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- Title
Directed long-range molecular migration energized by surface reaction.
- Authors
Harikumar, K. R.; Polanyi, John C.; Zabet-Khosousi, Amir; Czekala, Piotr; Haiping Lin; Hofer, Werner A.
- Abstract
The recoil of adsorbates away (desorption) and towards (reaction) surfaces is well known. Here, we describe the long-range recoil of adsorbates in the plane of a surface, and accordingly the novel phenomenon of reactions occurring at a substantial distance from the originating event. Three thermal and three electron-induced surface reactions are shown by scanning tunnelling microscopy to propel their physisorbed ethylenic products across the rough surface of Si(100) over a distance of up to 200 Å before an attachment reaction. The recoil energy in the ethylenic products comes from thermal exoergicity or from electronic excitation of chemisorbed alkenes. We propose that the mechanism of migration is a rolling motion, because the recoiling molecule overcomes raised surface obstacles. Electronic excitation of propene causes directional recoil and often end-to-end inversion, suggesting cartwheeling. Ab initio calculations of the halogenation and electron-induced reactions support a model in which asymmetric forces between the molecule and the surface induce rotation and therefore migration.
- Subjects
DESORPTION; SURFACE chemistry; ELECTRONIC excitation; ETHYLENE; CHEMICAL bonds; PROPENE; LASER spectroscopy; HETEROGENEOUS catalysis; PHASE separation method (Engineering); CHEMICAL structure
- Publication
Nature Chemistry, 2011, Vol 3, Issue 5, p400
- ISSN
1755-4330
- Publication type
Article
- DOI
10.1038/nchem.1029