Journal Article

PreJuSER-12234

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Isotope effect in the formation of H2 from H2CO studied at the atmospheric simulation chamber SAPHIR

Röckmann, T. ; Walter, S. ; Bohn, B.FZJ* ; Spahn, H.FZJ* ; Brauers, T.FZJ* ; Tillmann, R.FZJ* ; Schlosser, E.FZJ* ; Koppmann, R. ; Rohrer, F.FZJ*

2010
EGU Katlenburg-Lindau

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Please use a persistent id in citations: http://hdl.handle.net/2128/10051  doi:10.5194/acp-10-5343-2010

Abstract: Formaldehyde of known, near-natural isotopic composition was photolyzed in the SAPHIR atmosphere simulation chamber under ambient conditions. The isotopic composition of the product H-2 was used to determine the isotope effects in formaldehyde photolysis. The experiments are sensitive to the molecular photolysis channel, and the radical channel has only an indirect effect and cannot be effectively constrained. The molecular channel kinetic isotope effect KIEmol, the ratio of photolysis frequencies j(HCHO -> CO+H-2)/j(HCDO -> CO+HD) at surface pressure, is determined to be KIEmol = 1.63(-0.046)(+0.038) . This is similar to the kinetic isotope effect for the total removal of HCHO from a recent relative rate experiment (KIEtot= 1.58 +/- 0.03), which indicates that the KIEs in the molecular and radical photolysis channels at surface pressure (approximate to 100 kPa) may not be as different as described previously in the literature.

Keyword(s): J

Note: We thank Cornelia Richter for initial model studies to determine the most suitable conditions in the SAPHIR chamber. This work was funded by the Dutch science foundation NWO, project 816.01.001, H<INF>2</INF> budget.

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Research Program(s):

1. Atmosphäre und Klima (P22)

Appears in the scientific report 2010

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