Cleary Patricia A, Romero Maria Teresa Baeza, Blitz Mark A, Heard Dwayne E, Pilling Michael J, Seakins Paul W, Wang Liming
School of Chemistry, University of Leeds, Leeds, UK.
Phys Chem Chem Phys. 2006 Dec 28;8(48):5633-42. doi: 10.1039/b612127f. Epub 2006 Nov 15.
The pressure and temperature dependence for the reaction of OH + C(2)H(4) was studied over the range of conditions: 200-400 K and 5-600 Torr by laser flash photolysis, laser-induced fluorescence (FP-LIF). Additional experiments were conducted at room temperature by laser flash photolysis, cavity ring-down spectroscopy to facilitate determination of the high pressure limit. One-dimensional master equation calculations were conducted to test the temperature and pressure dependence of the reaction in He and in N(2). The energetics of the reaction and geometries of intermediate species were calculated by ab initio calculations (DFT-BH&HLYP/6-311+G(3df,2p) and CBS-APNO level along DFT-IRC, respectively. An investigation into the importance of a pre-reaction van der Waals complex on the kinetics over the pressure range of the troposphere is discussed. The high pressure rate coefficient was extracted by fitting the master equation calculations to the data and yields k(infinity) = 5.01 x 10(-12) exp(148/T) cm(3) molecule(-1) s(-1). The master equation calculations were then optimized for the pressure fall-off in He and N(2) by varying the average downward energy transfer parameter (DeltaE(down)) for the different collision partners and finally fitted to a Troe expression to determine k(o) and F(cent) for use in atmospheric modeling.
通过激光闪光光解和激光诱导荧光（FP-LIF），在200 - 400 K和5 - 600托的条件范围内研究了OH + C₂H₄反应的压力和温度依赖性。在室温下通过激光闪光光解、腔衰荡光谱进行了额外的实验，以促进高压极限的测定。进行了一维主方程计算，以测试该反应在氦气和氮气中的温度和压力依赖性。分别沿着DFT-IRC通过从头算计算（DFT-BH&HLYP/6-311+G(3df,2p)和CBS-APNO水平）计算了反应的能量学和中间物种的几何结构。讨论了对流层压力范围内预反应范德华络合物对动力学重要性的研究。通过将主方程计算拟合到数据中提取了高压速率系数，得到k(∞) = 5.01 x 10⁻¹² exp(148/T) cm³ molecule⁻¹ s⁻¹。然后通过改变不同碰撞伙伴的平均向下能量转移参数（ΔE(down)）对氦气和氮气中的压力下降进行主方程计算优化，最后拟合到Troe表达式以确定用于大气建模的k₀和F(cent)。
