Baasandorj Munkhbayar, Marshall Paul, Waterland Robert L, Ravishankara A R, Burkholder James B
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.
J Phys Chem A. 2018 May 17;122(19):4635-4646. doi: 10.1021/acs.jpca.8b02771. Epub 2018 May 4.
Rate coefficients, k, for the gas-phase reaction of the OH radical with ( E)-CFCH═CHCF (( E)-1,1,1,4,4,4-hexafluoro-2-butene, HFO-1336mzz(E)) were measured over a range of temperatures (211-374 K) and bath gas pressures (20-300 Torr; He, N) using a pulsed laser photolysis-laser-induced fluorescence (PLP-LIF) technique. k( T) was independent of pressure over this range of conditions with k(296 K) = (1.31 ± 0.15) × 10 cm molecule s and k( T) = (6.94 ± 0.80) × 10exp[-(496 ± 10)/ T] cm molecule s, where the uncertainties are 2σ, and the pre-exponential term includes estimated systematic error. Rate coefficients for the OD reaction were also determined over a range of temperatures (262-374 K) at 100 Torr (He). The OD rate coefficients were ∼15% greater than the OH values and showed similar temperature dependent behavior with k( T) = (7.52 ± 0.44) × 10exp[-(476 ± 20)/ T] and k(296 K) = (1.53 ± 0.15) × 10 cm molecule s. The rate coefficients for reaction 1 were also measured using a relative rate technique between 296 and 375 K with k(296 K) measured to be (1.22 ± 0.1) × 10 cm molecule s, in agreement with the PLP-LIF results. In addition, the 296 K rate coefficient for the O + ( E)-CFCH═CHCF reaction was determined to be <5.2 × 10 cm molecule s. A theoretical computational analysis is presented to interpret the observed positive temperature dependence for the addition reaction and the significant decrease in OH reactivity compared to the ( Z)-CFCH═CHCF stereoisomer reaction. The estimated atmospheric lifetime of ( E)-CFCH═CHCF, due to loss by reaction with OH, is estimated to be ∼90 days, while the actual lifetime will depend on the location and season of its emission. Infrared absorption spectra of ( E)-CFCH═CHCF were measured and used to estimate the 100 year time horizon global warming potentials (GWP) of 32 (atmospherically well-mixed) and 14 (lifetime-adjusted).
使用脉冲激光光解-激光诱导荧光（PLP-LIF）技术，在一系列温度（211 - 374 K）和浴气压力（20 - 300 Torr；He、N）范围内，测量了OH自由基与（E）-CFCH═CHCF（（E）-1,1,1,4,4,4-六氟-2-丁烯，HFO-1336mzz（E））气相反应的速率系数k。在此条件范围内，k（T）与压力无关，k（296 K） = （1.31 ± 0.15）×10⁻¹⁵ cm³ molecule⁻¹ s⁻¹，k（T） = （6.94 ± 0.80）×10⁻¹² exp[-(496 ± 10)/T] cm³ molecule⁻¹ s⁻¹，其中不确定性为2σ，且指数前因子包括估计的系统误差。还在100 Torr（He）下，在一系列温度（262 - 374 K）范围内测定了OD反应的速率系数。OD速率系数比OH的值大约15%，并且表现出类似的温度依赖性，k（T） = （7.52 ± 0.44）×10⁻¹² exp[-(476 ± 20)/T]，k（296 K） = （1.53 ± 0.15）×10⁻¹⁵ cm³ molecule⁻¹ s⁻¹。反应1的速率系数也使用相对速率技术在296至375 K之间进行了测量，测得k（296 K）为（1.22 ± 0.1）×10⁻¹⁵ cm³ molecule⁻¹ s⁻¹，与PLP-LIF结果一致。此外，确定O + （E）-CFCH═CHCF反应在296 K时的速率系数小于5.2×10⁻¹⁶ cm³ molecule⁻¹ s⁻¹。进行了理论计算分析，以解释观察到的加成反应的正温度依赖性以及与（Z）-CFCH═CHCF立体异构体反应相比OH反应性的显著降低。由于与OH反应而损失，（E）-CFCH═CHCF在大气中的估计寿命约为90天，而实际寿命将取决于其排放的位置和季节。测量了（E）-CFCH═CHCF的红外吸收光谱，并用于估计100年时间跨度的全球变暖潜能值（GWP），对于大气中充分混合的物质为32，对于经寿命调整的物质为14。
