Kinetics of CH2OO reactions with SO2, NO2, NO, H2O and CH3CHO as a function of pressure
Kinetics of CH2OO reactions with SO2, NO2, NO, H2O and CH3CHO as a function of pressure
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DOI：
10.1039/c3cp54391a
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发表时间：
2014-01-01
影响因子：
3.3
通讯作者：
Seakins, Paul
中科院分区：
文献类型：
--
作者：
Stone, Daniel;Blitz, Mark;Seakins, Paul
报道了295K下CH2OO与SO2、NO2、NO、H2O和CH3CHO的Criegee中间体反应以及CH2I与NO2的反应动力学。在准一级条件下测量了CH2I2-O-2-N-2混合气体在过量助试剂存在下的闪光光解，并用激光诱导荧光(LIF)光谱监测了CHHO的反应产物，对于与SO2的反应，用光电离质谱仪(PIMS)直接检测了CH2OO。CH2OO+SO2和CH2OO+NO2的速率系数在所研究的范围内与压力无关，分别为(3.42+/-0.42)×10(-11)cm(3)S(-1)(测量在1.5Torr到450Torr之间)和(1.5+/-0.5x10(-12)cm(3)S(-1)(测量在25Torr到300Torr之间)。CH2OO+CH3CHO的反应速率系数与压力有关，甲醛的产率随压力的增加而降低。CH2OO+NO和CH2OO+H2O的速率系数上限分别为2×10(-13)cm(3)S(-1)和9×10(-17)cm(3)S(-1)。CH2OO+H2O的速率系数的上限明显低于以前报告的水平，这将影响对CH2OO化学的大气影响的模拟。
Kinetics of CH2OO Criegee intermediate reactions with SO2, NO2, NO, H2O and CH3CHO and CH2I radical reactions with NO2 are reported as a function of pressure at 295 K. Measurements were made under pseudo-first-order conditions using flash photolysis of CH2I2-O-2-N-2 gas mixtures in the presence of excess co-reagent combined with monitoring of HCHO reaction products by laser-induced fluorescence (LIF) spectroscopy and, for the reaction with SO2, direct detection of CH2OO by photoionisation mass spectrometry (PIMS). Rate coefficients for CH2OO + SO2 and CH2OO + NO2 are independent of pressure in the ranges studied and are (3.42 +/- 0.42) x 10(-11) cm(3) s(-1) (measured between 1.5 and 450 Torr) and (1.5 +/- 0.5) x 10(-12) cm(3) s(-1) (measured between 25 and 300 Torr), respectively. The rate coefficient for CH2OO + CH3CHO is pressure dependent, with the yield of HCHO decreasing with increasing pressure. Upper limits of 2 x 10(-13) cm(3) s(-1) and 9 x 10(-17) cm(3) s(-1) are placed on the rate coefficients for CH2OO + NO and CH2OO + H2O, respectively. The upper limit for the rate coefficient for CH2OO + H2O is significantly lower than has been reported previously, with consequences for modelling of atmospheric impacts of CH2OO chemistry.