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Sun YL, Huang WJ, Lee SH. Formations of C6H from reactions C3 + C3H2 and C3H + C3H and of C8H from reactions C4 + C4H2 and C4H + C4H. J Chem Phys 2024; 160:044303. [PMID: 38258925 DOI: 10.1063/5.0184683] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Accepted: 01/01/2024] [Indexed: 01/24/2024] Open
Abstract
We interrogated C6H and C8H produced separately from the reactions C3 + C3H2/C3H + C3H/C3H2 + C3 → C6H + H and C4 + C4H2/C4H + C4H/C4H2 + C4 → C8H + H using product translational and photoionization spectroscopy. Individual contributions of the three reactions to the product C6H or C8H were evaluated with reactant concentrations. Translational-energy distributions, angular distributions, and photoionization efficiency curves of products C6H and C8H were unraveled. The product C6H (C8H) was recognized as the most stable linear isomer by comparing its photoionization efficiency curve with that of l-C6H (l-C8H), produced exclusively from the reaction C2 + C4H2 → l-C6H + H (C2 + C6H2 → l-C8H + H). The ionization threshold after deconvolution was determined to be 9.3 ± 0.1 eV for l-C6H and 8.9 ± 0.1 eV for l-C8H, which is in good agreement with theoretical values. Quantum-chemical calculations indicate that the reactions of C3 + C3H2 and C3H + C3H (C4 + C4H2 and C4H + C4H) incur no energy barriers that lie above the corresponding reactant and the most stable product l-C6H (l-C8H) with H on the lower-lying potential-energy surfaces. The theoretical calculation is in accord with the experimental observation. This work implies that the reactions of C3 + C3H2/C3H + C3H and C4 + C4H2/C4H + C4H need to be taken into account for the formation of interstellar C6H and C8H, respectively.
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Affiliation(s)
- Yi-Lun Sun
- National Synchrotron Radiation Research Center (NSRRC), 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 300092, Taiwan
| | - Wen-Jian Huang
- National Synchrotron Radiation Research Center (NSRRC), 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 300092, Taiwan
| | - Shih-Huang Lee
- National Synchrotron Radiation Research Center (NSRRC), 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 300092, Taiwan
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Sun YL, Huang WJ, Lee SH. Study on Formation of Interstellar C 7H from Reactions C 4 + C 3H 2 and C 4H + C 3H. J Phys Chem A 2024; 128:456-465. [PMID: 38181389 DOI: 10.1021/acs.jpca.3c07091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2024]
Abstract
We interrogated C7H produced from reactions C4 + C3H2/C4H + C3H → C7H + H using both translational and photoionization spectroscopy. Reactants C3H, C3H2, C4, and C4H were synthesized in two crossed beams of 1% C2H2/He ignited by pulsed high-voltage discharge. The individual contributions of reactions C4 + C3H2 and C4H + C3H to product C7H were evaluated as 17:83 from reactant concentrations in both molecular beams. The translational energy distribution, the angular distribution, and the photoionization efficiency curve of product C7H were unraveled. C7H was identified as the most stable linear isomer by its photoionization efficiency curve that features two ionization thresholds corresponding to separate transitions to singlet and triplet states of l-C7H+. The quantum-chemical calculations indicate that the associations of C4 with C3H2 and C4H with C3H incur no entrance barriers, and the most favorable exit channel leads to product l-C7H + H. It is the first time demonstrating that C7H is producible from reactions 1,3C4 + 1C3H2 and 2C4H + 2C3H on the lowest-lying singlet and triplet potential energy surfaces of 1,3C7H2. This work implies that the reactions of C4 + C3H2 and C4H + C3H might have contributions to interstellar C7H to some extent as compared with the C + C6H2 reaction commonly adopted in an astrochemical model.
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Affiliation(s)
- Yi-Lun Sun
- National Synchrotron Radiation Research Center (NSRRC), 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 300092, Taiwan
| | - Wen-Jian Huang
- National Synchrotron Radiation Research Center (NSRRC), 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 300092, Taiwan
| | - Shih-Huang Lee
- National Synchrotron Radiation Research Center (NSRRC), 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 300092, Taiwan
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Thomas AM, Lucas M, Zhao L, Liddiard J, Kaiser RI, Mebel AM. A combined crossed molecular beams and computational study on the formation of distinct resonantly stabilized C 5H 3 radicals via chemically activated C 5H 4 and C 6H 6 intermediates. Phys Chem Chem Phys 2018. [PMID: 29537029 DOI: 10.1039/c8cp00357b] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The crossed molecular beams technique was utilized to explore the formation of three isomers of resonantly stabilized (C5H3) radicals along with their d2-substituted counterparts via the bimolecular reactions of singlet/triplet dicarbon [C2(X1Σ+g/a3Πu)] with methylacetylene [CH3CCH(X1A1)], d3-methylacetylene [CD3CCH(X1A1)], and 1-butyne [C2H5CCH(X1A')] at collision energies up to 26 kJ mol-1via chemically activated singlet/triplet C5H4/C5D3H and C6H6 intermediates. These studies exploit a newly developed supersonic dicarbon [C2(X1Σ+g/a3Πu)] beam generated via photolysis of tetrachloroethylene [C2Cl4(X1Ag)] by excluding interference from carbon atoms, which represent the dominating (interfering) species in ablation-based dicarbon sources. We evaluated the performance of the dicarbon [C2(X1Σ+g/a3Πu)] beam in reactions with methylacetylene [CH3CCH(X1A1)] and d3-methylacetylene [CD3CCH(X1A1)]; the investigations demonstrate that the reaction dynamics match previous studies in our laboratory utilizing ablation-based dicarbon sources involving the synthesis of 1,4-pentadiynyl-3 [HCCCHCCH(X2B1)] and 2,4-pentadiynyl-1 [H2CCCCCH(X2B1)] radicals via hydrogen (deuterium) atom elimination. Considering the C2(X1Σ+g/a3Πu)-1-butyne [C2H5CCH(X1A')] reaction, the hitherto elusive methyl-loss pathway was detected. This channel forms the previously unknown resonantly stabilized penta-1-yn-3,4-dienyl-1 [H2CCCHCC(X2A)] radical along with the methyl radical [CH3(X2A2'')] and is open exclusively on the triplet surface with an overall reaction energy of -86 ± 10 kJ mol-1. The preferred reaction pathways proceed first by barrierless addition of triplet dicarbon to the π-electronic system of 1-butyne, either to both acetylenic carbon atoms or to the sterically more accessible carbon atom, to form the methyl-bearing triplet C6H6 intermediates [i41b] and [i81b], respectively, with the latter decomposing via a tight exit transition state to penta-1-yn-3,4-dienyl-1 [(H2CCCHCC(X2A)] plus the methyl radical [CH3(X2A2'')]. The successful unraveling of this methyl-loss channel - through collaborative experimental and computational efforts - underscores the viability of the photolytically generated dicarbon beam as an unprecedented tool to access reaction dynamics underlying the formation of resonantly stabilized free radicals (RSFR) that are vital to molecular mass growth processes that ultimately lead to polycyclic aromatic hydrocarbons (PAHs).
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Affiliation(s)
- Aaron M Thomas
- Department of Chemistry, University of Hawai'i at Mānoa, Honolulu, HI 96822, USA.
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Mebel AM, Kaiser RI. Formation of resonantly stabilised free radicals via the reactions of atomic carbon, dicarbon, and tricarbon with unsaturated hydrocarbons: theory and crossed molecular beams experiments. INT REV PHYS CHEM 2015. [DOI: 10.1080/0144235x.2015.1075280] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Alexander M. Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA
| | - Ralf I. Kaiser
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, HI 96822, USA
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Sun YL, Huang WJ, Chin CH, Lee SH. Dynamics of the reaction of C2 with C6H2: an implication for the formation of interstellar C8H. J Chem Phys 2014; 141:194305. [PMID: 25416889 DOI: 10.1063/1.4901981] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The reaction C2 + C6H2 → C8H + H was investigated for the first time. Reactant C2 (C6H2) was synthesized from 1% C3F6/He (5% C2H2/He) by pulsed high-voltage discharge. We measured the translational-energy distribution, the angular distribution, and the photoionization spectrum of product C8H in a crossed molecular-beam apparatus using synchrotron vacuum-ultraviolet ionization. This reaction released average translational energy of 8.5 kcal mol(-1) corresponding to a fraction of 0.37 in translation. C8H was identified as octatetranyl based on the maximal translational-energy release 23 ± 2 kcal mol(-1) and the ionization threshold 8.9 ± 0.2 eV. Kinematic constraints can qualitatively account for the nearly isotropic angular distribution. The quantum-chemical calculations indicate that the exothermic reactions C2 (X (1)Σg (+)/a (3)Πu) + HC6H → C8H + H can proceed without entrance and exit barriers, implying the importance in the cold interstellar medium. This work verifies that interstellar C8H can be formed through the C2 + C6H2 reaction.
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Affiliation(s)
- Yi-Lun Sun
- National Synchrotron Radiation Research Center (NSRRC), 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan
| | - Wen-Jian Huang
- National Synchrotron Radiation Research Center (NSRRC), 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan
| | - Chih-Hao Chin
- National Synchrotron Radiation Research Center (NSRRC), 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan
| | - Shih-Huang Lee
- National Synchrotron Radiation Research Center (NSRRC), 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan
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Čurík R, Paidarová I, Allan M, Čársky P. Joint Experimental and Theoretical Study on Vibrational Excitation Cross Sections for Electron Collisions with Diacetylene. J Phys Chem A 2014; 118:9734-44. [DOI: 10.1021/jp5073186] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Roman Čurík
- J.
Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v.v.i., Dolejškova 3, 18223 Prague 8, Czech Republic
| | - Ivana Paidarová
- J.
Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v.v.i., Dolejškova 3, 18223 Prague 8, Czech Republic
| | - Michael Allan
- Department
of Chemistry, University of Fribourg, Chemin du Musée 9, CH-1700 Fribourg, Switzerland
| | - Petr Čársky
- J.
Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v.v.i., Dolejškova 3, 18223 Prague 8, Czech Republic
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Dangi BB, Maity S, Kaiser RI, Mebel AM. A Combined Crossed Beam and Ab Initio Investigation of the Gas Phase Reaction of Dicarbon Molecules (C2; X1Σg+/a3Πu) with Propene (C3H6; X1A′): Identification of the Resonantly Stabilized Free Radicals 1- and 3-Vinylpropargyl. J Phys Chem A 2013; 117:11783-93. [DOI: 10.1021/jp402700j] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Beni B. Dangi
- Department of Chemistry, University of Hawai’i at Manoa, Honolulu, Hawaii 96822, United
States
| | - Surajit Maity
- Department of Chemistry, University of Hawai’i at Manoa, Honolulu, Hawaii 96822, United
States
| | - Ralf I. Kaiser
- Department of Chemistry, University of Hawai’i at Manoa, Honolulu, Hawaii 96822, United
States
| | - Alexander M. Mebel
- Department of Chemistry
and Biochemistry, Florida International University, Miami, Florida 33199, United States
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Maksyutenko P, Zhang F, Kim YS, Kaiser RI, Chen SH, Wu CC, Chang AHH. Untangling the chemical dynamics of the reaction of boron atoms, 11B(2Pj), with diacetylene, C4H2(X1Σg+)--a crossed molecular beams and ab initio study. J Phys Chem A 2010; 114:10936-43. [PMID: 20873840 DOI: 10.1021/jp1065067] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A crossed molecular beams experiment with ground state boron atoms, B((2)P(j)), and diacetylene, C(4)H(2)(X(1)Σ(g)(+)), was conducted at a collision energy of 21.1 ± 0.3 kJ mol(-1) under single collision conditions and combined with electronic structure calculations on the (11)BC(4)H(2) potential energy surface. Our combined experimental and computational studies indicate that the reaction proceeds without entrance barrier and involves indirect scattering dynamics. Three initial collision complexes, in which the boron atom adds to one or two carbon atoms, were characterized computationally. These intermediates rearranged via hydrogen shifts and/or successive ring-opening/ring closure processes on the doublet surface ultimately yielding a cyclic, C(s) symmetric (11)BC(4)H(2) intermediate. The latter was found to decompose via atomic hydrogen loss to yield a cyclic (11)BC(4)H(X(1)A') isomer; to a minor amount, the cyclic intermediate isomerized via ring-opening to the linear HCCBCCH(X(2)Σ(g)(+)) molecule, which in turn emitted a hydrogen atom to yield the linear HCCBCC(X(1)Σ(+)) molecule. The overall reactions to form these isomers were found to be exoergic by 55 and 61 J mol(-1), respectively, and involved rather loose exit transition states. On the basis of the energetics, upper limits of two energetically less stable species, the linear HBCCCC(X(1)Σ(+)) and BCCCCH(X(1)Σ(+)) species, were derived to be 12 and 2.2%, respectively. The dynamics of this reaction are also compared with the reaction of ground state boron atoms with acetylene studied earlier in our group.
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Affiliation(s)
- Pavlo Maksyutenko
- Department of Chemistry, University of Hawai'i, Honolulu, Hawaii 96822, USA
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9
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Leonori F, Hickson KM, Le Picard SD, Wang X, Petrucci R, Foggi P, Balucani N, Casavecchia P. Crossed-beam universal-detection reactive scattering of radical beams characterized by laser-induced-fluorescence: the case of C2and CN. Mol Phys 2010. [DOI: 10.1080/00268971003657110] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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10
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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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11
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Kovács T, Blitz MA, Seakins PW. H-Atom Yields from the Photolysis of Acetylene and from the Reaction of C2H with H2, C2H2, and C2H4. J Phys Chem A 2010; 114:4735-41. [DOI: 10.1021/jp908285t] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Tamás Kovács
- School of Chemistry, University of Leeds, Leeds, LS2 9JT, United Kingdom
| | - Mark A. Blitz
- School of Chemistry, University of Leeds, Leeds, LS2 9JT, United Kingdom
| | - Paul W. Seakins
- School of Chemistry, University of Leeds, Leeds, LS2 9JT, United Kingdom
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12
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Berteloite C, Le Picard SD, Balucani N, Canosa A, Sims IR. Low temperature rate coefficients for reactions of the butadiynyl radical, C4H, with various hydrocarbons. Part I: reactions with alkanes (CH4, C2H6, C3H8, C4H10). Phys Chem Chem Phys 2010; 12:3666-76. [DOI: 10.1039/b907154g] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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13
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Kaiser RI, Maksyutenko P, Ennis C, Zhang F, Gu X, Krishtal SP, Mebel AM, Kostko O, Ahmed M. Untangling the chemical evolution of Titan's atmosphere and surface–from homogeneous to heterogeneous chemistry. Faraday Discuss 2010; 147:429-78; discussion 527-52. [DOI: 10.1039/c003599h] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Balucani N. Elementary reactions and their role in gas-phase prebiotic chemistry. Int J Mol Sci 2009; 10:2304-2335. [PMID: 19564951 PMCID: PMC2695279 DOI: 10.3390/ijms10052304] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2009] [Revised: 05/13/2009] [Accepted: 05/15/2009] [Indexed: 11/23/2022] Open
Abstract
The formation of complex organic molecules in a reactor filled with gaseous mixtures possibly reproducing the primitive terrestrial atmosphere and ocean demonstrated more than 50 years ago that inorganic synthesis of prebiotic molecules is possible, provided that some form of energy is provided to the system. After that groundbreaking experiment, gas-phase prebiotic molecules have been observed in a wide variety of extraterrestrial objects (including interstellar clouds, comets and planetary atmospheres) where the physical conditions vary widely. A thorough characterization of the chemical evolution of those objects relies on a multi-disciplinary approach: 1) observations allow us to identify the molecules and their number densities as they are nowadays; 2) the chemistry which lies behind their formation starting from atoms and simple molecules is accounted for by complex reaction networks; 3) for a realistic modeling of such networks, a number of experimental parameters are needed and, therefore, the relevant molecular processes should be fully characterized in laboratory experiments. A survey of the available literature reveals, however, that much information is still lacking if it is true that only a small percentage of the elementary reactions considered in the models have been characterized in laboratory experiments. New experimental approaches to characterize the relevant elementary reactions in laboratory are presented and the implications of the results are discussed.
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Affiliation(s)
- Nadia Balucani
- Dipartimento di Chimica, Università degli Studi di Perugia, 06123 Perugia, Italy; E-Mail:
; Tel. +39-075-585-5513; Fax: +39-075-585-5606
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15
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Zhang F, Kim S, Kaiser RI, Mebel AM. Formation of the 1,3,5-hexatriynyl radical (C6H(X(2)Pi)) via the crossed beams reaction of dicarbon (C2(X(1)Sigma(g)+/a(3)Pi(u))), with diacetylene (C4H2(X(1)Sigma(g)+)). J Phys Chem A 2009; 113:1210-7. [PMID: 19161290 DOI: 10.1021/jp807685v] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Crossed molecular beams experiments were conducted to investigate the chemical dynamics of the reaction of dicarbon molecules, C(2)(X(1)Sigma(g)(+)/a(3)Pi(u)), with diacetylene, C(4)H(2)(X(1)Sigma(g)(+)) at two collision energies of 12.1 and 32.8 kJ mol(-1). The dynamics were found to be indirect, involved C(6)H(2) intermediates, and were dictated by an initial addition of the dicarbon molecule to the carbon-carbon triple bond of diacetylene. The initial collision complexes could isomerize. On the singlet surface, the resulting linear triacetylene molecule (C(6)H(2)(X(1)Sigma(g)(+))) decomposed without an exit barrier to form the linear 1,3,5-hexatriynyl radical (C(6)H(X(2)Pi)). On the triplet surface, the dynamics suggested at least a tight exit transition state involved in the fragmentation of a triplet C(6)H(2) intermediate to yield the 1,3,5-hexatriynyl radical (C(6)H(X(2)Pi)) plus atomic hydrogen. On the basis of the experimental data, we recommend an experimentally determined enthalpy of formation of the 1,3,5-hexatriynyl radical of 1014 +/- 27 kJ mol(-1) at 0 K. Our experimental results and the derived reaction mechanisms gain full support from electronic structure calculations on the singlet and triplet C(6)H(2) potential-energy surfaces. The identification of the 1,3,5-hexatriynyl radical under single collision conditions implies that the neutral-neutral reaction of dicarbon with diacetylene can lead to the formation of 1,3,5-hexatriynyl radicals in the interstellar medium and possibly in the hydrocarbon-rich atmospheres of planets and their moons such as Saturn's satellite Titan.
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Affiliation(s)
- Fangtong Zhang
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii 96822, USA
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16
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Páramo A, Canosa A, Le Picard SD, Sims IR. Rate Coefficients for the Reactions of C2(a3Πu) and C2(X1Σg+) with Various Hydrocarbons (CH4, C2H2, C2H4, C2H6, and C3H8): A Gas-Phase Experimental Study over the Temperature Range 24−300 K. J Phys Chem A 2008; 112:9591-600. [DOI: 10.1021/jp8025336] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Alejandra Páramo
- Institut de Physique de Rennes, UMR CNRS−Université n° 6251; Equipe ”Astrochimie Expérimentale”, Campus de Beaulieu, Bât. 11C, Université de Rennes 1, 35042 Rennes Cedex, France, and School of Chemistry, University of Birmingham, Edgbaston B15 2TT, Birmingham, U.K
| | - André Canosa
- Institut de Physique de Rennes, UMR CNRS−Université n° 6251; Equipe ”Astrochimie Expérimentale”, Campus de Beaulieu, Bât. 11C, Université de Rennes 1, 35042 Rennes Cedex, France, and School of Chemistry, University of Birmingham, Edgbaston B15 2TT, Birmingham, U.K
| | - Sébastien D. Le Picard
- Institut de Physique de Rennes, UMR CNRS−Université n° 6251; Equipe ”Astrochimie Expérimentale”, Campus de Beaulieu, Bât. 11C, Université de Rennes 1, 35042 Rennes Cedex, France, and School of Chemistry, University of Birmingham, Edgbaston B15 2TT, Birmingham, U.K
| | - Ian R. Sims
- Institut de Physique de Rennes, UMR CNRS−Université n° 6251; Equipe ”Astrochimie Expérimentale”, Campus de Beaulieu, Bât. 11C, Université de Rennes 1, 35042 Rennes Cedex, France, and School of Chemistry, University of Birmingham, Edgbaston B15 2TT, Birmingham, U.K
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Leonori F, Petrucci R, Segoloni E, Bergeat A, Hickson KM, Balucani N, Casavecchia P. Unraveling the dynamics of the C(3P,1D) + C2H2 reactions by the crossed molecular beam scattering technique. J Phys Chem A 2008; 112:1363-79. [PMID: 18229899 DOI: 10.1021/jp0776208] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
A detailed investigation of the dynamics of the reactions of ground- and excited-state carbon atoms, C(3P) and C(1D), with acetylene is reported over a wide collision energy range (3.6-49.1 kJ mol-1) using the crossed molecular beam (CMB) scattering technique with electron ionization mass spectrometric detection and time-of-flight (TOF) analysis. We have exploited the capability of (a) generating continuous intense supersonic beams of C(3P, 1D), (b) crossing the two reactant beams at different intersection angles (45, 90, and 135 degrees ) to attain a wide range of collision energies, and (c) tuning the energy of the ionizing electrons to low values (soft ionization) to suppress interferences from dissociative ionization processes. From angular and TOF distribution measurements of products at m/z=37 and 36, the primary reaction products of the C(3P) and C(1D) reactions with C2H2 have been identified to be cyclic (c)-C3H + H, linear (l)-C3H + H, and C3 + H2. From the data analysis, product angular and translational energy distributions in the center-of-mass (CM) system for both the linear and cyclic C3H isomers as well as the C3 product from C(3P) and for l/c-C3H and C3 from C(1D) have been derived as a function of collision energy from 3.6 to 49.1 kJ mol-1. The cyclic/linear C3H ratio and the C3/(C3 + c/l-C3H) branching ratios for the C(3P) reaction have been determined as a function of collision energy. The present findings have been compared with those from previous CMB studies using pulsed beams; here, a marked contrast is noted in the CM angular distributions for both C3H- and C3-forming channels from C(3P) and their trend with collision energy. Consequently, the interpretation of the reaction dynamics derived in the present work contradicts that previously proposed from the pulsed CMB studies. The results have been discussed in the light of the available theoretical information on the relevant triplet and singlet C3H2 ab initio potential energy surfaces (PESs). In particular, the branching ratios for the C(3P) + C2H2 reaction have been compared with the available theoretical predictions (approximate quantum scattering calculations and quasiclassical trajectory calculations on ab initio triplet PESs and, very recent, statistical calculations on ab initio triplet PESs as well as on ab initio triplet/singlet PESs including nonadiabatic effects, that is, intersystem crossing). While the experimental branching ratios have been corroborated by the statistical predictions, strong disagreement has been found with the results of the dynamical calculations. The astrophysical implications of the present results have been noted.
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Affiliation(s)
- Francesca Leonori
- Dipartimento di Chimica, Università degli Studi di Perugia, 06123 Perugia, Italy
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Daugey N, Caubet P, Bergeat A, Costes M, Hickson KM. Reaction kinetics to low temperatures. Dicarbon + acetylene, methylacetylene, allene and propene from 77 ≤ T ≤ 296 K. Phys Chem Chem Phys 2008; 10:729-37. [DOI: 10.1039/b710796j] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Gu X, Guo Y, Mebel AM, Kaiser RI. A crossed beam investigation of the reactions of tricarbon molecules, C3(X1Σg+), with acetylene, C2H2(X1Σg+), ethylene, C2H4(X1Ag), and benzene, C6H6(X1A1g). Chem Phys Lett 2007. [DOI: 10.1016/j.cplett.2007.10.041] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Kaiser RI, Belau L, Leone SR, Ahmed M, Wang Y, Braams BJ, Bowman JM. A Combined Experimental and Computational Study on the Ionization Energies of the Cyclic and Linear C3H Isomers. Chemphyschem 2007; 8:1236-9. [PMID: 17429825 DOI: 10.1002/cphc.200700109] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
For the first time, two hydrogen-deficient hydrocarbon radicals are generated in situ via laser ablation of graphite and seeding the ablated species in acetylene gas, which acts as a carrier and reactant simultaneously. By recording photoionization efficiency curves (PIE) and simulating the experimental spectrum with computed Franck-Condon (FC) factors, we can reproduce the general pattern of the PIE curve of m/z=37. We recover ionization energies of 9.15 eV and 9.76 eV for the linear and cyclic isomers, respectively. Our combined experimental and theoretical studies provide an unprecedented, versatile pathway to investigate the ionization energies of even more complex hydrocarbon radicals in situ, which are difficult to prepare by classical synthesis, in future experiments.
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Affiliation(s)
- Ralf I Kaiser
- University of Hawaii at Manoa, Department of Chemistry, Honolulu, HI 96822, USA.
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Gu X, Guo Y, Zhang F, Mebel AM, Kaiser RI. A crossed molecular beams study on the formation and energetics of the resonantly stabilized free i-C4H3(X2A′) radical and its isotopomers. Chem Phys 2007. [DOI: 10.1016/j.chemphys.2007.03.027] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Mebel AM, Kim GS, Kislov VV, Kaiser RI. The Reaction of Tricarbon with Acetylene: An Ab Initio/RRKM Study of the Potential Energy Surface and Product Branching Ratios. J Phys Chem A 2007; 111:6704-12. [PMID: 17391012 DOI: 10.1021/jp0690300] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ab initio calculations of the potential energy surface for the C3(1Sigmag+)+C2H2(1Sigmag+) reaction have been performed at the RCCSD(T)/cc-pVQZ//B3LYP/6-311G(d,p) + ZPE[B3LYP/6-311G(d,p)] level with extrapolation to the complete basis set limit for key intermediates and products. These calculations have been followed by statistical calculations of reaction rate constants and product branching ratios. The results show the reaction to begin with the formation of the 3-(didehydrovinylidene)cyclopropene intermediate i1 or five-member ring isomer i7 with the entrance barriers of 7.6 and 13.8 kcal/mol, respectively. i1 rearranges to the other C5H2 isomers, including ethynylpropadienylidene i2, singlet pentadiynylidene i3, pentatetraenylidene i4, ethynylcyclopropenylidene i5, and four- and five-member ring structures i6, i7, and i8 by ring-closure and ring-opening processes and hydrogen migrations. i2, i3, and i4 lose a hydrogen atom to produce the most stable linear isomer of C5H with the overall reaction endothermicity of approximately 24 kcal/mol. H elimination from i5 leads to the formation of the cyclic C5H isomer, HC2C3, +H, 27 kcal/ mol above C3+C2H2. 1,1-H2 loss from i4 results in the linear pentacarbon C5+H2 products endothermic by 4 kcal/mol. The H elimination pathways occur without exit barriers, whereas the H2 loss from i4 proceeds via a tight transition state 26.4 kcal/mol above the reactants. The characteristic energy threshold for the reaction under single collision conditions is predicted be in the range of approximately 24 kcal/mol. Product branching ratios obtained by solving kinetic equations with individual rate constants calculated using RRKM and VTST theories for collision energies between 25 and 35 kcal/mol show that l-C5H+H are the dominant reaction products, whereas HC2C3+H and l-C5+H2 are minor products with branching ratios not exceeding 2.5% and 0.7%, respectively. The ethynylcyclopropenylidene isomer i5 is calculated to be the most stable C5H2 species, more favorable than triplet pentadiynylidene i3t by approximately 2 kcal/mol.
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Affiliation(s)
- Alexander M Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, USA.
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Gu X, Guo Y, Zhang F, Kaiser RI. Investigating the Chemical Dynamics of the Reaction of Ground-State Carbon Atoms with Acetylene and Its Isotopomers. J Phys Chem A 2007; 111:2980-92. [PMID: 17385844 DOI: 10.1021/jp0674322] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
We investigated the multichannel reaction of ground-state carbon atoms with acetylene, C2H2 (X1Sigmag+), to form the linear and cyclic C3H isomers (atomic hydrogen elimination pathway) as well as tricarbon plus molecular hydrogen. The experiments were conducted under single-collision conditions at three different collision energies between 8.0 kJ mol-1 and 31.0 kJ mol-1. Our studies were complemented by crossed molecular beam experiments of carbon with three isotopomers C2D2(X1Sigmag+), C2HD (X1Sigma+), and 13C2H2 (X1Sigmag+) to clarify a potential intersystem crossing (ISC), the effect of the symmetry of the reaction intermediates on the center-of-mass angular distributions, the collision energy-dependent branching ratios of the atomic versus molecular hydrogen elimination pathways, and deuterium-enrichment processes. The results are discussed in light of recent electronic structure and dynamics calculations.
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Affiliation(s)
- Xibin Gu
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, USA
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