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Hutches KD, Wang D, Land DP. The effect of laser power density on the observed products of combustion of gasoline using laser-induced thermal desorption with Fourier transform mass spectrometry. J Forensic Sci 2012; 58 Suppl 1:S192-8. [PMID: 23216203 DOI: 10.1111/1556-4029.12021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2010] [Revised: 11/02/2011] [Accepted: 01/17/2012] [Indexed: 11/26/2022]
Abstract
Layered soot analysis is explored as a potential indicator of gasoline in a fire. Current techniques lack the ability to analyze layered soot samples without the destruction of the layered information. Laser-induced thermal desorption (LITD) coupled with Fourier transform mass spectrometry (FTMS) is developed as a method for analyzing soot samples. Samples of soot on glass from the free combustion of gasoline are collected and analyzed using LITD-FTMS, and the effect of power density on the resulting chemical profile is reported. At higher power densities, a distribution of low m/z products is observed. At lower power densities, the products observed shift to higher molecular weights, with peaks attributable to the tropyllium ion, naphthalene, and pyrene. Results at low power densities suggest that LITD-FTMS is a viable method for the analysis of soot, with potential for use with layered soot samples. Peaks potentially useful for fuel differentiation of gasoline are identified.
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Affiliation(s)
- Katherine D Hutches
- Department of Chemistry, University of California, One Shields Avenue, Davis, CA 95616, USA
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Matsugi A, Miyoshi A. Reactions of o-benzyne with propargyl and benzyl radicals: potential sources of polycyclic aromatic hydrocarbons in combustion. Phys Chem Chem Phys 2012; 14:9722-8. [PMID: 22678346 DOI: 10.1039/c2cp41002h] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The kinetics and mechanisms of the reactions of o-benzyne with propargyl and benzyl radicals have been investigated computationally. The possible reaction pathways have been explored by quantum chemical calculations at the M06-2X/6-311+G(3df,2p)//B3LYP/6-311G(d,p) level and the mechanisms have been investigated by the Rice-Ramsperger-Kassel-Marcus theory/master-equation calculations. It was found that the o-benzyne associates with the propargyl and benzyl radicals without pronounced barriers and the activated adducts easily isomerize to five-membered ring species. Indenyl radical and fluorene + H were predicted to be dominantly produced by the reactions of o-benzyne with propargyl and benzyl radicals, respectively, with the rate constants close to the high-pressure limits at temperatures below 2000 K. The related reactions on the two potential energy surfaces, namely, the reaction between fulvenallenyl radical and acetylene and the decomposition reactions of indenyl and α-phenylbenzyl radicals were also investigated. The high reactivity of o-benzyne toward the resonance stabilized radicals suggested a potential role of o-benzyne as a precursor of polycyclic aromatic hydrocarbons in combustion.
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Affiliation(s)
- Akira Matsugi
- Department of Chemical System Engineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
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Koley D, Arunan E, Ramakrishnan S. Computational investigations on covalent dimerization/oligomerization of polyacenes: is it relevant to soot formation? J Comput Chem 2012; 33:1762-72. [PMID: 22610914 DOI: 10.1002/jcc.23014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Revised: 04/23/2012] [Accepted: 04/24/2012] [Indexed: 01/17/2023]
Abstract
We have postulated a novel pathway that could assist in the nucleation of soot particles through covalent dimerization and oligomerizations of a variety of PAHs. DFT calculations were performed with the objective of obtaining the relative thermal stabilities and formation probabilities of oligomeric species that exploit the facile dimerization that is known to occur in linear oligoacenes. We propose that the presence of small stretches of linear oligoacence (tetracene or longer) in extended PAH, either embedded or tethered, would be adequate for enabling the formation of such dimeric and oligomeric adducts; these could then serve as nuclei for the growth of soot particles. Our studies also reveal the importance of π-stacking interactions between extended aromatic frameworks in governing the relative stabilities of the oligomeric species that are formed.
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Affiliation(s)
- D Koley
- Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore, Karnataka, India.
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Zhang F, Kaiser RI, Golan A, Ahmed M, Hansen N. A VUV Photoionization Study of the Combustion-Relevant Reaction of the Phenyl Radical (C6H5) with Propylene (C3H6) in a High Temperature Chemical Reactor. J Phys Chem A 2012; 116:3541-6. [DOI: 10.1021/jp300875s] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Fangtong Zhang
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii 96822,
United States
| | - Ralf I. Kaiser
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii 96822,
United States
| | - Amir Golan
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United
States
| | - Musahid Ahmed
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United
States
| | - Nils Hansen
- Combustion
Research Facility, Sandia National Laboratories, Livermore, California 94551, United States
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Tanaka K, Ando M, Sakamoto Y, Tonokura K. Pressure dependence of phenylperoxy radical formation in the reaction of phenyl radical with molecular oxygen. INT J CHEM KINET 2011. [DOI: 10.1002/kin.20615] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Shukla B, Tsuchiya K, Koshi M. Novel Products from C6H5 + C6H6/C6H5 Reactions. J Phys Chem A 2011; 115:5284-93. [DOI: 10.1021/jp201817n] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Bikau Shukla
- Department of Aerospace and Mechanical Engineering, The University of Southern California, Los Angeles, California, United States
| | - Kentaro Tsuchiya
- Energy Technology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
| | - Mitsuo Koshi
- Institute of Engineering Innovation, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
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Tranter RS, Klippenstein SJ, Harding LB, Giri BR, Yang X, Kiefer JH. Experimental and theoretical investigation of the self-reaction of phenyl radicals. J Phys Chem A 2010; 114:8240-61. [PMID: 20701334 DOI: 10.1021/jp1031064] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A combination of experiment and theory is applied to the self-reaction kinetics of phenyl radicals. The dissociation of phenyl iodide is observed with both time-of-flight mass spectrometry, TOF-MS, and laser schlieren, LS, diagnostics coupled to a diaphragmless shock tube for temperatures ranging from 1276 to 1853 K. The LS experiments were performed at pressures of 22 +/- 2, 54 +/- 7, and 122 +/- 6 Torr, and the TOF-MS experiments were performed at pressures in the range 500-700 Torr. These observations are sensitive to both the dissociation of phenyl iodide and to the subsequent self-reaction of the phenyl radicals. The experimental observations indicate that both these reactions are more complicated than previously assumed. The phenyl iodide dissociation yields approximately 6% C(6)H(4) + HI in addition to the major and commonly assumed C(6)H(5) + I channel. The self-reaction of phenyl radicals does not proceed solely by recombination, but also through disproportionation to benzene + o-/m-/p-benzynes, with comparable rate coefficients for both. The various channels in the self-reaction of phenyl radicals are studied with ab initio transition state theory based master equation calculations. These calculations elucidate the complex nature of the C(6)H(5) self-reaction and are consistent with the experimental observations. The theoretical predictions are used as a guide in the development of a model for the phenyl iodide pyrolysis that accurately reproduces the observed laser schlieren profiles over the full range of the observations.
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Affiliation(s)
- Robert S Tranter
- Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, USA.
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Negru B, Goncher SJ, Brunsvold AL, Just GMP, Park D, Neumark DM. Photodissociation dynamics of the phenyl radical via photofragment translational spectroscopy. J Chem Phys 2010; 133:074302. [DOI: 10.1063/1.3473743] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Shukla B, Miyoshi A, Koshi M. Role of methyl radicals in the growth of PAHs. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2010; 21:534-544. [PMID: 20149680 DOI: 10.1016/j.jasms.2009.12.019] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2009] [Revised: 12/23/2009] [Accepted: 12/23/2009] [Indexed: 05/28/2023]
Abstract
The role of methyl radicals in the networking of sp(2) carbons has been explored through kinetic analysis of mass spectra of the gas-phase products of the pyrolysis of toluene and toluene/acetone mixtures. Pyrolytic reactions were performed in a flow tube reactor at temperatures of 1140-1320 K and a constant total pressure of 10.38 Torr with a residence time of 0.585 s. On addition of acetone, methyl substituted products and their derivatives were enhanced. Mass peaks were observed in several sequences at an interval of 14 mass units; these ions correspond to methyl substituted products formed as a result of hydrogen abstraction (-H) followed by methyl radical addition (+CH(3)). Each major peak was usually preceded by a peak at two mass units lower, which was likely produced through dehydrogenation/dehydrocyclization (-H(2)) of methyl substituted products. Detected species include a large number of alkyl, cyclotetrafused (CT), cyclopentafused (CP) mono-, di-, and polycyclic aromatic hydrocarbons (PAHs) along with primary PAHs. The analysis showed that MAC (methyl addition/cyclization) has a unique capacity to induce the sequential growth of hexagonal networks of sp(2) carbons from all fusing sites of a PAH. Moreover, MAC was found capable of answering an important question in PAH growth, which is expansion of the CT --> CP --> hexagonal network for which other reported mechanisms are inefficient.
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Affiliation(s)
- Bikau Shukla
- National Institute of Advanced Industrial Science and Technology, Higashi, Tsukuba, Japan
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Zhang F, Jones B, Maksyutenko P, Kaiser RI, Chin C, Kislov VV, Mebel AM. Formation of the Phenyl Radical [C6H5(X2A1)] under Single Collision Conditions: A Crossed Molecular Beam and ab Initio Study. J Am Chem Soc 2010; 132:2672-83. [DOI: 10.1021/ja908559v] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Fangtong Zhang
- Department of Chemistry, University of Hawai’i, Honolulu, Hawaii 96822, and Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199
| | - Brant Jones
- Department of Chemistry, University of Hawai’i, Honolulu, Hawaii 96822, and Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199
| | - Pavlo Maksyutenko
- Department of Chemistry, University of Hawai’i, Honolulu, Hawaii 96822, and Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199
| | - Ralf I. Kaiser
- Department of Chemistry, University of Hawai’i, Honolulu, Hawaii 96822, and Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199
| | - Christine Chin
- Department of Chemistry, University of Hawai’i, Honolulu, Hawaii 96822, and Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199
| | - Vadim V. Kislov
- Department of Chemistry, University of Hawai’i, Honolulu, Hawaii 96822, and Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199
| | - Alexander M. Mebel
- Department of Chemistry, University of Hawai’i, Honolulu, Hawaii 96822, and Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199
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Shukla B, Koshi M. A highly efficient growth mechanism of polycyclic aromatic hydrocarbons. Phys Chem Chem Phys 2010; 12:2427-37. [DOI: 10.1039/b919644g] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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