ionization (REMPI) using their A-X (0,0) transitions near 226 nm. In contrast, in the two-laser technique, a 454 nm laser generates the analyte molecule in the gas phase by matrix-assisted desorption, and a second laser tuned to 226 nm both photofragments it and ionizes the resulting NO. We report the effects of laser energy, analyte concentration, and matrix concentration on the ion signal and determine the rotational temperatures of the NO photofragments from Boltzmann, rotational distribution analysis of the REMPI spectra. We achieve limits of detection (S/N = 3) of hundreds of ng/cm(2) for both techniques under ambient conditions with a positive signal identification as low as 70 pg using a single 226 nm laser pulse of approximately 50 microJ.
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Affiliation(s)
- Stephen D Roberson
- US Army Research Laboratory, RDRL-WML-B, Aberdeen Proving Ground, Maryland 21005-5069, USA
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42
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Wynn CM, Palmacci S, Kunz RR, Rothschild M. Noncontact detection of homemade explosive constituents via photodissociation followed by laser-induced fluorescence. OPTICS EXPRESS 2010; 18:5399-5406. [PMID: 20389555 DOI: 10.1364/oe.18.005399] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Noncontact detection of the homemade explosive constituents urea nitrate, nitromethane and ammonium nitrate is achieved using photodissociation followed by laser-induced fluorescence (PD-LIF). Our technique utilizes a single ultraviolet laser pulse (approximately 7 ns) to vaporize and photodissociate the condensed-phase materials, and then to detect the resulting vibrationally-excited NO fragments via laser-induced fluorescence. PD-LIF excitation and emission spectra indicate the creation of NO in vibrationally-excited states with significant rotational energy, useful for low-background detection of the parent compound. The results for homemade explosives are compared to one another and 2,6-dinitrotoluene, a component present in many military explosives.
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Affiliation(s)
- C M Wynn
- Lincoln Laboratory, Massachusetts Institute of Technology, 244 Wood Street, Lexington, MA 02420, USA.
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43
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Ghule VD, Jadhav PM, Patil RS, Radhakrishnan S, Soman T. Quantum-chemical studies on hexaazaisowurtzitanes. J Phys Chem A 2010; 114:498-503. [PMID: 20000482 DOI: 10.1021/jp9071839] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Highly nitrated cage molecules constitute a new class of energetic materials that have received a substantial amount of interest. Among them 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) is a powerful explosive with poor impact and friction characteristics. In the present study we aim to design novel energetic materials by tailoring the molecular structure of CL-20. Important characteristics such as the heat of formation and density have been predicted using density functional theory and packing calculations, respectively. Sensitivity correlations have been established for model compounds by analyzing the charge on the nitro groups. Molecules IDX1, IDX4, and IDX7 have been found to have comparable performance with better insensitivity characteristics and may be explored as CL-20 substitutes in defense applications.
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Affiliation(s)
- V D Ghule
- ACRHEM, University of Hyderabad, Hyderabad, Pune, India
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44
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Bhattacharya A, Guo YQ, Bernstein ER. Experimental and Theoretical Exploration of the Initial Steps in the Decomposition of a Model Nitramine Energetic Material: Dimethylnitramine. J Phys Chem A 2009; 113:811-23. [DOI: 10.1021/jp807247t] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- A. Bhattacharya
- Department of Chemistry, Colorado State University, Fort Collins, Colorado
| | - Y. Q. Guo
- Department of Chemistry, Colorado State University, Fort Collins, Colorado
| | - E. R. Bernstein
- Department of Chemistry, Colorado State University, Fort Collins, Colorado
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45
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Bhattacharya A, Guo YQ, Bernstein ER. Unimolecular decomposition of tetrazine-N-oxide based high nitrogen content energetic materials from excited electronic states. J Chem Phys 2009; 131:194304. [DOI: 10.1063/1.3262688] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Guo YQ, Bhattacharya A, Bernstein ER. Photodissociation Dynamics of Nitromethane at 226 and 271 nm at Both Nanosecond and Femtosecond Time Scales. J Phys Chem A 2008; 113:85-96. [DOI: 10.1021/jp806230p] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Y. Q. Guo
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872
| | - A. Bhattacharya
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872
| | - E. R. Bernstein
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872
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Guo YQ, Bhattacharya A, Bernstein ER. Excited electronic state decomposition of furazan based energetic materials: 3,3′-diamino-4,4′-azoxyfurazan and its model systems, diaminofurazan and furazan. J Chem Phys 2008; 128:034303. [DOI: 10.1063/1.2822283] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
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