（E）-和（Z）-CFCF═CFCF与OH自由基和Cl原子气相反应的速率系数
Rate Coefficients for the Gas-Phase Reaction of ( E)- and ( Z)-CFCF═CFCF with the OH Radical and Cl-Atom.
作者信息
Baasandorj Munkhbayar, Papadimitriou Vassileios C, Burkholder James B
机构信息
Earth System Research Laboratory, Chemical Sciences Division , National Oceanic and Atmospheric Administration , 325 Broadway , Boulder , Colorado 80305-3328 , United States.
Cooperative Institute for Research in Environmental Sciences , University of Colorado , Boulder , Colorado 80309 , United States.
出版信息
J Phys Chem A. 2019 Jun 20;123(24):5051-5060. doi: 10.1021/acs.jpca.9b03095. Epub 2019 Jun 6.
The rate coefficients, k, for the gas-phase reaction of the OH radical and Cl-atom with ( E)- and ( Z)-CFCF═CFCF were measured using a relative rate technique over a range of temperature (240-375 K) and bath gas pressure (50-630 Torr, He). The obtained rate coefficients were found to be independent of pressure under these conditions. The obtained rate coefficients for the reaction of Cl-atom with ( E)- and ( Z)-CFCF═CFCF at 296 K were k(296 K) = (7.23 ± 0.3) × 10 cm molecule s and k(296 K) = (6.70 ± 0.3) × 10 cm molecule s, respectively, with the temperature dependence described by the Arrhenius expressions: k( T) = (3.47 ± 0.35) × 10 exp[(210 ± 25)/ T] cm molecule s and k( T) = (3.37 ± 0.35) × 10 exp[(199 ± 25)/ T] cm molecule s. The rate coefficients for the OH radical reaction with ( E)- and ( Z)-CFCF═CFCF were found to be k(296-375 K) = (4.34 ± 0.45) × 10 cm molecule s and k(296-375 K) = (3.30 ± 0.35) × 10 cm molecule s, respectively. The quoted rate coefficient uncertainties are 2σ (95% confidence level) and include estimated systematic errors. The rate coefficients for the reaction of OH with a mixture of the two stereoisomers were determined using a pulsed laser photolysis-laser-induced fluorescence (PLP-LIF) technique for comparison with previous kinetic measurements using stereoisomer mixtures. The effective rate coefficient for the 0.7/0.3 ( E)/( Z) stereoisomer sample was found to be nearly independent of temperature over the range 222-375 K with a value of (4.47 ± 0.36) × 10 cm molecule s. The atmospheric lifetimes for ( E)- and ( Z)-CFCF═CFCF due to OH-reactive loss are estimated to be 25 and 35 days, respectively. The lifetime-corrected radiative efficiencies (W m ppb) and 100 year time horizon global warming potentials derived in this work are 0.05 and 1.2 for ( E)-CFCF═CFCF and 0.13 and 4.1 for ( Z)-CFCF═CFCF. The photochemical ozone creation potentials for ( E)- and ( Z)-CFCF═CFCF are estimated to be 2.5 and 2.1, respectively.
采用相对速率技术，在一系列温度（240 - 375 K）和浴气压力（50 - 630 Torr，氦气）条件下，测量了OH自由基和Cl原子与（E）-和（Z）-CFCF═CFCF在气相反应中的速率系数k。发现在这些条件下，所获得的速率系数与压力无关。在296 K时，Cl原子与（E）-和（Z）-CFCF═CFCF反应的速率系数分别为k(296 K) = (7.23 ± 0.3) × 10⁻¹⁴ cm³ molecule⁻¹ s⁻¹和k(296 K) = (6.70 ± 0.3) × 10⁻¹⁴ cm³ molecule⁻¹ s⁻¹，其温度依赖性由阿伦尼乌斯表达式描述：k(T) = (3.47 ± 0.35) × 10⁻¹⁴ exp[(210 ± 25)/T] cm³ molecule⁻¹ s⁻¹和k(T) = (3.37 ± 0.35) × 10⁻¹⁴ exp[(199 ± 25)/T] cm³ molecule⁻¹ s⁻¹。OH自由基与（E）-和（Z）-CFCF═CFCF反应的速率系数分别为k(296 - 375 K) = (4.34 ± 0.45) × 10⁻¹⁴ cm³ molecule⁻¹ s⁻¹和k(296 - 375 K) = (3.30 ± 0.35) × 10⁻¹⁴ cm³ molecule⁻¹ s⁻¹。所引用的速率系数不确定度为2σ（95%置信水平），并包括估计的系统误差。使用脉冲激光光解 - 激光诱导荧光（PLP - LIF）技术测定了OH与两种立体异构体混合物反应的速率系数，以便与之前使用立体异构体混合物进行的动力学测量进行比较。对于0.7/0.3（E）/（Z）立体异构体样品，有效速率系数在222 - 375 K范围内几乎与温度无关，其值为(4.47 ± 0.36) × 10⁻¹⁴ cm³ molecule⁻¹ s⁻¹。由于与OH反应而导致的（E）-和（Z）-CFCF═CFCF在大气中的寿命估计分别为25天和35天。在本工作中得出的寿命校正辐射效率（W m⁻² ppb⁻¹）和100年时间跨度的全球变暖潜能值，对于（E）-CFCF═CFCF分别为0.05和1.2，对于（Z）-CFCF═CFCF分别为0.13和4.1。（E）-和（Z）-CFCF═CFCF的光化学臭氧生成潜能估计分别为2.5和2.1。
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