Reaction Sites of CO on Size-Selected Silicon Oxide Cluster Anions: A Model Study of Chemistry in the Interstellar Environment

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• 作者：Masashi Arakawa ; Ryo Yamane ; Akira Terasaki
• 刊名：Journal of Physical Chemistry A
• 出版年：2016
• 出版时间：January 14, 2016
• 年：2016
• 卷：120
• 期：1
• 页码：139-144
• 全文大小：466K
• ISSN：1520-5215

文摘

We present reactions of size-selected free silicon oxide cluster anions, Si_nO_m^– (n = 3–7, 2n – 1 ≤ m ≤ 2n + 2), with a CO gas. Adsorption of CO on Si_nO_m^– is observed as a major reaction channel. The rate constant of the adsorption reaction is high for the oxygen-rich clusters with m ≥ 2n + 1, whereas almost no reaction product is observed for m ≤ 2n. DFT calculations revealed that a pair of dangling O atoms on 4-fold-coordinated Si atoms plays a key role, which is the adsorption site of CO on Si_nO_m^–. Bond formation between CO and one of the dangling O atoms is associated with electron transfer from the CO molecule to the other dangling O atom. The present findings give molecular-level insights into adsorption of CO molecules on silicates in the interstellar environment.