guest ::
| Home > Publications database > Studies of Aldehydes in an Atmosphere Simulation Chamber |
| Home > Publications database > Studies of Aldehydes in an Atmosphere Simulation Chamber |
| Dissertation / PhD Thesis/Book | PreJuSER-52278 |
2006
Forschungszentrum Jülich GmbH Zentralbibiothek, Verlag
Jülich
Please use a persistent id in citations: http://hdl.handle.net/2128/496
Report No.: Juel-4218
Abstract: In the course of this thesis, a DOAS instrument using a multiple reflection system of the White design was installed at the atmosphere simulation chamber SAPHIR (Forschungszentrum Jülich, Germany). The DOAS instrument allowed to detect $NO_{3}$ at SAPHIR for the first time. A loss process of $NO_{3}$ was identified in the dry chamber and characterised with a lifetime of (42$\pm$4) min. Apart from that, the chamber was used in three ways. (1) The DOAS could be compared to other detection methods under controlled conditions, which was done for the trace gases $NO_{2}, O_{3}, HONO, H_{2}O$, benzene and m-xylene. The agreement between DOAS and the other methods was very good (13 % maximum deviation in the absolute value, correlation coefficients higher than 0.92). (2) The DOAS could be compared to time profiles of trace gas injections (of benzaldehyde, toluene and HCHO) into the chamber, which were calculated from the sample weight and from fundamental chamber properties. The agreement between the DOAS and the calculations was also good (19 % maximum deviation, R higher than 0.94). Thus, the scaling of the differential absorption cross section of HCHO used in the DOAS evaluations was confirmed. (3) Measurements of the DOAS and other instruments could be used to validate current chemistry models. The OH reactivity in the sunlit chamber was derived from DOAS measurements of benzene and m-xylene and matched a direct OH measurement excellently. Moreover, the HCHO yield from the ethene-ozone reaction was studied. A discrepancy was observed between a model calculation and the measurement, which originated from the model assumptions made for kinetics of reaction intermediates in the ethene-ozone mechanism. Finally, absolute rate studies of the $NO_{3}$ reaction with ethanal (2.6$\pm$0.5), propanal (5.8$\pm$1.0), butanal (11.9$\pm$1.4) and benzaldehyde (2.2$\pm$0.6, all in cm$^{3}s^{-1}$ at 300 K) corroborated the rate coefficients of current literature recommendations at near-ambient concentration levels. However, the measured yields of the product aldehydes in the $NO_{3}$ reactions with propanal and butanal disagreed with model calculations. This discrepancy originated from the model assumptions made for the kinetics of peroxyacyl nitrates in the degradation mechanism of the aldehydes.
|
The record appears in these collections: |
PDF
Fulltext by OpenAccess repository