HR: 0800h
AN: A21E-0792    [Abstracts]
TI: Kinetics of HO₂ reactions in the upper troposphere and lower stratosphere
AU: * Ploeger, J M
EM: ploeger@aerodyne.com
AF: Aerodyne Research, Inc., 45 Manning Road, Billerica, MA 01821, United States
AU: Herndon, S C
AF: Aerodyne Research, Inc., 45 Manning Road, Billerica, MA 01821, United States
AU: Zahniser, M S
AF: Aerodyne Research, Inc., 45 Manning Road, Billerica, MA 01821, United States
AU: Kolb, C E
AF: Aerodyne Research, Inc., 45 Manning Road, Billerica, MA 01821, United States
AB: Reaction kinetics of HO₂ complexes with small organic molecules are investigated at conditions relevant to the upper troposphere and lower stratosphere (UTLS). At the lower temperatures associated with higher altitudes, these HO₂ adduct species can play a significant role in kinetic mechanisms. Using a turbulent flow tube reactor capable of operating at temperatures as low as 200 K and pressures ranging from 60 to 200 Torr we have been able to improve the understanding of HO₂ kinetics in the UTLS. An elementary reaction rate mechanism for HO_x and single carbon species has been constructed to both guide experiments and interpret the results. Previous ab initio studies have determined that there is a potentially significant pathway from the reaction of the HO₂•H₂O adduct with HO₂ to form O₃ and 2 H₂O. An upper bound on this proposed ozone branching ratio has been measured at conditions relevant to the UTLS. The reaction network of HO₂ + HCHO has been explored as well and the rate of HCOOH formation has been measured at a range of temperatures and pressures.
DE: 0317 Chemical kinetic and photochemical properties
DE: 0365 Troposphere: composition and chemistry
DE: 0394 Instruments and techniques
DE: 3934 Optical, infrared, and Raman spectroscopy
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting