Kinetics and mechanism of the reaction of F atoms with CH3Br
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Kinetics and mechanism of the reaction of F atoms with CH3Br. / Sehested, Jens; Bilde, Merete; Møgelberg, Trine; Wellington, Timothy J.; Nielsen, Ole John.
I: Journal of Physical Chemistry, Bind 100, Nr. 26, 27.06.1996, s. 10989-10998.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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T1 - Kinetics and mechanism of the reaction of F atoms with CH3Br
AU - Sehested, Jens
AU - Bilde, Merete
AU - Møgelberg, Trine
AU - Wellington, Timothy J.
AU - Nielsen, Ole John
PY - 1996/6/27
Y1 - 1996/6/27
N2 - The reaction of F atoms with CH3Br at 296 K was studied using a pulse radiolysis/transient UV absorption spectroscopy absolute technique and a FTIR relative rate technique. The rate constant for this reaction was determined to be (4.46 ± 0.22) × 10-11. The reaction proceeds via two channels, 69 ± 5%, via hydrogen abstraction giving CH2Br radicals and HF, and 31 ± 5%, to give the adduct CH3Br-F. In the FTIR system the observed rate constant was 69 ± 8% of that measured using the pulse radiolysis system because the CH3Br-F adduct falls apart to re-form the reactants. The CH3Br-F adduct reacts with NO, with a rate constant of (2.25 ± 0.14) × 10-11 cm3 molecule-1 s-1, giving FNO as a product. There was no discernible reaction of the CH3Br-F adduct with O2 and an upper limit of 6 × 10-15 cm3 molecule-1 s-1 was derived for this reaction. The CH3Br-F adduct absorbs strongly at 260-340 nm. The absorption cross section at 280 nm of the CH3Br-F adduct was (2.06 ± 0.31) × 10-17 cm2 molecule-1. A lower limit for the equilibrium constant was [CH3Br-F]/([CH3Br][F]) > 5 × 10-16 cm3 molecule-1 at 296 K. A lower limit of 12 kcal mol-1 is estimated for the binding energy of the F atom in the CH3Br-F adduct. The UV absorption spectrum of the CH2BrO2 radical was determined; at 250 nm σ = (3.4 ± 0.9) × 10-18 cm2 molecule-1.
AB - The reaction of F atoms with CH3Br at 296 K was studied using a pulse radiolysis/transient UV absorption spectroscopy absolute technique and a FTIR relative rate technique. The rate constant for this reaction was determined to be (4.46 ± 0.22) × 10-11. The reaction proceeds via two channels, 69 ± 5%, via hydrogen abstraction giving CH2Br radicals and HF, and 31 ± 5%, to give the adduct CH3Br-F. In the FTIR system the observed rate constant was 69 ± 8% of that measured using the pulse radiolysis system because the CH3Br-F adduct falls apart to re-form the reactants. The CH3Br-F adduct reacts with NO, with a rate constant of (2.25 ± 0.14) × 10-11 cm3 molecule-1 s-1, giving FNO as a product. There was no discernible reaction of the CH3Br-F adduct with O2 and an upper limit of 6 × 10-15 cm3 molecule-1 s-1 was derived for this reaction. The CH3Br-F adduct absorbs strongly at 260-340 nm. The absorption cross section at 280 nm of the CH3Br-F adduct was (2.06 ± 0.31) × 10-17 cm2 molecule-1. A lower limit for the equilibrium constant was [CH3Br-F]/([CH3Br][F]) > 5 × 10-16 cm3 molecule-1 at 296 K. A lower limit of 12 kcal mol-1 is estimated for the binding energy of the F atom in the CH3Br-F adduct. The UV absorption spectrum of the CH2BrO2 radical was determined; at 250 nm σ = (3.4 ± 0.9) × 10-18 cm2 molecule-1.
UR - http://www.scopus.com/inward/record.url?scp=0001589264&partnerID=8YFLogxK
M3 - Journal article
AN - SCOPUS:0001589264
VL - 100
SP - 10989
EP - 10998
JO - Journal of Physical Chemistry
JF - Journal of Physical Chemistry
SN - 0022-3654
IS - 26
ER -
ID: 225753535