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Atmospheric chemistry of dimethyl carbonate: Reaction with OH radicals, UV spectra of CH3OC(O)OCH2 and CH3OC(O)OCH2O2 radicals, reactions of CH3OC(O)OCH2O2 with NO and NO2, and fate of CH3OC(O)OCH2O radicals

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningfagfællebedømt

  • M. Bilde
  • T. E. Møgelberg
  • J. Sehested
  • Nielsen, Ole John
  • T. J. Wellington
  • M. D. Hurley
  • S. M. Japar
  • M. Dill
  • V. L. Orkin
  • T. J. Buckley
  • R. E. Huie
  • M. J. Kurylo

A flash photolysis-resonance fluorescence technique was used to study the rate constant for the reaction of OH radicals with dimethyl carbonate over the temperature range 252-370 K. The rate constant exhibited a weak temperature dependence, increasing at both low and high temperature from a minimum value of approximately 3.1 × 10-13 cm3 molecule-1 s-1 near room temperature. Pulse radiolysis/transient UV absorption techniques were used to study the ultraviolet absorption spectra and kinetics of CH3OC(O)OCH2 and CH3OC(O)CH2O2 radicals at 296 K. Absorption cross sections of CH3OC(O)OCH2 and CH3OC(O)OCH2O2 at 250 nm were (3.16 ± 0.34) × 10-18 and (3.04 ± 0.43) × 10-18 cm2 molecule-1, respectively. Rate constants measured for the self-reactions of CH3OC(O)OCH2 and CH3OC(O)OCH2O2 radicals and reactions of CH3OC(O)OCH2O2 radicals with NO and NO2 were (5.6 ± 1.1) × 10-11, (1.27 ± 0.21) × 10-11, (1.2 ± 0.2) × 10-11, and (1.2 ± 0.2) × 10-11 cm3 molecule-1 s-1, respectively. The rate constant for reaction of F atoms with dimethyl carbonate was determined by a pulse radiolysis absolute rate technique to be (6.1 ± 0.9) × 10-11 cm3 molecule-1 s-1. A FTIR smog chamber system was used to show that, in 760 Torr of air at 296 K, CH3OC(O)OCH2O radicals are lost via three competing processes: 42 ± 15% via reaction with O2, 14 ± 2% via H atom elimination, and 44 ± 10% via decomposition and/or isomerization. Relative rate techniques were used to measure rate constants for the reactions of F atoms with CH3OC(O)OCH3, (6.4 ± 14) × 10-11 cm3 molecule-1 s-1, and Cl atoms with CH3OC(O)OCH3, CH3OC(O)OCH2Cl, CH3OC(O)OCHO, and HC(O)OC(O)OCHO, (2.3 ± 0.8) × 10-12, (4.6 ± 2.8) × 10-13, (1.7 ± 0.1) × 10-13, and (1.7 ± 0.1) × 10-14 cm3 molecule-1 s-1, respectively. Results are discussed in the context of the atmospheric chemistry of CH3OC(O)OCH3.

OriginalsprogEngelsk
TidsskriftJournal of Physical Chemistry A
Vol/bind101
Udgave nummer19
Sider (fra-til)3514-3525
Antal sider12
ISSN1089-5639
StatusUdgivet - 8 maj 1997

ID: 227487535