Temporary negative ions in the chloromethanes CHCl2F and CCl2F2: Characterization of the σ* orbitals

Burrow, Paul; Modelli, Alberto; Chiu, N. S.; Jordan, Kenneth D.

doi:10.1063/1.444103

Cited by 150 publications

(124 citation statements)

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“…CHCl 3 and 1,1,1-trichloroethane Figures 9 and 10 show the DEA results for these two closely related molecules on both linear and semi-log scales. The two low-lying temporary anion states of CHCl 3 , arising from the three C-Cl * orbitals, have been observed previously 14 and assigned to the 2 A 1 state and the doubly degenerate 2 E state. Our recent ETS measurements 4 place these states at 0.42 and 1.8 eV, respectively.…”

Section: B Dea In Selected Trichloroalkanesmentioning

confidence: 92%

“…This suggests that the major source of the s-wave attachment in this compound arises from the 2 A 1 ground state of the anion, which is bound at the equilibrium geometry of the neutral molecule, 14 rather than from the 2 T state.…”

Section: B Dea Peaks Appearing At Zero Electron Energymentioning

confidence: 99%

“…The VAE associated with occupation of the LUMO of CCl 4 is negative 14 and not observable by ETS. Attachment into the next higher empty orbital, the triply degenerate t orbital, takes place at 0.94 eV, 14 and gives rise to a peak in the DEA cross section at 0.80 eV.…”

mentioning

confidence: 98%

“…Attachment into the next higher empty orbital, the triply degenerate t orbital, takes place at 0.94 eV, 14 and gives rise to a peak in the DEA cross section at 0.80 eV. 10 Owing to the large zero energy cross section of CCl 4 and the difficulty of removing traces of this compound from the vacuum system, we have not remeasured it.…”

mentioning

confidence: 99%

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Total cross sections for dissociative electron attachment in dichloroalkanes and selected polychloroalkanes: The correlation with vertical attachment energies

Aflatooni

Burrow

2000

The Journal of Chemical Physics

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Electron attachment into the lowest unoccupied molecular orbital of a typical polychloroalkane in the gas phase forms a temporary negative ion in which the impinging electron resides on a combination of local C-Cl * orbitals. Because of the antibonding character of these orbitals, these anions may dissociate, producing Cl Ϫ with cross sections that vary enormously over the chloroalkane family. In this work, we present absolute total dissociative electron attachment ͑DEA͒ cross sections for 33 of these compounds, and we show that the peak values of the cross sections correlate strongly with the vertical attachment energies ͑VAEs͒ for formation of the lowest anion states at the equilibrium geometries of the neutral molecules. This behavior is a consequence of the remarkably monotonic dependence of the resonance widths of the temporary anion states on VAE over the range 0.42ϽVAEϽ3.45 eV. Finally, we note also the strong connection between the s-wave attachment process at 0 eV in these compounds and the VAEs associated with the nearby anion states.

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Section: B Dea In Selected Trichloroalkanesmentioning

confidence: 92%

Section: B Dea Peaks Appearing At Zero Electron Energymentioning

confidence: 99%

mentioning

confidence: 98%

mentioning

confidence: 99%

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Total cross sections for dissociative electron attachment in dichloroalkanes and selected polychloroalkanes: The correlation with vertical attachment energies

Aflatooni

Burrow

2000

The Journal of Chemical Physics

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“…1. As discussed elsewhere, 19 the VAE associated with adding an electron into the LUMO of CCl 4 is negative, that is, the 2 A 1 ground state of the anion is vertically stable and thus inaccessible by ETS. There is no consensus for the VAE of this state.…”

Section: Integrated Zero Peak Cross Sectionsmentioning

confidence: 99%

Dissociative electron attachment near threshold, thermal attachment rates, and vertical attachment energies of chloroalkanes

Gallup

Aflatooni

Burrow

2003

The Journal of Chemical Physics

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The peaks appearing near zero energy in the dissociative electron attachment cross section of 18 chloroalkanes are studied by electron beam methods. Fits to the experimental data are made using model cross sections having appropriate energy dependences and inclusion of the broadening due to the electron energy distribution. The magnitudes of the zero peaks are found to be well correlated with the vertical attachment energies ͑VAE͒ associated with occupation of the lowest empty orbitals of the compounds. The magnitudes rise exponentially by more than five orders of magnitude as VAE decreases from 2 eV to a slightly negative value. This dependence is a consequence not only of the thermal population of vibrational levels, but also of an approximately linear relationship between VAE and the energy of the crossing between the neutral and anion potential curves. Franck-Condon factors for the transition to the anion curve are computed for model potential curves, and the nature of the attachment from vibrational levels with energies near that of the crossing point is explored in a local potential resonance picture. A substantial contribution arises from tunneling to the anion state from vibrational levels below the barrier. Thermal attachment rate constants are also computed from our data. These are also shown to vary exponentially with VAE.

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Competing electron transfer, proton abstraction and nucleophilic substitutions in gas-phase reactions of (radical) anions with chloro- and bromomethanes

Staneke

Groothuis

Ingemann

et al. 1996

J. Phys. Org. Chem.

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Competing electron transfer proton abstraction and nucleophilic substitutions in gas-phase reactions of (radical) anions with chloro-and bromomethanes. Staneke, P.O.; Groothuis, G.; Ingemann Jorgensen, S.; Nibbering, N.M.M. (1996). Competing electron transfer proton abstraction and nucleophilic substitutions in gas-phase reactions of (radical) anions with chloroand bromomethanes. Journal of physical organic chemistry, 9, 471-486. 3.0.CO;2-I" class="link">https://doi.org/10.1002/(SICI)1099-1395(199607)9:73.0.CO;2-I General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. The product ion distributions and rates of the gas-phase reactions of two series of (radical) anions with chloroand bromomethanes (CH,CI, CH,CI,, CHC13, CCI,, CH,Br, CHzBr2, CHBr, and CBr,) were determined with the use of Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry. The first series consists of anions (HO-, CH30-, C,H,O-, C,H,O-and CH S-), for which the corresponding neutral radicals have a relatively high electron affinity (EA >150 Wmol-). The second series consists of (radical) anions (CH2S-', CH,-CHCH,-, CH,--C(CH,)CH,-, CJ3,-' and C,H,-), for which the corresponding neutral species have a relatively low electron affinity (EA s 100 kJmol-I). These (radical) anions react mainly with the halomethanes to afford (i) halide ions, (ii) halomethyl anions with the same number of halogen atoms as in the parent halomethane and (iii) halomethyl anions with one halogen atom less than the parent substrate. The last process involves nucleophilic attack on a halogen atom and is particularly important in the reactions with substrates containing three or four halogen atoms. The halide ions may arise by a number of different pathways, such as SN2 substitution, a-elimination, halogen attack followed by dissociation of the thus formed halomethyl anion and overall dissociative electron transfer. The SN2 process is held responsible for the formation of halide ions in the reactions with monohalomethanes, whereas a-elimination is likely to be of importance only for the reactions with trichloro-and tribromomethanes. Attack on a halogen atom followed by dissociation of the ion generated initially is likely to be important if CCI, or CBr, is the substrate. Electron transfer is only a dominant pathway in ...

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Temporary negative ions in the chloromethanes CHCl2F and CCl2F2: Characterization of the σ* orbitals

Abstract: The electron transmission spectra of chlorometers CHCl2F and CCl2F2 are presented. The electron affinities are evaluted compared with thoses calculated using self-consistent field methods. (AIP)

Cited by 150 publications

References 11 publications

Total cross sections for dissociative electron attachment in dichloroalkanes and selected polychloroalkanes: The correlation with vertical attachment energies

Total cross sections for dissociative electron attachment in dichloroalkanes and selected polychloroalkanes: The correlation with vertical attachment energies

Dissociative electron attachment near threshold, thermal attachment rates, and vertical attachment energies of chloroalkanes

Competing electron transfer, proton abstraction and nucleophilic substitutions in gas-phase reactions of (radical) anions with chloro- and bromomethanes

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