Benzaldehyde on Water-Saturated Si(001): Reaction with Isolated Silicon Dangling Bonds versus Concerted Hydrosilylation

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• 作者：D. Pierucci ; A. Naitabdi ; F. Bournel ; J.-J. Gallet ; H. Tissot ; S. Carniato ; F. Rochet ; U. K枚hler ; D. Laumann ; S. Kubsky ; M. G. Silly ; F. Sirotti
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：May 15, 2014
• 年：2014
• 卷：118
• 期：19
• 页码：10005-10016
• 全文大小：763K
• 年卷期：v.118,no.19(May 15, 2014)
• ISSN：1932-7455

文摘

Despite strong similarities due to the common presence of silicon monohydrides and isolated silicon dangling bonds (silicon radicals), the water-saturated Si(001)-2 脳 1 surface and the hydrogen-terminated Si(001)-2 脳 1 surface show very different reactivities with respect to benzaldehyde. By using real-time scanning tunneling microscopy, synchrotron radiation photoemission, X-ray absorption, and high-resolution electron energy loss spectroscopies in combination, we demonstrated that benzaldehyde reacts with the silicon dangling bonds of water-saturated Si (001). As we found no evidence for the abstraction of a nearby H leading to the formation of a new dangling bond, the formation of a stable radical adduct is a plausible explanation. This observation contrasts with the H-terminated case for which benzaldehyde grafting occurs via a radical chain reaction that can propagate after abstraction of a nearby H by the radical adduct. Also at odds with the H-terminated case, a second chemisorption channel is observed [i.e., a concerted hydrosilylation reaction between a surface monohydride (SiH) and the carbonyl moiety] without any participation of the silicon dangling bond. We discuss how the presence of hydroxyls on water-saturated Si(001)-2 脳 1 could make its reactivity markedly different from that of H-terminated Si(001)-2 脳 1.