Dynamic in Situ Characterization of Organic Monolayer Formation via a Novel Substrate-Mediated Mechanism

Kevin S. Schneider, Wei Lu, Daniel R. Fosnacht, B. G. Orr, Mark M. Banaszak Holl

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14 Citations (Scopus)

Abstract

Ultrahigh vacuum scanning tunneling microscopy data investigating octylsilane (C 8H 17SiH 3) monolayer pattern formation on Au(111) are presented. The irregular monolayer pattern exhibits a 60 Å length scale. Formation of the octylsilane monolayer relaxes the Au(111) 23 × √3 surface reconstruction and ejects surface Au atoms. Au adatom diffusion epitaxially extends the Au(111) crystal lattice via step edge growth and island formation. The chemisorbed monolayer covers the entire Au surface at saturation exposure. Theoretical and experimental data suggest the presence of two octylsilane molecular adsorption phases: an atop site yielding a pentacoordinate Si atom and a surface vacancy site yielding a tetracoordinate Si atom. Theoretical simulations investigating two-phase monolayer self-assembly dynamics on a solid surface suggest pattern formation results from strain-induced spinodal decomposition of the two adsorption phases. Collectively, the theoretical and experimental data indicate octylsilane monolayer pattern formation is a result of interfacial Au-Si interactions and the alkyl chains play a negligible role in the monolayer pattern formation mechanism.

Original languageEnglish
Pages (from-to)1258-1268
Number of pages11
JournalLangmuir
Volume20
Issue number4
DOIs
Publication statusPublished - 17 Feb 2004
Externally publishedYes

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