OH + NO + M → HONO + M反应的双分子速率系数与压力、温度和水蒸气的关系
Pressure, Temperature, and Water Vapor Dependencies of the Bimolecular Rate Coefficients for the Reaction OH + NO + M → HONO + M.
作者信息
Woods Megan, Winiberg Frank A F, Markus Charles R, Zuraski Kristen, Shannon Robin, Khan M Anwar H, Shallcross Dudley E, Sander Stanley P, Okumura Mitchio, McPherson Michael, Smith Sonya, Percival Carl J
机构信息
Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States.
NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109, United States.
出版信息
J Phys Chem A. 2025 Jun 26;129(25):5579-5592. doi: 10.1021/acs.jpca.5c00331. Epub 2025 Jun 11.
OH+NO is an important termolecular association reaction in the troposphere and stratosphere that influences the atmospheric ozone budget. In this study, rate coefficients for the reaction of OH + NO + HONO + were measured under conditions relevant to the troposphere/lower stratosphere over a temperature range of 228-298 K and pressure range of 50-750 Torr using N as a bath gas. Time-resolved kinetics were studied by pulsed laser photolysis-laser-induced fluorescence (PLP-LIF) detecting OH by laser-induced fluorescence. Data for the temperature range 258-298 K were fit to two falloff expressions, with the JPL expressions ( = 7.37 × 10(/300 K) cm molecule s and = 3.44 × 10(/300 K)cm molecule s) and IUPAC expression ( = 6.80 × 10(/300 K) cm molecule s, = 0.81, = 1.96 × 10(/300 K) cm molecule s). At temperatures < 258 K, the measured rate coefficients were significantly higher than the IUPAC and JPL fits. To accommodate the rate coefficient deviation from the two expressions, data across the entire temperature range (228-298 K) was fit with two approaches. First, rate coefficients were fit with an empirical modification by adding a second falloff term to the JPL expression with a second low-pressure rate coefficient of = 5.20 × 10(/300 K) cm molecule s. Second, , , and were fit globally to the entire temperature data set, but F was varied for each individual temperature, which increased with decreasing temperature. In the second portion of the study, the influence of HO on the reaction rate was investigated using a N-HO mixture as the bath gas at 50 Torr and 273 and 298 K. The JPL and IUPAC falloff expressions were modified to include HO as a third-body collisional partner consistent with a nonlinear mixture model. Fits to the data yielded the low pressure termolecular rate coefficients in HO, = 3.81 × 10(/300 K) and = 3.31 × 10(/300 K) cm molecule s, respectively. Experimental data were fit using MESMER give energy relaxation parameters of <Δ> = 170 ± 10 cm and <Δ> = 634 ± 20 cm, indicating that HO is a 4× more efficient collisional quencher than N alone. The modified JPL expressions with the newly derived low pressure rate coefficients were implemented into a STOCHEM-CRI atmospheric model. Predictions of HONO concentrations with the new rates were up to 15% higher in remote tropical regions.
OH + NO是对流层和平流层中一个重要的三分子缔合反应，它会影响大气中的臭氧收支。在本研究中，使用氮气作为缓冲气体，在与对流层/平流层下部相关的条件下，于228 - 298 K的温度范围和50 - 750 Torr的压力范围内，测量了OH + NO反应生成HONO的速率系数。通过脉冲激光光解 - 激光诱导荧光（PLP - LIF）技术研究时间分辨动力学，利用激光诱导荧光检测OH。258 - 298 K温度范围内的数据拟合为两个衰减表达式，分别采用JPL表达式（(k_0 = 7.37×10^{−12}(T/300 K)^{−2.58}) (cm^3) molecule(^{−1}) (s^{−1}) 和 (k_{\infty}=3.44×10^{−11}(T/300 K)^{−1.64}) (cm^3) molecule(^{−1}) (s^{−1})）和IUPAC表达式（(k_0 = 6.80×10^{−12}(T/300 K)^{−2.62}) (cm^3) molecule(^{−1}) (s^{−1})，(n = 0.81)，(k_{\infty}=1.96×10^{−11}(T/300 K)^{−1.52}) (cm^3) molecule(^{−1}) (s^{−1})）。在温度低于258 K时，测量得到的速率系数显著高于IUPAC和JPL的拟合值。为了适应与这两个表达式的速率系数偏差，对整个温度范围（228 - 298 K）的数据采用了两种方法进行拟合。首先，通过在JPL表达式中添加第二个衰减项，其低压速率系数为(k_0 = 5.20×10^{−12}(T/300 K)^{−2.58}) (cm^3) molecule(^{−1}) (s^{−1})，对速率系数进行经验修正。其次，对(k_0)、(k_{\infty})和(n)进行全局拟合整个温度数据集，但针对每个单独温度改变(F)值，(F)值随温度降低而增加。在研究的第二部分，在50 Torr以及273 K和298 K的条件下，使用N - HO混合物作为缓冲气体，研究了HO对反应速率的影响。对JPL和IUPAC衰减表达式进行修正，将HO作为第三体碰撞伙伴，符合非线性混合模型。对数据的拟合得到HO中的低压三分子速率系数，分别为(k_0 = 3.81×10^{−12}(T/300 K)^{−2.58}) 和 (k_{\infty}=3.31×10^{−11}(T/300 K)^{−1.64}) (cm^3) molecule(^{−1}) (s^{−1})。使用MESMER拟合实验数据得到能量弛豫参数(<ΔE_{rot}>=170 ± 10 cm^{−1}) 和 (<ΔE_{vib}>=634 ± 20 cm^{−1})，表明HO作为碰撞猝灭剂比单独的N效率高4倍。将新推导的低压速率系数的修正JPL表达式应用于STOCHEM - CRI大气模型。在偏远热带地区，用新速率预测的HONO浓度高出多达15%。
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