Atmospheric chemistry of CF₂BrH: Kinetics and mechanism of reaction with F and Cl atoms and fate of CF₂BrO radicals

TY - JOUR

T1 - Atmospheric chemistry of CF2BrH

T2 - Kinetics and mechanism of reaction with F and Cl atoms and fate of CF2BrO radicals

AU - Bilde, Merete

AU - Sehested, Jens

AU - Møgelberg, Trine E.

AU - Wallington, Timothy J.

AU - Nielsen, Ole J.

PY - 1996/4/25

Y1 - 1996/4/25

N2 - A pulse radiolysis technique was used to investigate the kinetics and products of the reaction of CF2BrH with fluorine atoms at 296 K. This reaction forms an adduct which is in dynamic equilibrium with CF2BrH and fluorine atoms. The UV absorption spectrum of the adduct was measured relative to the UV spectrum of the CH3O2 radical over the range 230-380 nm. At 280 nm, an absorption cross section of (1.3 ± 0.3) × 10-17 cm2 molecule-1 was determined. From the absorption at 280 nm the equilibrium constant K5 = [adduct]/ ([F][CF2BrH]) was measured to be (1.59 ± 0.13) × 10-17 cm3 molecule-1. In 1 atm of SF6, the forward rate constant k5 = (1.4 ± 0.5) × 10-11 cm3 molecule-1 s-1 and the backward rate constant k-5 = (8.8 ± 3.0) × 105 s-1 were determined by monitoring the rate of formation and loss of the adduct. As part of the present work a relative rate technique was used to measure k(Cl+CF2BrH) = (5.8 ± 1.0) × 10-15 cm3 molecule-1 s-1 at 296 K and 700 Torr of N2. The fate of the oxy radical, CF2BrO, in the atmosphere is bromine atom elimination and formation of COF2.

AB - A pulse radiolysis technique was used to investigate the kinetics and products of the reaction of CF2BrH with fluorine atoms at 296 K. This reaction forms an adduct which is in dynamic equilibrium with CF2BrH and fluorine atoms. The UV absorption spectrum of the adduct was measured relative to the UV spectrum of the CH3O2 radical over the range 230-380 nm. At 280 nm, an absorption cross section of (1.3 ± 0.3) × 10-17 cm2 molecule-1 was determined. From the absorption at 280 nm the equilibrium constant K5 = [adduct]/ ([F][CF2BrH]) was measured to be (1.59 ± 0.13) × 10-17 cm3 molecule-1. In 1 atm of SF6, the forward rate constant k5 = (1.4 ± 0.5) × 10-11 cm3 molecule-1 s-1 and the backward rate constant k-5 = (8.8 ± 3.0) × 105 s-1 were determined by monitoring the rate of formation and loss of the adduct. As part of the present work a relative rate technique was used to measure k(Cl+CF2BrH) = (5.8 ± 1.0) × 10-15 cm3 molecule-1 s-1 at 296 K and 700 Torr of N2. The fate of the oxy radical, CF2BrO, in the atmosphere is bromine atom elimination and formation of COF2.

UR - http://www.scopus.com/inward/record.url?scp=0010801838&partnerID=8YFLogxK

M3 - Journal article

AN - SCOPUS:0010801838

SN - 0022-3654

VL - 100

SP - 7050

EP - 7059

JO - Journal of Physical Chemistry

JF - Journal of Physical Chemistry

IS - 17

ER -