Electron-driven chemistry of halogenated compounds in condensed phases: Effects of solvent matrices on reaction dynamics and kinetics

Perry, Christopher C.; Faradzhev, N. S.; Fairbrother, D. Howard; Madey, Theodore E.

doi:10.1080/01442350412331284625

Cited by 24 publications

(22 citation statements)

References 109 publications

(263 reference statements)

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“…Based on the long lifetime of excess electrons at ice surfaces, it has been hypothesized that, in ice stratospheric clouds, excess electrons produced by cosmic rays, may catalyze some of the chemical reactions that lead to the formation of the radical halogen species responsible for the decomposition of ozone [2,3]. The relevance of this process to the depletion of the antarctic ozone is still under dispute [14 -16]; but its broader impact onto the rich electron-driven chemistry of condensed halogenated compounds is discussed, e.g., in [17].Stabilization of the EE in a surface-bound state is likely to be associated with a structural reorganization of the surface molecular layers. Accurate theoretical studies in very small clusters, up to H 2 O 12 , indicate that the presence of the EE modifies substantially the molecular structure of the cluster with respect to the neutral case [12].…”

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confidence: 99%

Surface Trapped Excess Electrons on Ice

2005

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Local trapping of excess electrons at the surface of solid water systems has recently been observed in large water clusters and at the ice/vacuum interface. The existence of stable surface-bound states for the excess electron may have important implications in atmospheric chemistry, electrochemistry, and radiation physics. By means of first-principles molecular dynamics we find that excess electrons induce a structural reconstruction of the ice surface on a time scale of a fraction of a picosecond. The surface molecular rearrangement leads to an increase of the number of dangling OH bonds pointing towards the vacuum and to the appearance of an electrostatic barrier preventing the penetration of the electron in the bulk. Both factors imply a remarkable stability for the surface-bound excess electron, with respect to its decay into the bulk solvated state.

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confidence: 99%

Surface Trapped Excess Electrons on Ice

2005

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“…The similar conclusion has been obtained by Perry et al using a combination of reflection absorption infrared spectroscopy, x-ray photoelectron spectroscopy, and temperature programmed desorption. 7,8 During x-ray irradiation, the dominance of Cl − anions was formed by the reaction with low-energy secondary electrons. They concluded that that C-Cl bond cleavage of CF 2 Cl 2 via dissociative electron attachment ͓reaction ͑2͔͒ is the dominant initial process.…”

Section: Introductionmentioning

confidence: 99%

Reaction dynamics following electron capture of chlorofluorocarbon adsorbed on water cluster: A direct density functional theory molecular dynamics study

Tachikawa

Abe

2007

The Journal of Chemical Physics

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The electron capture dynamics of halocarbon and its water complex have been investigated by means of the full dimensional direct density functional theory molecular dynamics method in order to shed light on the mechanism of electron capture of a halocarbon adsorbed on the ice surface. The CF 2 Cl 2 molecule and a cyclic water trimer ͑H 2 O͒ 3 were used as halocarbon and water cluster, respectively. The dynamics calculation of CF 2 Cl 2 showed that both C-Cl bonds are largely elongated after the electron capture, while one of the Cl atoms is dissociated from CF 2 Cl 2 − as a Cl − ion. Almost all total available energy was transferred into the internal modes of the parent CF 2 Cl radical on the product state, while the relative translational energy of Cl − was significantly low due to the elongation of two C-Cl bonds. In the case of a halocarbon-water cluster system, the geometry optimization of neutral complex CF 2 Cl 2 ͑H 2 O͒ 3 showed that one of the Cl atoms interacts with n orbital of water molecules of trimer and the other Cl atom existed as a dangling Cl atom. After the electron capture, only one C-Cl bond ͑dangling Cl atom͒ was rapidly elongated, whereas the other C-Cl bond is silent during the reaction. The dangling Cl atom was directly dissociated from CF 2 Cl 2 − ͑H 2 O͒ 3 as Cl − . The fast Cl − ion was generated from CF 2 Cl 2 − ͑H 2 O͒ 3 on the water cluster. The mechanism of the electron capture of halocarbon on water ice was discussed on the basis of the theoretical results.

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“…Instead of using a constant precursor flux during the exposure to electrons ͑as in the typical FEBIP experiment͒, a precursor film can be condensed onto a cooled substrate. 17,18 As soon as the desired film thickness ͓generally one or a few monolayers ͑MLs͔͒ is reached, the gas flow can be stopped. Analysis of the reaction products can be performed either during or after the electron exposure.…”

Section: Introductionmentioning

confidence: 99%

Electron induced dissociation of trimethyl (methylcyclopentadienyl) platinum (IV): Total cross section as a function of incident electron energy

Dorp

Wnuk

Gorham

et al. 2009

Journal of Applied Physics

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Electron induced dissociation of trimethyl (methylcyclopentadienyl) platinum (IV): Total cross section as a function of incident electron energyCite as: J. Appl. Phys. 106, 074903 (2009) The total cross section has been measured for the electron induced dissociation of trimethyl ͑methylcyclopentadienyl͒ platinum ͑IV͒ ͓MeCpPt͑IV͒Me 3 ͔, a Pt precursor often used in focused electron beam induced processing ͑FEBIP͒, for incident electron energies ranging between 3-3 keV. Measurements were performed for the precursor in the adsorbed state under ultrahigh vacuum conditions. The techniques used in this study were temperature programmed desorption, x-ray photoelectron spectroscopy and mass spectrometry. Two surfaces were used in these experiments, amorphous carbon overlayers containing embedded Pt atoms ͑a:C-Pt͒, formed by the electron decomposition of the Pt precursor, and atomically clean Au. The results from these three experiments revealed a comparatively low total cross section at 8 eV ͑4.2Ϯ 0.3ϫ 10 −17 cm 2 on the a:C-Pt and 1.4Ϯ 0.1ϫ 10 −17 cm 2 on the Au͒ that increases with increasing incident electron energy, reaching a maximum at around 150 eV ͑4.1Ϯ 0.5ϫ 10 −16 cm 2 on the a:C-Pt and 2.3Ϯ 0.2 ϫ 10 −16 cm 2 on the clean Au͒, before decreasing at higher incident electron energies, up to 3000 eV. Differences in the measured cross sections between Au and a:C-Pt surfaces demonstrate that the substrate can influence the reaction cross section of adsorbed species. Temperature programmed desorption was also used to measure the adsorption energy of MeCpPt͑IV͒Me 3 , which was found to depend on both the substrate and the adsorbate coverage. The work in this paper demonstrates that surface science techniques can be used to quantitatively determine the total cross section of adsorbed FEBIP precursors for electron induced dissociation as a function of incident electron energy. These total cross section values are necessary to obtain quantitatively accurate information from FEBIP models and to compare the reaction efficiencies of different precursors on a quantitative basis.

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Electron-driven chemistry of halogenated compounds in condensed phases: Effects of solvent matrices on reaction dynamics and kinetics

Cited by 24 publications

References 109 publications

Surface Trapped Excess Electrons on Ice

Surface Trapped Excess Electrons on Ice

Reaction dynamics following electron capture of chlorofluorocarbon adsorbed on water cluster: A direct density functional theory molecular dynamics study

Electron induced dissociation of trimethyl (methylcyclopentadienyl) platinum (IV): Total cross section as a function of incident electron energy

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