HR: 1340h
AN: A43A-0875    [Abstracts]
TI: CF3CF=CH2 and CF3CF=CHF: Temperature Dependent OH Rate Coefficients and Global Warming Potentials
AU: * Burkholder, J B
EM: James.B.Burkholder@noaa.gov
AF: Earth System Research Laboratory, 325 Broadway, Boulder, CO 80305,
AU: Papadimitriou, V C
EM: Vassilis.Papadimitriou@noaa.gov
AF: Earth System Research Laboratory, 325 Broadway, Boulder, CO 80305,
AU: Papadimitriou, V C
EM: Vassilis.Papadimitriou@noaa.gov
AF: Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309,
AU: Talukdar, R K
EM: Ranajit.K.Talukdar@noaa.gov
AF: Earth System Research Laboratory, 325 Broadway, Boulder, CO 80305,
AU: Talukdar, R K
EM: Ranajit.K.Talukdar@noaa.gov
AF: Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309,
AU: Portmann, R W
EM: Robert.W.Portmann@noaa.gov
AF: Earth System Research Laboratory, 325 Broadway, Boulder, CO 80305,
AU: Ravishankara, A R
EM: A.R.Ravishankara@noaa.gov
AF: Earth System Research Laboratory, 325 Broadway, Boulder, CO 80305,
AB: Rate coefficients, k(T), over the temperature range 206-380 K are reported for the gas phase reaction of OH radicals with 2,3,3,3-tetrafluoropropene (CF₃CF=CH₂) and 1,2,3,3,3-pentafluoropropene (CF₃CF=CHF), which are major components in proposed substitutes for HFC134a (CF₃CFH₂) in mobile air conditioning units. Rate coefficients were measured under pseudo-first-order conditions in OH using pulsed laser photolysis to produce OH and laser induced fluorescence to detect it. For CF₃CF=CH₂, the rate coefficients are given by the Arrhenius expression k₁(T) = (1.26 ± 0.11) × 10^-12 exp[( 35 ± 10)/T] cm³ molecule^-1 s^-1 where k₁(296 K) = (1.12 ± 0.09) × 10^-12 cm³ molecule^-1 s^-1. For CF₃CF=CHF, the rate coefficients are given by the non-Arrhenius expression k₂(T) = (1.6 ± 0.2) × 10^-18 T² exp[(655 ± 50)/T] cm³ molecule^-1 s^-1 where k₂(296 K) = (1.29 ± 0.06) × 10^-12 cm³ molecule^-1 s^-1. The global warming potentials for CF₃CF=CH₂ and CF₃CF=CHF were calculated to be <4.4 and <3.6, respectively, for the 100 year time horizon using infrared absorption cross sections measured in this work and atmospheric lifetimes of 11.9 and 10.0 days, based solely on OH reactive loss.
DE: 0317 Chemical kinetic and photochemical properties
DE: 0365 Troposphere: composition and chemistry
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting