Issue 46, 2009

Kinetic studies of atmospherically relevant silicon chemistry. Part II:Silicon monoxide reactions

Abstract

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 O2 and O3. 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 O2, followed by time-resolved non-resonant laser-induced fluorescence of SiO at 282 nm. This yielded: k(SiO + O3, 190–293 K) = (4.4 ± 0.6) × 10−13 cm3 molecule−1 s−1; k(SiO + O2 + He, 293 K) ≤ 3 × 10−32 cm6 molecule−2 s−1, k(SiO + O + He, 293 K) ≤ 1 × 10−30 cm6 molecule−2 s−1, k(SiO + H2O, 293 K, 4–20 Torr) ≤ 4 ×10−14 cm3 molecule−1 s−1, and k(SiO + OH, 293 K, 4–20 Torr) = (5.7 ± 2.0) × 10−12 cm3 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 × 10−13 cm3 molecule−1 s−1 for the reaction SiO2 + OSiO + O2 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.

Graphical abstract: Kinetic studies of atmospherically relevant silicon chemistry. Part II: Silicon monoxide reactions

Supplementary files

Article information

Article type
Paper
Submitted
16 Jun 2009
Accepted
08 Sep 2009
First published
14 Oct 2009

Phys. Chem. Chem. Phys., 2009,11, 10945-10954

Kinetic studies of atmospherically relevant silicon chemistry. Part II: Silicon monoxide reactions

J. C. Gómez Martín, M. A. Blitz and J. M. C. Plane, Phys. Chem. Chem. Phys., 2009, 11, 10945 DOI: 10.1039/B911745H

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