A study of the gas phase reactions of various cations with two derivatives of SF6; SF5CF3 and SF5Cl

Atterbury, C.; Critchley, A.; Kennedy, Richard A.; Mayhew, Chris A.; Tuckett, Richard P.

doi:10.1039/b109567f

Cited by 29 publications

(47 citation statements)

References 46 publications

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“…SF 5 Cl + h SF 5 + + Cl or SF 4 Cl + + F ), parallel to that reported by Mitsuke et al for SF 6 [16]. The kinetics of low-energy electron attachment, of anion, and of cation reactions with SF 5 Cl has been studied in recent years by Mayhew and co-workers [17][18][19].…”

Section: -3]supporting

confidence: 63%

Vacuum-UV and electron dissociative ionisation studies of SF5Cl

Chim

Cicman

Märk

et al. 2007

International Journal of Mass Spectrometry

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Section: -3]supporting

confidence: 63%

Vacuum-UV and electron dissociative ionisation studies of SF5Cl

Chim

Cicman

Märk

et al. 2007

International Journal of Mass Spectrometry

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“…This number is consistent with the ∆ f Hº 0 value for SF 4 Cl of -761 kJ mol -1 determined in previous SIFT work by our group on SF 5 Cl. 24 Another set of proposed neutrals is SF 4 + Cl, and if the well-established thermochemistry of these neutrals is used, this reaction is just exothermic. For the reaction with O 2 + , CHClF + can form with either ClOO or OClO on enthalpy grounds.…”

Section: Rate Coefficientsmentioning

confidence: 99%

Selected Ion Flow Tube Study of the Reactions between Gas Phase Cations and CHCl₂F, CHClF₂, and CH₂ClF

2005

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rate, but the reagent ions SF 3 + , NO + , NO 2 + and SF 2 + do not react. Surprisingly, although all of the observed product channels are calculated to be endothermic, H 3 O + does react with CHCl 2 F. On thermochemical grounds, Xe + appears to react with these molecules only when it is in its higher-energy 2 P 1/2 spin-orbit state. In general, most of the reactions form products by dissociative charge transfer, but some of the reactions of CH 2 ClF with the lower-energy cations produce the parent cation in significant abundance. The branching ratios produced in this study and by threshold photoelectron-photoion coincidence spectroscopy (preceding paper) agree reasonably well over the energy range 11 − 22 eV. In about one fifth of the large number of reactions studied the branching ratios are in excellent agreement and appreciable energy resonance between an excited state and the ground state of the ionized neutral exists, suggesting that these reactions proceed exclusively by a long-range charge transfer mechanism.Upper limits for the enthalpy of formation at 298 K of SF 4 Cl (−637 kJ mol -1 ), SClF (−28 kJ mol -1 ) and SHF (−7 kJ mol -1 ) are determined. 3 IntroductionThe study of ion-molecule reactions is of importance in many areas of science, such as plasmas found in industrial applications and in the interstellar medium. 1,2 These fundamental processes underpin the complex reactivity that is evident in these systems. One such mechanism is that of charge transfer, which can occur over either a long-range or a short-range. The former model states that as an ion (A + ) makes an approach toward a neutral reagent (BC), the ionic charge induces a dipole interaction in the neutral. At a critical separation between the two species, the potential curves of A + −BC and A−BC + cross, thus allowing an electron to jump from the neutral to the ion. Factors that exhibit a marked preference for the occurrence of this process include energy resonance between the ground electronic state and an ionic state of the neutral and the extent of shielding in the molecular orbital from which the electron is removed. A guide to the possible energy resonances can be found in the photoelectron spectrum (PES) of the neutral species. For the molecular reagent cations, the Franck-Condon factor for neutralising A + can also be important. If the long-range process is unfavourable, then the two species move closer together. The resulting intimate interaction can perturb the relevant potential surfaces to such an extent that a crossing is stimulated, thereby leading to short-range charge transfer. Note that, in this case, although the FranckCondon factors involved are perturbed, they still need to be appreciable in the isolated molecule for this process to transpire. Short-range charge transfer can compete with chemical reactions, where bonds are broken and formed. As neither a curve crossing nor a Franck-Condon factor is required for a chemical reaction to occur, this channel can proceed efficiently. A thorough review of the aforementioned ...

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“…The rate constants for reactions of SF 5 CF 3 with a large number of small cations have been measured in a selected ion flow tube apparatus at 298 K [7,8]. Most reactions proceed with rate constants close to the capture limit.…”

Section: Introductionmentioning

confidence: 99%

The vacuum-UV absorption spectrum of SF5CF3; implications for its lifetime in the earth’s atmosphere

Chim

Kennedy

Tuckett

2003

Chemical Physics Letters

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: Using vacuum-UV radiation from a synchrotron source, the absorption spectrum of SF 5 CF 3 has been measured in the range 50-150 nm at a resolution of 0.12 nm. The cross section at the Lyman-α wavelength of 121.6 nm is 1.5 ± 0.3 x 10 -17 cm 2 molecule -1 . The loss of SF 5 CF 3 on a molecular basis from the earth's atmosphere is dominated, not by photon-induced dissociation, but by electron attachment in the mesosphere above 60 km, yielding SF 5 -. The lifetime of SF 5 CF 3 in the earth's atmosphere, however, is determined primarily by the meterological conditions that transport it from the earth's surface to the mesosphere, and not by processes that occur in that region. By comparison with data for SF 6 , a lifetime of ca. 1000 years for SF 5 CF 3 is estimated.3

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A study of the gas phase reactions of various cations with two derivatives of SF6; SF5CF3 and SF5Cl

Cited by 29 publications

References 46 publications

Vacuum-UV and electron dissociative ionisation studies of SF5Cl

Vacuum-UV and electron dissociative ionisation studies of SF5Cl

Selected Ion Flow Tube Study of the Reactions between Gas Phase Cations and CHCl₂F, CHClF₂, and CH₂ClF

The vacuum-UV absorption spectrum of SF5CF3; implications for its lifetime in the earth’s atmosphere

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A study of the gas phase reactions of various cations with two derivatives of SF6; SF5CF3 and SF5Cl

Cited by 29 publications

References 46 publications

Vacuum-UV and electron dissociative ionisation studies of SF5Cl

Vacuum-UV and electron dissociative ionisation studies of SF5Cl

Selected Ion Flow Tube Study of the Reactions between Gas Phase Cations and CHCl2F, CHClF2, and CH2ClF

The vacuum-UV absorption spectrum of SF5CF3; implications for its lifetime in the earth’s atmosphere

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Selected Ion Flow Tube Study of the Reactions between Gas Phase Cations and CHCl₂F, CHClF₂, and CH₂ClF