title: OH Radical Reaction Rate Coefficients, Infrared Spectrum, and Global Warming Potential of (CF3)2CFCH═CHF (HFO-1438ezy(E)).
abstract: Rate coefficients, k(T), for the OH radical + (E)-(CF3)2CFCH═CHF ((E)-1,3,4,4,4-pentafluoro-3-(trifluoromethyl)-1-butene, HFO-1438ezy(E)) gas-phase reaction were measured using pulsed laser photolysis-laser-induced fluorescence (PLP-LIF) between 214 and 380 K and 50 and 450 Torr (He or N2 bath gas) and with a relative rate method at 296 K between 100 and 400 Torr (synthetic air). Over the range of pressures included in this study, no pressure dependence in k(T) was observed. k(296 K) obtained using the two techniques agreed to within ∼3% with (3.26 ± 0.26) × 10(-13) cm(3) molecule(-1) s(-1) (2σ absolute uncertainty) obtained using the PLP-LIF technique. k(T) displayed non-Arrhenius behavior that is reproduced by (7.34 ± 0.30) × 10(-19)T(2) exp[(481 ± 10)/T) cm(3) molecule(-1) s(-1). With respect to OH reactive loss, the atmospheric lifetime of HFO-1438ezy(E) is estimated to be ∼36 days and HFO-1438ezy(E) is considered a very short-lived substance (VSLS) (the actual lifetime will depend on the time and location of the HFO-1438ezy(E) emission). On the basis of the HFO-1438ezy(E) infrared absorption spectrum measured in this work and its estimated lifetime, a radiative efficiency of 0.306 W m(-2) ppb(-1) (well-mixed gas) was calculated and its 100-year time-horizon global warming potential, GWP100, was estimated to be 8.6. CF3CFO, HC(O)F, and CF2O were identified using infrared spectroscopy as stable end products in the oxidation of HFO-1438ezy(E) in the presence of O2. Two additional fluorinated products were observed and theoretical calculations of the infrared spectra of likely degradation products are presented. The photochemical ozone creation potential of HFO-1438ezy(E) was estimated to be ∼2.15.
authors.affiliation: Earth System Research Laboratory, Chemical Sciences Division, National Oceanic and Atmospheric Administration , 325 Broadway, Boulder, Colorado 80305, United States.|Cooperative Institute for Research in Environmental Sciences, University of Colorado , Boulder, Colorado 80309, United States.|Laboratory of Photochemistry and Chemical Kinetics, Department of Chemistry, University of Crete , Vassilika Vouton, 71003 Heraklion, Crete, Greece.
authors.forename: Vassileios C
authors.initials: VC
authors.lastname: Papadimitriou
authors.affiliation: Earth System Research Laboratory, Chemical Sciences Division, National Oceanic and Atmospheric Administration , 325 Broadway, Boulder, Colorado 80305, United States.
authors.forename: James B
authors.initials: JB
authors.lastname: Burkholder