Reactive and nonreactive quenching of O(1D) by the potent greenhouse gases SO2F2, NF3, and SF5CF3.
A laser flash photolysis-resonance fluorescence technique has been employed to measure rate coefficients and physical vs. reactive quenching branching ratios for O((1)D) deactivation by three potent greenhouse gases, SO(2)F(2)(k(1)), NF(3)(k(2)), and SF(5)CF(3)(k(3)). In excellent agreement with one published study, we find that k(1)(T) = 9.0 x 10(-11) exp(+98/T) cm(3) molecule(-1) s(-1) and that the reactive quenching rate coefficient is k(1b) = (5.8 +/- 2.3) x 10(-11) cm(3) molecule(-1) s(-1) independent of temperature. We find that k(2)(T) = 2.0 x 10(-11) exp(+52/T) cm(3) molecule(-1) s(-1) with reaction proceeding almost entirely (approximately 99%) by reactive quenching. Reactive quenching of O((1)D) by NF(3) is more than a factor of two faster than reported in one published study, a result that will significantly lower the model-derived atmospheric lifetime and global warming potential of NF(3). Deactivation of O((1)D) by SF(5)CF(3) is slow enough (k(3) < 2.0 x 10(-13) cm(3) molecule(-1) s(-1) at 298 K) that reaction with O((1)D) is unimportant as an atmospheric removal mechanism for SF(5)CF(3). The kinetics of O((1)D) reactions with SO(2) (k(4)) and CS(2) (k(5)) have also been investigated at 298 K. We find that k(4) = (2.2 +/- 0.3) x 10(-10) and k(5) = (4.6 +/- 0.6) x 10(-10) cm(3) molecule(-1) s(-1); branching ratios for reactive quenching are 0.76 +/- 0.12 and 0.94 +/- 0.06 for the SO(2) and CS(2) reactions, respectively. All uncertainties reported above are estimates of accuracy (2sigma) and rate coefficients k(i)(T) (i = 1,2) calculated from the above Arrhenius expressions have estimated accuracies of +/- 15% (2sigma).
School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332-0340, USA.
Zhijun
Z
Zhao
Patrick L
PL
Laine
J Michael
JM
Nicovich
Paul H
PH
Wine
D004784:Environmental Monitoring / Q000379:methods*; D005459:Fluorides / Q000737:chemistry*; D057232:Global Warming; D017752:Greenhouse Effect; D006845:Hydrocarbons, Fluorinated / Q000737:chemistry*; D007700:Kinetics; D008027:Light; D008956:Models, Chemical; D017672:Nitrogen Compounds / Q000737:chemistry*; D010126:Ozone / Q000737:chemistry*; D010777:Photochemistry / Q000379:methods; D015203:Reproducibility of Results; D013441:Sulfinic Acids / Q000737:chemistry*; D013457:Sulfur Compounds / Q000737:chemistry*; D013696:Temperature; D013816:Thermodynamics; D013997:Time Factors
D006845:Hydrocarbons, Fluorinated; D017672:Nitrogen Compounds; C516032:SF5CF3; D013441:Sulfinic Acids; D013457:Sulfur Compounds; C534617:nitrogen trifluoride; C048899:sulfuryl fluoride; D010126:Ozone; D005459:Fluorides