Forskning ved Københavns Universitet - Københavns Universitet

Forside

Atmospheric chemistry of HFC-152: UV absorption spectrum of CH2FCFHO2 radicals, kinetics of the reaction CH2FCFHO2 + NO → CH2FCHFO + NO2, and fate of the alkoxy radical CH2FCFHO

Publikation: Bidrag til tidsskriftTidsskriftartikel

  • Timothy J. Wallington
  • Michael D. Hurley
  • James C. Ball
  • Thomas Ellermann
  • Nielsen, Ole John
  • Jens Sehested

The ultraviolet absorption spectrum of CH2FCFHO2 radicals and the kinetics and mechanism of their reaction with NO have been studied in the gas phase at 296 K using a pulse radiolysis technique. A long path-length Fourier transform infrared technique was used to study the atmospheric fate of CH2FCFHO radicals. Absorption cross sections were quantified over the wavelength range 220-300 nm. At 240 nm, σCH2FCFHO2 = (3.28 ± 0.40) × 10-18 cm2 molecule-1. Errors are statistical (2 standard deviations) plus our estimate of potential systematic uncertainty (10%). Monitoring the rate of NO2 formation using a monitoring wavelength of 400 nm allowed a lower limit of k3 > 8.7 × 10-12 cm3 molecule-1 s-1 to be derived for the reaction of CH2FCFHO2 radicals with NO. The alkoxy radical CH2FCFHO was found to undergo C-C bond scission rapidly with a rate greater than 6 × 104 s-1. The Cl-atom-initiated oxidation of HFC-152 in air in the presence of NOx gave HC(O)F as the sole carbon-containing product. The carbon balance was 91 ± 10%. Results are discussed with respect to the atmospheric chemistry of HFC-152. As part of the present work, a relative rate technique was used to measure rate constants of (6.7 ± 0.8) × 10-13 and (3.8 ± 1.1) × 10-11 cm3 molecule-1 s-1 for the reaction of CH2FCH2F with Cl and F atoms, respectively.

OriginalsprogEngelsk
TidsskriftJournal of Physical Chemistry
Vol/bind98
Udgave nummer21
Sider (fra-til)5435-5440
Antal sider6
ISSN0022-3654
StatusUdgivet - 1 dec. 1994

ID: 228194190