HR: 0830h
AN: A11F-0045    [PDF]
TI: Product Analysis of the OH Oxidation of Acetic Acid in Air in the Presence of NO
AU: * Dransfield, T J
EM: dransf@post.harvard.edu
AF: Harvard University. Department of Chemistry and Chemical Biology, 12 Oxford Street, Cambridge, MA 02138 United States
AU: Sprengnether, M M
EM: spreng@huarp.harvard.edu
AF: State University of New York at Albany, Atmospheric Sciences Research Center, Albany, NY 12203 United States
AU: Donahue, N M
EM: nmd+@cmu.edu
AF: Carnegie Mellon University, Departments of Chemistry and Chemical Engineering, 1106 Doherty Hall, Pittsburgh, PA 15213 United States
AU: Demerjian, K L
EM: kld@atmos.albany.edu
AF: State University of New York at Albany, Atmospheric Sciences Research Center, Albany, NY 12203 United States
AU: Anderson, J G
EM: anderson@chemistry.harvard.edu
AF: Harvard University. Department of Chemistry and Chemical Biology, 12 Oxford Street, Cambridge, MA 02138 United States
AB: The oxidation of acetic acid ({CH$_3$COOH}) by {OH} in air and in the presence of high {NO} was studied under ``wall-less" conditions in Harvard's High Pressure Flow System. The experiments were conducted at 50 torr with a reaction time on the order of a second. In the present work, first stage products are formed at 10$^{12}$ molecules/cm$^3$ levels and analyzed in-situ by {FTIR} spectroscopy. The use of Reaction Modulation Spectroscopy allows for determination of product concentrations and for accurate measurement of the very small ($<$1% and $<$3%, respectively) change in acid and NO reactants. Observed products from the reaction include nitrogen dioxide (NO$_2$) and near unit yield of carbon dioxide (CO$_2$), supporting the proposed mechanism of attack on the acidic hydrogen followed by dissociation. The expected co-product formaldehyde (CH2O) is not observed, but the anticipated concentrations are below the detection limit in the current experiment. We observe no evidence of formation of carbon monoxide (CO), placing an upper limit on its yield at $<$1%, indicating that attack of the methyl hydrogens is either insignificant or does not form CO as has been previously proposed. The observed primary products and proposed mechanism have long been suggested, but this is the first direct observation of the near unit CO$_2$ yield of the reaction under high NO$_x$ conditions.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0345 Pollution--urban and regional (0305)
DE: 0365 Troposphere--composition and chemistry
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting