Atmospheric chemistry with synchrotron radiation

Mason, Nigel J.; Dawes, Anita; Mukerji, R. J.; Drage, E. A.; Vasekova, E.; Webb, Sarah; Limão-Vieira, P.

doi:10.1088/0953-4075/38/9/027

Cited by 19 publications

(21 citation statements)

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“…1 The present work is part of a wider research programme aimed at understanding the spectroscopy of sulphur-containing species and the role of these gases in atmospheric chemistry and physics (see, e.g., Refs. [2][3][4]. In order to model these processes in the stratosphere and troposphere, absolute photoabsorption cross sections (oscillator strengths) of such compounds are needed as well as a detailed knowledge of their electronic state spectroscopy.…”

Section: Introductionmentioning

confidence: 99%

Electronic excitation of carbonyl sulphide (COS) by high-resolution vacuum ultraviolet photoabsorption and electron-impact spectroscopy in the energy region from 4 to 11 eV

Limão-Vieira

Silva

Almeida

et al. 2015

The Journal of Chemical Physics

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The electronic state spectroscopy of carbonyl sulphide, COS, has been investigated using high resolution vacuum ultraviolet photoabsorption spectroscopy and electron energy loss spectroscopy in the energy range of 4.0–10.8 eV. The spectrum reveals several new features not previously reported in the literature. Vibronic structure has been observed, notably in the low energy absorption dipole forbidden band assigned to the (4π←3π) (1Δ←1Σ+) transition, with a new weak transition assigned to (1Σ−←1Σ+) reported here for the first time. The absolute optical oscillator strengths are determined for ground state to 1Σ+ and 1Π transitions. Based on our recent measurements of differential cross sections for the optically allowed (1Σ+ and 1Π) transitions of COS by electron impact, the optical oscillator strength f0 value and integral cross sections (ICSs) are derived by applying a generalized oscillator strength analysis. Subsequently, ICSs predicted by the scaling are confirmed down to 60 eV in the intermediate energy region. The measured absolute photoabsorption cross sections have been used to calculate the photolysis lifetime of carbonyl sulphide in the upper stratosphere (20–50 km).

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Section: Introductionmentioning

confidence: 99%

Electronic excitation of carbonyl sulphide (COS) by high-resolution vacuum ultraviolet photoabsorption and electron-impact spectroscopy in the energy region from 4 to 11 eV

Limão-Vieira

Silva

Almeida

et al. 2015

The Journal of Chemical Physics

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“…Trifluoromethyl sulphur pentafluoride, SF 5 CF 3 , has recently been termed the super greenhouse gas. This claim to fame arises because, per molecule, it makes more contribution to global warming via the greenhouse effect than any other molecule yet detected in the atmosphere.…”

Section: Introductionmentioning

confidence: 99%

“…This claim has since been disputed [3]. Infrared (IR) absorption measurements showed that SF 5 CF 3 has the highest radiative forcing per molecule of any gas found in the atmosphere to date (0.57 W m -2 ppb -1 , a figure since updated to 0.60 ± 0.03 W m -2 ppb -1 [4,5]). Antarctic firn measurements suggested that it has grown from a concentration of near zero in the late 1960s to ca.…”

Section: Introductionmentioning

confidence: 99%

Chapter 3: Trifluoromethyl Sulphur Pentafluoride, SF5CF3: Atmospheric Chemistry and Its Environmental Importance via the Greenhouse Effect

Tuckett

2006

Fluorine and the Environment - Atmospheric Chemistry, Emissions, &Amp; Lithosphere

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Advances in Fluorine Science (2006) 1, chapter 3 (pp. 89-129) (Elsevier, ISBN 0-444-52811-3) Fluorine and the Environment : atmospheric chemistry, emissions and lithosphere DOI: 10.1016/S1872-0358(06) This is the author's version of a work that was accepted for publication in Advances in Fluorine Science.Changes resulting from the publishing process, such as editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. A definitive version was subsequently published in the reference given above. The DOI number of the final paper is also given above. highest per molecule radiative forcing of any greenhouse pollutant, and the value of its global warming potential is only exceeded by that of SF 6 . Using tunable vacuum-UV radiation from a synchrotron and coincidence spectroscopy, the strength of the central S−C bond in SF 5 CF 3 is determined to be 3.86 ± 0.45 eV or 372 ± 43 kJ mol -1 , and this molecule is very unlikely to be removed from the earth's atmosphere by UV photolysis in the stratosphere. Complementary laboratory-based experiments have shown that the main sink route of this greenhouse gas is low-energy electron attachment in the mesosphere, with Lyman-α photodissociation at 121.6 nm being only a minor channel. By comparison with data for SF 6 , the lifetime of SF 5 CF 3 in the earth's atmosphere is estimated to be ca. 1000 years. The principal reason for the current low level of concern about the impact of SF 5 CF 3 on our environment is that the concentration levels are still very low, at the sub parts per trilllion level. The high growth rate of ca. 6% per annum, however, should cause concern for policymakers.

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“…The recent identification of the need for more data on electronic state spectroscopy and subsequent photodissociation and photoionisation pathways leading to chemical reactivity has highlighted the need for more fundamental studies of PA and PE in a wide range of molecules for which such data has not been generated these include biomolecular targets (for radiation chemistry and radiotherapy) [12]; Volatile Organic Species (VOCs) for environmental studies of atmospheric/biosphere interface [13] and a range of compounds used in next generation industries (e.g. replacements for fluorocarbons used in plasma etching) [14,15].…”

Section: Introductionmentioning

confidence: 99%