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| Titel |
A new method for speciated CH3O2 radical detection and HIRAC (Highly Instrumented Reactor for Atmospheric Chemistry) studies of the CH3O2 self-reaction |
| VerfasserIn |
Lavinia Onel, Alexander Brennan, Paul W. Seakins, Lisa Whalley, Dwayne Heard |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250128762
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| Publikation (Nr.) |
 EGU/EGU2016-8788.pdf |
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| Zusammenfassung |
| A new method has been developed for the speciated detection of CH3O2 radicals by
FAGE (Fluorescence Assay by Gas Expansion) by titrating CH3O2 to CH3O by
reaction with added NO and then detecting the resultant CH3O by LIF (laser induced
fluorescence). The limit of detection of the technique is ∼108 cm−3 CH3O2 for a unity
signal-to-noise ratio and 5 min averaging time. The method has been used for time
monitoring of CH3O2 during its self-reaction within HIRAC at 1 bar and room
temperature to determine a preliminary value of the rate coefficient of 4.2 × 10−13
cm3 s−1, which lies in the range of the previous results, (2.7 – 5.2) × 10−13 cm3
s−1.1
In addition to detection of CH3O2, products of the CH3O2 self-reaction were also
observed for the two reaction channels over a range of temperatures from 260 – 320
K:
(a) 2CH3O2 → CH2O + CH3OH; (b) 2CH3O2 → 2CH3O + O2,
namely HO2 radicals (from reaction of CH3O + O2) and formaldehyde monitored by
FAGE and formaldehyde and methanol observed by FTIR. A good agreement has been
obtained between the FTIR and FAGE measurements of CH2O which increased to ∼ 2 ppmv
over the experiments. Using the concentrations of CH3OH and CH2O, the branching ratio for
channel (a) at room temperature has been determined as ra = 0.66 ± 0.06. The result is in
very good agreement with the value recommended in the review of Tyndall et al.2 of ra =
0.63 ± 0.06. No temperature dependence of ra has been observed from 296 K to 321
K.
1. http://iupac.pole-ether.fr/
2. G. S. Tyndall et al., J. Geophys. Res. 106, 12157 (2001). |
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