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Ultraviolet absorption spectra and kinetics of the self-reaction of CH2Br and CH2BrO2 radicals in the gas phase at 298 K

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The ultraviolet absorption spectra of CH2Br and CH2BrO2 radicals and the kinetics of their self-reactions have been studied in the gas phase at 298 K by using the pulse radiolysis technique. Absorption cross sections were quantified over the wavelength range 220-350 nm. Measured cross sections near the absorption maxima were σCH2Br(280 nm) = (6.26 ± 1.15) × 10-18 cm2 molecule-1 and σCH2BrO2(250 nm) = (7.20 ± 0.83) × 10-18 cm2 molecule-1. Errors represent statistical errors (2σ) together with our estimate of potential systematic errors (10%). The absorption cross-sectional data were then used to derive the observed self-reaction rate constants for reactions 1 and 2, defined as -d[R]/dt = 2koba[R]2 (R = CH2Br or CH2BrO2) of CH2Br + CH2Br → products (1) CH2BrO2 + CH2BrO2 → products (2) k1 = (2.93 ± 0.60) × 10-11 cm3 molecule-1 s-1 and k2obs = (3.26 ± 0.31) × 10-11 cm3 molecule-1 s-1 (quoted errors represent 2σ). These results are discussed with respect to previous studies of the absorption spectra and kinetics of peroxy radicals.

OriginalsprogEngelsk
TidsskriftJournal of Physical Chemistry
Vol/bind95
Udgave nummer22
Sider (fra-til)8714-8719
Antal sider6
ISSN0022-3654
StatusUdgivet - 1 dec. 1991

ID: 228197762