School of Chemistry, University of Leeds, UK LS2 9JT.
Phys Chem Chem Phys. 2009 Dec 14;11(46):10945-54. doi: 10.1039/b911745h. Epub 2009 Oct 14.
Silicon monoxide (SiO) is injected directly into the Earth's upper atmosphere by ablating meteoroids. SiO is also produced by the reaction of atomic Si (another ablation product) with O(2) and O(3). The reactions of SiO with several atmospherically relevant oxidants have been studied by the pulsed laser photolysis of a Si atom precursor in the presence of O(2), followed by time-resolved non-resonant laser-induced fluorescence of SiO at 282 nm. This yielded: k(SiO + O(3), 190-293 K) = (4.4 +/- 0.6) x 10(-13) cm(3) molecule(-1) s(-1); k(SiO + O(2) + He, 293 K) < or = 3 x 10(-32) cm(6) molecule(-2) s(-1), k(SiO + O + He, 293 K) < or = 1 x 10(-30) cm(6) molecule(-2) s(-1), k(SiO + H(2)O, 293 K, 4-20 Torr) < or = 4 x10(-14) cm(3) molecule(-1) s(-1), and k(SiO + OH, 293 K, 4-20 Torr) = (5.7 +/- 2.0) x 10(-12) cm(3) molecule(-1) s(-1). These results are explained by combining ab initio quantum chemistry calculations with transition state theory and RRKM theory. An upper limit of 5 x 10(-13) cm(3) molecule(-1) s(-1) for the reaction SiO(2) + O --> SiO + O(2) was determined, but calculations indicate the existence of a high barrier (104.7 kJ mol(-1)) which will make this reaction very slow at mesospheric temperatures.
一氧化硅（SiO）通过烧蚀流星体直接注入地球高层大气。SiO 也可以通过原子硅（另一种烧蚀产物）与 O(2)和 O(3)的反应产生。通过在存在 O(2)的情况下用脉冲激光烧蚀硅原子前体，并随后对 282nm 的 SiO 进行时间分辨非共振激光诱导荧光，研究了 SiO 与几种大气相关氧化剂的反应。这得出了：k(SiO + O(3)，190-293 K) = (4.4 +/- 0.6) x 10(-13) cm(3) molecule(-1) s(-1)；k(SiO + O(2) + He，293 K) < or = 3 x 10(-32) cm(6) molecule(-2) s(-1)，k(SiO + O + He，293 K) < or = 1 x 10(-30) cm(6) molecule(-2) s(-1)，k(SiO + H(2)O，293 K，4-20 Torr) < or = 4 x10(-14) cm(3) molecule(-1) s(-1)，k(SiO + OH，293 K，4-20 Torr) = (5.7 +/- 2.0) x 10(-12) cm(3) molecule(-1) s(-1)。这些结果通过将从头算量子化学计算与过渡态理论和 RRKM 理论相结合来解释。SiO(2) + O --> SiO + O(2) 反应的上限为 5 x 10(-13) cm(3) molecule(-1) s(-1)，但计算表明存在一个高势垒（104.7 kJ mol(-1)），这将使该反应在中层温度下非常缓慢。
