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| Titel |
Investigation of the formaldehyde differential absorption cross section at high and low spectral resolution in the simulation chamber SAPHIR |
| VerfasserIn |
T. Brauers, J. Bossmeyer, H.-P. Dorn, E. Schlosser, R. Tillmann, R. Wegener, A. Wahner |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 7, no. 13 ; Nr. 7, no. 13 (2007-07-09), S.3579-3586 |
| Datensatznummer |
250005125
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| Publikation (Nr.) |
 copernicus.org/acp-7-3579-2007.pdf |
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| Zusammenfassung |
| The results from a simulation chamber study on the formaldehyde (HCHO)
absorption cross section in the UV spectral region are presented. We
performed 4 experiments at ambient HCHO concentrations with
simultaneous measurements of two DOAS instruments in the atmosphere
simulation chamber SAPHIR in Jülich. The two instruments differ in
their spectral resolution, one working at 0.2 nm (broad-band,
BB-DOAS), the other at 2.7 pm (high-resolution, HR-DOAS). Both
instruments use dedicated multi reflection cells to achieve long light
path lengths of 960 m and 2240 m, respectively, inside the chamber.
During two experiments HCHO was injected into the clean chamber by
thermolysis of well defined amounts of para-formaldehyde reaching
mixing rations of 30 ppbV at maximum. The HCHO concentration
calculated from the injection and the chamber volume agrees with the
BB-DOAS measured value when the absorption cross section of
Meller and Moortgat (2000) and the temperature coefficient of
Cantrell (1990) were used for data evaluation. In two further
experiments we produced HCHO in-situ from the ozone + ethene
reaction which was intended to provide an independent way of HCHO
calibration through the measurements of ozone and ethene. However, we
found an unexpected deviation from the current understanding of the
ozone + ethene reaction when CO was added to suppress possible
oxidation of ethene by OH radicals. The reaction of the Criegee
intermediate with CO could
be 240 times slower than currently assumed. Based on the BB-DOAS
measurements we could deduce a high-resolution cross section for HCHO
which was not measured directly so far. |
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