Structures and Electron Attachment Properties of Halomethanes (CX n Y m , X = H, F; Y = Cl, Br, I; n = 0,4; m = 4n)

Roszak, Szczepan; Koski, W. S.; Kaufman, Joyce J.; Balasubramanian, K.

doi:10.1080/10629360108035360

Cited by 13 publications

(5 citation statements)

References 29 publications

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“…The direct dissociation by electron impact (reaction 8) for the halomethanes can take place by dissociative electron attachment when an electron goes into the antibonding orbital, leading to dissociation of the molecule into a radical and a halide ion which is rapidly charge neutralized . Compounds such as CCl 4 − and CF 2 Cl 2 ,, exhibit large cross-sections for dissociative electron attachment.…”

Section: Discussionmentioning

confidence: 99%

NO_x Formation in the Plasma Treatment of Halomethanes

2005

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A nonthermal, atmospheric pressure plasma, made-up of a BaTiO3 packed-bed reactor, has been used to study the formation of NOx and N2O during the plasma destruction of a range of volatile organic compounds (VOCs) and hazardous air pollutants, including chlorinated, brominated, fluorinated, and iodinated methane species, in a carrier gas of air. Using the plasma destruction of pure air as a baseline, it is found that the amount of NOx formed is unaffected by the addition of a few hundred parts per million of a simple hydrocarbon (e.g. methane). In the case of the fluorinated, chlorinated, and brominated methanes, we find enhanced production of NOx and a marked increase in the ratio of NO2 to NO formed, from approximately 1.1 in air and methane to approximately 2.3 in halogenated species. However, iodinated additives (specifically methyl iodide and diiodomethane) have remarkably different results compared to the other halogenated additives; they show enhanced increases in the NO2 to NO ratio ( approximately 6-13) and reduced NOx production. The enhanced conversion of NO to NO2 is attributed to reactions involving halogen oxides, e.g. ClO and IO.

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Section: Discussionmentioning

confidence: 99%

NO_x Formation in the Plasma Treatment of Halomethanes

2005

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“…Following earlier work [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27], dissociative electron attachment experiments on the carbon, silicon and germanium tetrafluorides were reported by Bjarnason et al [28], and on the corresponding * Email: fritz@unb.ca tetrabromides by Omarsson et al [29]. Theoretical studies on fluorides and chlorides have been performed by Gutsev et al [30][31][32][33][34][35][36], Bonazolla et al [15], Roszak et al [37,38], King et al [39], Tachikawa et al [40,41], Li et al [42] and Wang and Zhang [43]. Details will be given in later sections, together with our results.…”

Section: Introductionmentioning

confidence: 94%

Structure and properties of the anions MF₄⁻, MCl₄⁻and MBr₄⁻(M = C, Si, Ge)

Grein

2014

Molecular Physics

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Density functional theory (DFT), Møller-Plesset (MP2) and coupled cluster with single and double substitutions including non-iterative triple excitations (CCSD(T)) calculations on the anions MX 4 − , with M = C, Si, Ge and X = F, Cl, Br, show that GeF 4 − , SiCl 4 − , GeCl 4 − and SiBr 4 − prefer a C 2v conformation, but CCl 4 − is an elongated C 3v structure. CBr 4 − has T d symmetry in MP2, but is slightly more stable in elongated C 3v form with DFT and CCSD(T). GeBr 4 − has T d symmetry. CF 4 − and SiF 4 − are unstable with respect to loss of an electron. Vertical electron affinities (EAs) are negative also for CCl 4 and SiCl 4 , and close to zero for GeF 4 and SiBr 4 . Adiabatic EAs range from 0.47 eV for SiCl 4 to 1.78 eV for GeBr 4 . The lowest excited states at T d symmetry are 2 T 2 resonances with energies of 2.1-3.5 eV, resulting from excitation of the a 1 singly occupied molecular orbital to vacant t 2 orbitals. Vertical excitation energies (VEEs) and vibrational frequencies are given for the most stable anionic geometries. Comparison with experimental VEEs for CCl 4 − is made. From dissociation energies of MX 4 , MX 4 − , MX 3 and MX 3 − , appearance energies of X − , MX 3 − , X 2 − and MX 2 − were calculated. Most were found to be in reasonable agreement with experimental values. Theoretical spin densities and g-factors have been compared with experimental results available for CCl 4 − , SiCl 4 − and GeCl 4 − .

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“…12,15 In particular, electron attachment is found to be the primary process resulting in the toxicity of halocarbons, 16 and DEA plays an important role in combustion inhibition, zerovalent metal remediation and bioremediation. 17 Dehalogenation is generally initiated by a reductive transformation also in anoxic systems, 18 where the halogenated compound behaves as an electron acceptor, i.e., the whole reaction is driven by an electron transfer process.…”

Section: Introductionmentioning

confidence: 99%

Degradation of gas phase decabromodiphenyl ether by resonant interaction with low-energy electrons

Pshenichnyuk

Lomakin

Modelli

2011

Phys. Chem. Chem. Phys.

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Resonance electron attachment in a series of brominated phenyl ethers, including decabromodiphenyl ether (DBDE), was investigated in the gas phase by means of electron transmission spectroscopy (ETS) and dissociative electron attachment spectroscopy (DEAS). Attachment of thermal electrons to DBDE leads to various dissociative decay channels of the temporary molecular anion. In contrast to other bromophenyl ethers, the bromide anion is not the most intense negative fragment. The neutral counterparts of the observed [Br(2)](-) and [C(6)Br(4)O](-) anion fragments are ascribed to the closed-shell species octabromodibenzofuran and hexabromobenzene, respectively, although their formation implies complex atomic rearrangements. Density functional theory calculations are employed to evaluate electron affinities, thermodynamic energy thresholds for production of the anion fragments observed in the DEA spectra and the proton affinities of the corresponding neutral radicals. Since DBDE is one of the most widespread organic pollutants, the present gas-phase DEA study can provide indications on the reaction mechanisms which occur in vivo and cause injuries to living cells.

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Structures and Electron Attachment Properties of Halomethanes (CX _n Y _m, X = H, F; Y = Cl, Br, I; n = 0,4; m = 4n)

Cited by 13 publications

References 29 publications

NO_x Formation in the Plasma Treatment of Halomethanes

NO_x Formation in the Plasma Treatment of Halomethanes

Structure and properties of the anions MF₄⁻, MCl₄⁻and MBr₄⁻(M = C, Si, Ge)

Degradation of gas phase decabromodiphenyl ether by resonant interaction with low-energy electrons

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Structures and Electron Attachment Properties of Halomethanes (CX n Y m , X = H, F; Y = Cl, Br, I; n = 0,4; m = 4n)

Cited by 13 publications

References 29 publications

NOx Formation in the Plasma Treatment of Halomethanes

NOx Formation in the Plasma Treatment of Halomethanes

Structure and properties of the anions MF4−, MCl4−and MBr4−(M = C, Si, Ge)

Degradation of gas phase decabromodiphenyl ether by resonant interaction with low-energy electrons

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Product

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Structures and Electron Attachment Properties of Halomethanes (CX _n Y _m, X = H, F; Y = Cl, Br, I; n = 0,4; m = 4n)

NO_x Formation in the Plasma Treatment of Halomethanes

NO_x Formation in the Plasma Treatment of Halomethanes

Structure and properties of the anions MF₄⁻, MCl₄⁻and MBr₄⁻(M = C, Si, Ge)