The atmospheric chemistry of sulphuryl fluoride, SO₂F₂

T. J. Dillon (1) , A. Horowitz (1) , J. N. Crowley (1)

1 MPIC - Max Planck Institute for Chemistry

The atmospheric chemistry of sulphuryl fluoride, SO₂F₂, was investigated in a series of laboratory studies. A competitive rate method, using pulsed laser photolysis (PLP) to generate O(¹D) coupled to detection of OH by laser induced fluorescence (LIF), was used to determine the overall rate coefficient for the reaction O(¹D) + SO₂F₂ ? products (R1) of k₁ (220?300 K) = (1.3 ± 0.2) × 10^?10 cm³ molecule^?1 s^?1. Monitoring the O(³P) product (R1a) enabled the contribution (?) of the physical quenching process (in which SO₂F₂ is not consumed) to be determined as ? (225?296 K)=(0.55 ± 0.04). Separate, relative rate measurements at 298 K provided a rate coefficient for reactive loss of O(¹D), k_1b, of (5.8 ± 0.8) × 10^?11 cm³ molecule^?1 s^?1 in good agreement with the value calculated from (1??) × k₁=(5.9 ± 1.0) × 10^?11 cm³ molecule^?1 s^?1. Upper limits for the rate coefficients for reaction of SO₂F₂ with OH (R2, using PLP-LIF), and with O₃ (R3, static reactor) were determined as k₂ (294 K)<1 × 10^?15 cm³ molecule^?1 s^?1 and k₃ (294 K)<1 × 10^?23 cm³ molecule^?1 s^?1. In experiments using the wetted-wall flow tube technique, no loss of SO₂F₂ onto aqueous surfaces was observed, allowing an upper limit for the uptake coefficient of ?(pH 2?12)<1 × 10^?7 to be determined. These results indicate that SO₂F₂ has no significant loss processes in the troposphere, and a very long stratospheric lifetime. Integrated band intensities for SO₂F₂ infrared absorption features between 6 and 19 ?m were obtained, and indicate a significant global warming potential for this molecule. In the course of this work, ambient temperature rate coefficients for the reactions O(¹D) with several important atmospheric species were determined. The results (in units of 10^?10 cm³ molecule^?1 s^?1, k_{(O¹D + N2)}=(0.33 ± 0.06); k_{(O¹D + N2O)}=(1.47 ± 0.2) and k_{(O¹D + H2O)}=(1.94 ± 0.5) were in good agreement with other recent determinations.

Domaines: Océan, Atmosphère

T. J. Dillon, A. Horowitz, J. N. Crowley. The atmospheric chemistry of sulphuryl fluoride, SO₂F₂. Atmospheric Chemistry and Physics, 2008, 8 (6), pp.1547-1557. ⟨hal-00296489⟩