KINETICS MEASUREMENTS OF HO$_2$ AND RO$_2$ SELF AND CROSS REACTIONS USING INFRARED KINETIC SPECTROSCOPY (IRKS)
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Date
2007
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Publisher
Ohio State University
Abstract
Reactions between RO$_2$ and HO$_2$ are important in the gas phase oxidation of volatile organics in the atmosphere. The rate constants for the reactions of HO$_2$ + C$_2$H$_5$O$_2$, and C$_2$H$_5$O$_2$ + C$_2$H$_5$O$_2$ were measured using a novel approach to radical radical reactions that employs two independent spectroscopic probes. HO$_2$ was monitored at 6638.2 cm$^{-1}$ using near-IR diode laser WM spectroscopy, and C$_2$H$_5$O$_2$ was monitored at 250 nm using UV absorption. Experiments were run under conditions relevant to the upper troposphere (221-298 K and 50-400 Torr). Measurements of the rate constants for both reactions as well as a measurement of the branching fraction leading to the alkoxy channel of the C$_2$H$_5$O$_2$ self reaction will be discussed. Preliminary results are: k$_{HC}$ = $(6.4\pm1.4)\times10^{-13}$ cm$^{3}$ molec$^{-1}$ s$^{-1}$ Exp(($601\pm120$)/ T ), k$_{CC}$ = $(1.10\pm0.20)\times 10^{-13}$ cm$^{3}$ molec$^{-1}$ s$^{-1}$ independent of temperature, and a branching fraction of $0.32\pm0.13$.
Description
Author Institution: Department of Chemistry, California Institute of Technology, Pasadena, CA 91125; Jet Propulsion Laboratory, Pasadena, CA 91109