Publication Date:
2016-05-03
Description:
The chemical stability of levoglucosan was studied by exploring its isotopic fractionation during the oxidation by hydroxyl radicals. Aqueous solutions as well as mixed (NH 4 ) 2 SO 4 − levoglucosan particles were exposed to OH. In both cases, samples experiencing different extents of processing were isotopically analyzed by Thermal Desorption - Gas Chromatography - Isotope Ratio Mass Spectrometry (TD-GC-IRMS). From the dependence of levoglucosan δ 13 C and concentration on the reaction extent, the kinetic isotope effect (KIE) of the OH oxidation reactions was determined to be 1.00187±0.00027 and 1.00229±0.00018, respectively. Both show good agreement within the uncertainty range. For the heterogeneous oxidation of particulate levoglucosan by gas-phase OH, a reaction rate constant of (2.67±0.03)·10 −12 molec cm −3 s −1 was derived. The laboratory kinetic data, together with isotopic source and ambient observations give information on the extent of aerosol chemical processing in the atmosphere.
Print ISSN:
0094-8276
Electronic ISSN:
1944-8007
Topics:
Geosciences
,
Physics
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