Adsorption of phenylacetylene on Si(100)-2×1: Reaction mechanism and formation of a styrene-like π-conjugation system

Abstract

The interactions of phentylacetylene and $\mathrm{p}\mathrm{h}\mathrm{e}\mathrm{n}\mathrm{y}\mathrm{l}\mathrm{a}\mathrm{c}\mathrm{e}\mathrm{t}\mathrm{y}\mathrm{l}\mathrm{e}\mathrm{n}\mathrm{e}\ensuremath{-}\ensuremath{\alpha}{\ensuremath{-}d}_{1}$ with $\mathrm{Si}(100)\ensuremath{-}2\ifmmode\times\else\texttimes\fi{}1$ have been studied as a model system to mechanistically understand the adsorption of conjugated \ensuremath{\pi}-electron aromatic substitutions on $\mathrm{Si}(100)\ensuremath{-}2\ifmmode\times\else\texttimes\fi{}1.$ Vibrational signatures show that phenylacetylene covalently binds to the surface through a [2+2]-like cycloaddition pathway between the external $\mathrm{C}\ensuremath{\equiv}\mathrm{C}$ and $\mathrm{Si}=\mathrm{Si}$ dimer, forming styrene-like conjugation structure which was further supported by the chemical-shift of C $1s$ core level. These experimental results are consistent with the density-functional theory $[\mathrm{B}3\mathrm{LYP}/6\ensuremath{-}311//+\mathrm{G}(\mathrm{d})]$ calculations. The resulting styrene-like conjugation structures may possibly be employed as an intermediate for further organic syntheses and fabrication of molecular architecture for modification and functionalization of Si surfaces, or as a monomer for polymerization on Si surfaces.