How Adsorbate Alignment Leads to Selective Reaction
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- 作者：Fang Cheng ; Wei Ji ; Lydie Leung ; Zhanyu Ning ; John C. Polanyi ; Chen-Guang Wang
- 刊名：ACS Nano
- 出版年：2014
- 出版时间：August 26, 2014
- 年：2014
- 卷：8
- 期：8
- 页码：8669-8675
- 全文大小：446K
- ISSN：1936-086X
文摘
There has been much interest in the effect of adsorbate alignment in a surface reaction. Here we show its significance for an electron-induced reaction occurring along preferred axes of the asymmetric Cu(110) surface, characterized by directional copper rows. By scanning tunneling microscopy (STM), we found that the heterocyclic aromatic reagent, physisorbed meta-iodopyridine, lay with its carbon鈥搃odine either along the rows of Cu(110), 鈥淎鈥? or perpendicular, 鈥淧鈥? Electron-induced dissociative attachment with the C鈥揑 bond initially along 鈥淎鈥?gave a chemisorbed I atom and chemisorbed vertical pyridyl, singly surface-bound, whereas that with C鈥揑 along 鈥淧鈥?gave a chemisorbed I atom and a horizontal pyridyl, doubly bound. An impulsive two-state model, involving a short-lived antibonding state of C鈥揑, accounted for the different product surface binding in terms of closer Cu路路路Cu atomic spacing along 鈥淎鈥?accommodating only one binding site of the pyridyl ring recoiling from I and wider spacing along 鈥淧鈥?accommodating simultaneously both binding sites, N鈥揅u and C鈥揅u, in the meta-position on the recoiling pyridyl ring. STM studies combined with dynamical modeling can be seen as a way to improve understanding of the role of surface alignment in determining reactive outcomes in induced reaction at asymmetric crystalline surfaces.