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Hua L, Lee WB, Chao MH, Zhang B, Lin KC. Elimination mechanisms of Br2+ and Br+ in photodissociation of 1,1- and 1,2-dibromoethylenes using velocity imaging technique. J Chem Phys 2011; 134:194312. [DOI: 10.1063/1.3584178] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Zou P, Strecker KE, Ramirez-Serrano J, Jusinski LE, Taatjes CA, Osborn DL. Ultraviolet photodissociation of vinyl iodide: understanding the halogen dependence of photodissociation mechanisms in vinyl halides. Phys Chem Chem Phys 2009; 10:713-28. [PMID: 19791455 DOI: 10.1039/b712117b] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The photodissociation of vinyl iodide has been investigated at several wavelengths between 193 and 266 nm using three techniques: time-resolved Fourier transform emission spectroscopy, multiple pass laser absorption spectroscopy, and velocity-mapped ion imaging. The only dissociation channel observed is C-I bond cleavage to produce C2H3 (nu, N) + I (2P(J)) at all wavelengths investigated. Unlike photodissociation of other vinyl halides (C2H3X, X = F, Cl, Br), in which the HX product channel is significant, no HI elimination is observed. The angular and translational energy distributions of I atoms indicate that atomic products arise solely from dissociation on excited states with negligible contribution from internal conversion to the ground state. We derive an upper limit on the C-I bond strength of D0(C2H3-I) < or = 65 kcal mol(-1). The ground-state potential-energy surface of vinyl iodide is explored by ab initio calculations. We present a model in which the highest occupied molecular orbital in vinyl halides has increasing X(np) non-bonding character with increasing halogen mass. This change leads to reduced torsional force around the C-C bond in the excited state. Because the ground-state energy is highest when the CH2 plane is perpendicular to the CHX plane, a reduced torsional force in the excited state correlates with a lower rate for internal conversion compared to excited-state C-X bond fission. This model explains the gradual change in photodissociation mechanisms of vinyl halides from the dominance of internal conversion in vinyl fluoride to the dominance of excited-state dissociation in vinyl iodide.
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Affiliation(s)
- Peng Zou
- Combustion Research Facility, Sandia National Laboratories, PO Box 969, Livermore, CA 94551-0969, USA
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Chang YP, Lee PC, Lin KC, Huang CH, Sun BJ, Chang AHH. Photodissociation of 1,2-Dibromoethylene at 248 nm: Br2 Molecular Elimination Probed by Cavity Ring-Down Absorption Spectroscopy. Chemphyschem 2008; 9:1137-45. [DOI: 10.1002/cphc.200700861] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Martínez-Núñez E, Vázquez S. Rovibrational distributions of HF in the photodissociation of vinyl fluoride at 193 nm: a direct MP2 quasiclassical trajectory study. J Chem Phys 2006; 121:5179-82. [PMID: 15352810 DOI: 10.1063/1.1782531] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Quasiclassical trajectory calculations were performed to calculate rovibrational distributions of the nascent HF fragment in the photodissociation of vinyl fluoride at 193 nm. The trajectories were initiated at the transition states of the four-center (4C) and three-center (3C) HF elimination channels, using a microcanonical, quasiclassical normal-mode sampling. In general, the calculated distributions are in reasonably good agreement with experiment. In particular, the trajectory distributions show bimodal character, although not as pronounced as that observed experimentally. The calculations predict that the 3C and 4C distributions are rather similar to each other, which suggests that the low-J and high-J components of the rotational distributions cannot be specifically assigned to each of these channels.
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Affiliation(s)
- Emilio Martínez-Núñez
- Departamento de Quimica Fisica, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain
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Martínez-Núñez E, Vázquez S. Quasiclassical trajectory calculations on the photodissociation of CF2CHCl at 193 nm: product energy distributions for the HF and HCl eliminations. J Chem Phys 2006; 122:104316. [PMID: 15836324 DOI: 10.1063/1.1859276] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Quasiclassical trajectory calculations were carried out to determine product energy distributions for the HCl and HF eliminations that take place in the photodissociation of 2-chloro-1,1-difluoroethylene at 193 nm. The trajectories were initiated at the transition states of the HCl and HF elimination channels under microcanonical, quasiclassical conditions, and were propagated with the energies and gradients taken directly from density functional theory calculations. Good agreement with experiment is found, except for the translational energy distribution of the HF elimination channel and the average vibrational energy of the HCl fragment. Possible sources of disagreement are discussed.
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Affiliation(s)
- Emilio Martínez-Núñez
- Departamento de Química Física, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain
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Zou P, Klippenstein SJ, Osborn DL. The Vinyl + NO Reaction: Determining the Products with Time-Resolved Fourier Transform Spectroscopy. J Phys Chem A 2005; 109:4921-9. [PMID: 16833839 DOI: 10.1021/jp050093c] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have studied the vinyl + NO reaction using time-resolved Fourier transform emission spectroscopy, complemented by electronic structure and microcanonical RRKM rate coefficient calculations. To unambiguously determine the reaction products, three precursors are used to produce the vinyl radical by laser photolysis: vinyl bromide, methyl vinyl ketone, and vinyl iodide. The emission spectra and theoretical calculations indicate that HCN + CH2O is the only significant product channel for the C2H3 + NO reaction near room temperature, in contradiction to several reports in the literature. Although CO emission is observed when vinyl bromide is used as the precursor, it arises from the reaction of NO with photofragments other than vinyl. This conclusion is supported by the absence of CO emission when vinyl iodide or methyl vinyl ketone is used. Prompt emission from vibrationally excited NO is evidence of the competition between back dissociation and isomerization of the initially formed nitrosoethylene adduct, consistent with previous work on the pressure dependence of this reaction. Our calculations indicate that production of products is dominated by the low energy portion of the energy distribution. The calculation also predicts an upper bound of 0.19% for the branching ratio of the H2CNH + CO channel, which is consistent with our experimental results.
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Affiliation(s)
- Peng Zou
- Combustion Research Facility, Sandia National Laboratories, P.O. Box 969, Livermore, California 94551-0969, USA
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Affiliation(s)
- John E Baldwin
- Department of Chemistry, Syracuse University, Syracuse, New York 13203, USA
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Affiliation(s)
- Patricia Ann Laws
- Department of Chemistry, Acadia University, Wolfville, Nova Scotia B0P 1X0
| | - John M. Roscoe
- Department of Chemistry, Acadia University, Wolfville, Nova Scotia B0P 1X0
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Castillejo M, Martín M, de Nalda R, Couris S, Koudoumas E. Anisotropic Distributions of Ion Fragments Produced by Dissociative Ionization of Halogenated Ethylenes in Intense Laser Fields. J Phys Chem A 2002. [DOI: 10.1021/jp013446q] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Castillejo M, Martı́n M, de Nalda R, Couris S, Koudoumas E. Dissociative ionization of halogenated ethylenes in intense femtosecond laser pulses. Chem Phys Lett 2002. [DOI: 10.1016/s0009-2614(02)00039-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Lee YR, Chou CC, Lee YJ, Wang LD, Lin SM. Photodissociation of 1,2-C2H2Br2 at 248 nm: Competition between three-body formation Br+Br+C2H2 and molecular Br2 elimination. J Chem Phys 2001. [DOI: 10.1063/1.1387476] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Lin SR, Lin SC, Lee YC, Chou YC, Chen IC, Lee YP. Three-center versus four-center elimination in photolysis of vinyl fluoride and vinyl bromide at 193 nm: Bimodal rotational distribution of HF and HBr (v⩽5) detected with time-resolved Fourier transform spectroscopy. J Chem Phys 2001. [DOI: 10.1063/1.1343079] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Laws PA, Hayley BD, Anthony LM, Roscoe JM. Kinetic Study of the Mechanism of the Low-Temperature Pyrolysis of Vinyl Bromide. J Phys Chem A 2001. [DOI: 10.1021/jp0031911] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Patricia Ann Laws
- Department of Chemistry, Acadia University, Wolfville, Nova Scotia, Canada B0P 1X0
| | - Bradley D. Hayley
- Department of Chemistry, Acadia University, Wolfville, Nova Scotia, Canada B0P 1X0
| | - Lori M. Anthony
- Department of Chemistry, Acadia University, Wolfville, Nova Scotia, Canada B0P 1X0
| | - John M. Roscoe
- Department of Chemistry, Acadia University, Wolfville, Nova Scotia, Canada B0P 1X0
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Rahaman A, Raff LM. Theoretical Investigations of Intramolecular Energy Transfer Rates and Pathways for Vinyl Bromide on an ab Initio Potential-Energy Surface. J Phys Chem A 2000. [DOI: 10.1021/jp001696l] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Asif Rahaman
- Department of Chemistry, Oklahoma State University, Stillwater, Oklahoma 74078
| | - Lionel M. Raff
- Department of Chemistry, Oklahoma State University, Stillwater, Oklahoma 74078
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Martínez-Núñez E, Vázquez SA. Classical Dynamics Study of the Unimolecular Decomposition of CH3SH+. J Phys Chem A 1999. [DOI: 10.1021/jp992243n] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Emilio Martínez-Núñez
- Departamento de Química Física, Universidad de Santiago de Compostela, Santiago de Compostela E−15706, Spain
| | - Saulo A. Vázquez
- Departamento de Química Física, Universidad de Santiago de Compostela, Santiago de Compostela E−15706, Spain
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Samoudi B, Dı́az L, Oujja M, Santos M. Real time study of the infrared multiphoton dissociation of vinylbromide. J Photochem Photobiol A Chem 1999. [DOI: 10.1016/s1010-6030(99)00078-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Peña-Gallego A, Martı́nez-Núñez E, Vázquez SA. Nonstatistical effects in the unimolecular dissociation of the acetyl radical. J Chem Phys 1999. [DOI: 10.1063/1.479073] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
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Martı́nez-Núñez E, Vázquez SA. Dynamical study of the dissociation and elimination channels in the decomposition of methyl nitrite. J Chem Phys 1998. [DOI: 10.1063/1.477561] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
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Katayanagi H, Yonekuira N, Suzuki T. C–Br bond rupture in 193 nm photodissociation of vinyl bromide. Chem Phys 1998. [DOI: 10.1016/s0301-0104(98)00085-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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