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Atmospheric chemistry of HFC-272ca: Spectrokinetic investigation of the CH3CF2CH2O2 radical, its reactions with NO and NO2, and the fate of the CH3CF2CH2O radical

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  • Trine E. Møgelberg
  • Nielsen, Ole John
  • Jens Sehested
  • Timothy J. Wallington
  • Michael D. Hurley

A pulse radiolysis technique has been used to investigate the UV absorption spectrum of the CH3CF2CH2O2 radical from HFC-272ca, CH3CF2CH3. The absorption cross sections were quantified in the wavelength range 220-320 nm; at 250 nm the absorption cross section for CH3CF3CH2O2 was σ = (451 ± 59) × 10-20 cm2 molecule-1. By following the increase in NO2 at 400 nm, the rate constant for the reaction of CH3CF2CH2O2 with NO was determined to be (8.5 ± 1.9) × 10-12 cm3 molecule-1 s-1. The reaction of CH3CF2CH2O2 with NO2 was found to have a reaction rate constant of (6.8 ± 0.5) × 10-12 cm3 molecule-1 s-1. The kinetics of the reaction of CH3CF2CH3 with F atoms and CH3CF2CH2 with O2 were studied. The rate constants were (2.8 ± 0.9) × 10-11 and (1.10 ± 0.03) × 10-12 cm3 molecule-1 s-1, respectively. The observed rate constant for the self-reaction of CH3CF2CH2O2 radicals was (8.6 ± 0.4) × 10-12 cm3 molecule-1 s-1. The reaction of CH3CF2CH2O2 radicals with NO gives CH3CF2CH2O radicals; the dominant atmospheric fate of CH3CF2CH2O radicals is reaction with O2 to give CH3CF2CHO. As part of the present work, relative rate techniques were used to measure rate constants at 296 ± 2 K for the reactions of Cl and F atoms with CH3CF2CH3, with the values being (1.7 ± 0.2) × 10-14 and (3.3 ± 0.8) × 10-11 cm3 molecule-1 s-1, respectively.

OriginalsprogEngelsk
TidsskriftJournal of Physical Chemistry
Vol/bind99
Udgave nummer7
Sider (fra-til)1995-2001
Antal sider7
ISSN0022-3654
DOI
StatusUdgivet - 1 jan. 1995

ID: 228191546