Gómez Martín Juan C, Blitz Mark A, Plane John M C
School of Chemistry, University of Leeds, UK LS2 9JT.
Phys Chem Chem Phys. 2009 Jan 28;11(4):671-8. doi: 10.1039/b812946k.
Atomic silicon is generated by meteoric ablation in the Earth's upper atmosphere (70-110 km). The reactions of Si(3P(J)) atoms with several atmospherically relevant species were studied by the pulsed laser photolysis of a Si atom precursor (typically PheSiH3), followed by time-resolved laser induced fluorescence at 251.43 nm (Si(3p2 3P0 --> 4s 3P1)). This yielded: k(Si + O2, 190-500 K) = 9.49 x 10(-11) + 1.80 x 10(-10) x exp(-T/115 K) cm3 molecule(-1) s(-1) (uncertainty < or = +/- 15%), in good accord with recent high-level theoretical calculations but in marked disagreement with previous experimental work; k(Si + O3, 190-293 K) = (4.0 +/- 0.5) x 10(-10) cm3 molecule(-1) s(-1); k(Si + CO2, 293 K) < or = 1.2 x 10(-14) cm3 molecule(-1) s(-1); and k(Si + H2O, 293 K) < or = 2.6 x 10(-13) cm3 molecule(-1) s(-1). These results are explained using a combination of quantum chemistry calculations and long-range capture theory. The quenching rate coefficients k(Si(1D2) + N2, 293 K) = (4.0 +/- 0.7) x 10(-11) cm3 molecule(-1) s(-1) and k(Si(1D2) + H2O, 293 K) = (2.3 +/- 0.3) x 10(-10) cm3 molecule(-1) s(-1) were also determined.
原子硅是由地球高层大气（70 - 110千米）中的流星烧蚀产生的。通过对硅原子前体（通常为苯硅烷）进行脉冲激光光解，随后在251.43纳米处进行时间分辨激光诱导荧光（Si(3p2 3P0 --> 4s 3P1)），研究了Si(3P(J))原子与几种与大气相关的物种的反应。由此得出：k(Si + O2, 190 - 500 K) = 9.49 x 10(-11) + 1.80 x 10(-10) x exp(-T/115 K) 立方厘米·分子(-1)·秒(-1)（不确定度≤±15%），这与最近的高水平理论计算结果高度吻合，但与之前的实验工作存在显著差异；k(Si + O3, 190 - 293 K) = (4.0 ± 0.5) x 10(-10) 立方厘米·分子(-1)·秒(-1)；k(Si + CO2, 293 K) ≤ 1.2 x 10(-14) 立方厘米·分子(-1)·秒(-1)；以及k(Si + H2O, 293 K) ≤ 2.6 x 10(-13) 立方厘米·分子(-1)·秒(-1)。结合量子化学计算和长程捕获理论对这些结果进行了解释。还测定了猝灭速率系数k(Si(1D2) + N2, 293 K) = (4.0 ± 0.7) x 10(-11) 立方厘米·分子(-1)·秒(-1)和k(Si(1D2) + H2O, 293 K) = (2.3 ± 0.3) x 10(-10) 立方厘米·分子(-1)·秒(-1)。
