The atmospheric chemistry of sulphuryl fluoride, SO2F2

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(D-1) coupled to detection of OH by laser induced fluorescence (LIF), was used to determine the overall rate coefficient for the reaction O(D-1)+ SO2F2 -> products (R1) of k(1) (220-300 K) = (1.3 +/- 0.2) x 10(-10) cm(3) molecule(-1) s(-1). Monitoring the O(P-3) product (R1a) enabled the contribution (alpha) of the physical quenching process (in which SO2F2 is not consumed) to be determined as alpha (225-296 K)=(0.55 +/- 0.04). Separate, relative rate measurements at 298K provided a rate coefficient for reactive loss of O(D-1), k(1b), of (5.8 +/- 0.8) x 10(-11) cm(3) molecule(-1) s(-1) in good agreement with the value calculated from (1-alpha) x k(1)=(5.9 +/- 1.0) x 10(-11) cm(3) molecule(-1) s(-1). Upper limits for the rate coefficients for reaction of SO2F2 with OH (R2, using PLP-LIF), and with O-3 (R3, static reactor) were determined as k(2) (294 K) < 1 x 10(-15) cm(3) molecule(-1) s(-1) and k(3) (294 K)< 1 x 10(-23) cm(3) 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 gamma(pH 2-12)< 1 x 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 mu 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(D-1) with several important atmospheric species were determined. The results (in units of 10(-10) cm(3) molecule(-1) s(-1)), k((OD)-D-1+ N-2)=(0.33 +/- 0.06); k((OD)-D-1+ N2O)=(1.47 +/- 0.2) and k((OD)-D-1+H2O)=(1.94 +/- 0.5) were in good agreement with other recent determinations.