Decomposition of hot radicals. Part 1. The production of CCl and CBr from halogen-substituted methyl radicals

Simons, J. P.; Yarwood, A. J.

doi:10.1039/tf9615702167

Cited by 59 publications

(18 citation statements)

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“…11,12 The present study finds that photodissociation of bromoform also releases Br 2 . The unanticipated Br 2 product channel is especially important because it sheds new light on the possible role of gas phase photochemistry of bromoform on atmospheric bromine chemistry.…”

Section: Discussionsupporting

confidence: 58%

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Ultraviolet photodissociation of bromoform at 234 and 267 nm by means of ion velocity imaging

Francisco

Huang

et al. 2002

The Journal of Chemical Physics

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Articles you may be interested inPhotodissociation of (SO2XH) Van der Waals complexes and clusters (XH = C2H2, C2H4, C2H6) excited at 32 040-32090 cm−1 with formation of HSO2 and XThe photochemistry of bromoform is of considerable importance to understanding the impact of short-lived halogen species on bromine chemistry in the atmosphere. In the present work, the products of the ultraviolet photodissociation of bromoform at 234 and 267 nm are determined by time-of-flight mass spectrometry and velocity ion imaging. Both ground Br ( 2 P 3/2 ) and spin-orbit excited Br ( 2 P 1/2 ) atoms are found to be formed via resonance-enhanced multiphoton ionization detection. Radical products are detected via vacuum ultraviolet photoionization at 118 nm. The results indicate that there is a primary molecule bromine elimination channel consisting of CHBr ϩBr 2 . The quantum yields for atomic Br and molecular Br 2 elimination channels are determined from the time-of-flight spectra to be 0.74 and 0.26 at 234 nm, respectively. At 267 nm, they are 0.84 and 0.16, respectively. Energy and angular distributions are deduced from the 2D images of Br, CHBr, and CHBr 2 . The direct studies described in this paper on the photodissociation of bromoform suggest that the current atmospheric photochemical models that do not anticipate the formation of Br 2 need to be reinvestigated to determine their implications for atmospheric bromine chemistry.

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Section: Discussionsupporting

confidence: 58%

“…11 Finally, multiphoton dissociative ionization of CBr and CHBr could give rise to the observed C ϩ and CH ϩ , since both CBr ϩ and CHBr ϩ ions are present. Multiphoton dissociation of CHBr 3 could be invoked as an explanation for the presence of CHBr and CBr.…”

Section: A Tof-ms Experimentsmentioning

confidence: 98%

Ultraviolet photodissociation of bromoform at 234 and 267 nm by means of ion velocity imaging

Francisco

Huang

et al. 2002

The Journal of Chemical Physics

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“…Ϫ1 . Its production requires at least two 193-nm photons to be absorbed by the CHBr 3 precursor which is thought to undergo Br atom loss as a primary photochemical event (23,24). A more plausible spin-allowed pathway would be secondary absorption of a 193-nm photon by the CHBr 2 radical intermediate that presumably has a larger absorption cross section than bromoform in its ground state.…”

Section: Table 1 Assigned Rotational Transitions In the Hcmentioning

confidence: 99%

Near-Infrared Spectroscopy of Bromomethylene in a Slit-Jet Expansion

Chang

Costen

Marr

et al. 2000

Journal of Molecular Spectroscopy

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“…It should be pointed out that this ratio would approach unity even more closely if we had been able to include the trace amounts of C 2 H 5 CI and C2H3Cl in calculating Re 2 H4Cl. Increased chloroform production as observed above could possibly be caused by reaction (11). The formation of 1, 4-dichlorobutane is explained by reaction (3).…”

Section: + Cci4---cch+chmentioning

confidence: 67%

“…The increase of ReCla/RC2H4Cl with increasing temperatures is discussed la ter. Considering the fact that the C-H bond in chloroform is only 93 kcal/mole compared to 104 kcal/mole for the C-H bond to be broken in ethylene, we feel that reaction (11) is not very plausible. Similarly it has been observed that 1,4dichlorobutane is a major reaction product if chlorine atoms are produced in the presence of ethylene by the photolysis of phosgene.!…”

Section: + Cci4---cch+chmentioning

confidence: 93%

Recombination and Disproportionation Reactions of Monochloroethyl and Trichloromethyl Radicals

Roquitte¹,

Wijnen²

1963

The Journal of Chemical Physics

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The recombination and disproportionation reactions of CH2CH2Cl and CCl3 radicals have been investigated. Trichloromethyl radicals and monochloroethyl radicals were produced by photolyzing carbon tetrachloride in the presence of ethylene. The main features of the resulting reaction mechanism are given by reactions (1) to (8) CCl4+hν→CCl3+Cl,Cl+C2H4→C2H4Cl,2C2H4Cl→(C2H4Cl)2,2C2H4Cl→C2H4+C2H4Cl2,2C2H4Cl→C2H5Cl+C2H3Cl,2CCl3→C2Cl6,C2H4Cl+CCl3→CCl3C2H4Cl,C2H4Cl+CCl3→CHCl3+C2H3Cl.The following rate constants have been determined k4/k3≤0.1;k5/k3≤0.1;k7/(k312k612)=2.5±0.2,and k8/k7=0.11±0.02.

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Decomposition of hot radicals. Part 1. The production of CCl and CBr from halogen-substituted methyl radicals

Cited by 59 publications

References 1 publication

Ultraviolet photodissociation of bromoform at 234 and 267 nm by means of ion velocity imaging

Ultraviolet photodissociation of bromoform at 234 and 267 nm by means of ion velocity imaging

Near-Infrared Spectroscopy of Bromomethylene in a Slit-Jet Expansion

Recombination and Disproportionation Reactions of Monochloroethyl and Trichloromethyl Radicals

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