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Atmospheric chemistry of dimethyl sulfide: UV spectra and self-reaction kinetics of CH3SCH2 and CH3SCH2O2 radicals and kinetics of the reactions CH3SCH2 + O2 → CH3SCH2O2 and CH3SCH2O2 + NO → ...

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Full title: Atmospheric chemistry of dimethyl sulfide: UV spectra and self-reaction kinetics of CH3SCH2 and CH3SCH2O2 radicals and kinetics of the reactions CH3SCH2 + O2 → CH3SCH2O2 and CH3SCH2O2 + NO → CH3SCH2O + NO2. A pulse radiolysis technique has been used to measure the UV spectra of CH3SCH2 and CH3SCH2O2 radicals over the range 225-350 nm. At 285 nm, σ(CH3SCH2) = (9.8 ± 1.7) × 10-8; at 250 nm, σ(CH3SCH2O2) = (4.3 ± 0.7) × 10-18 cm2 molecule-1. Observed self-reaction rate constants, defined as -d[CH3SCH2]/dt = 2k6[CH3SCH2]2 and -d[CH3SCH2O2[/dt = 2k7obs[CH3SCH2O2]2, were k6 = (3.0 ± 0.6) × 10-11 and k7obs = (7.9 ± 1.4) × 10-12 cm3 molecule-1 s-1. Errors are statistical (2 standard deviations) plus our estimate of potential systematic uncertainty (15%). A rate constant, k2 = (5.7 ± 0.4) × 10-12 cm3 molecule-1 s-1, was derived for the addition reaction CH3SCH2 + O2 → CH3SCH2O2. A rate constant, k3 = (1.9 ± 0.6) × 10-11 cm3 molecule-1 s-1, is reported for the reaction of CH3SCH2O2 radicals with NO, producing NO2. Errors for k2 and k3 are 2 standard deviations. Results are discussed with respect to the atmospheric chemistry of dimethyl sulfide.

OriginalsprogEngelsk
TidsskriftJournal of Physical Chemistry
Vol/bind97
Udgave nummer32
Sider (fra-til)8442-8449
Antal sider8
ISSN0022-3654
StatusUdgivet - 1 dec. 1993

ID: 228195927