Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA.
J Am Chem Soc. 2010 Mar 10;132(9):3013-9. doi: 10.1021/ja909139n.
Using ultrahigh vacuum (UHV) scanning tunneling microscopy (STM), many olefins have been shown to self-assemble on the hydrogen-passivated Si(100)-2 x 1 surface into one-dimensional nanostructures. This paper demonstrates that similar one-dimensional nanostructures can also be realized using alkynes. In particular, UHV STM, sum frequency generation (SFG), and density functional theory (DFT) are employed to study the growth mechanism and binding configuration of phenylacetylene (PA) one-dimensional nanostructures on the Si(100)-2 x 1:H surface. Molecular-resolution UHV STM images reveal the binding position and spacing of PA with respect to the underlying silicon dimer rows. Furthermore, UHV STM characterization of heteromolecular one-dimensional nanostructures of styrene and PA shows distinct electronic contrast between the two molecules, which is confirmed using simulated STM images derived from DFT and provides insight into the nature of PA binding to silicon. Additional evidence from SFG measurements corroborates the conclusion that the terminal carbon atoms of PA retain pi-conjugation following reaction to the Si(100)-2 x 1:H surface.
利用超高真空（UHV）扫描隧道显微镜（STM），已经证明许多烯烃在氢钝化的 Si(100)-2x1 表面上自组装成一维纳米结构。本文证明，炔烃也可以实现类似的一维纳米结构。具体来说，采用 UHV STM、和密度泛函理论（DFT）研究了苯乙炔（PA）一维纳米结构在 Si(100)-2x1:H 表面上的生长机制和结合构型。分子分辨率的 UHV STM 图像揭示了 PA 相对于底层硅二聚体行的结合位置和间距。此外，对苯乙烯和 PA 的异分子一维纳米结构的 UHV STM 表征显示出两个分子之间存在明显的电子对比度，这通过源自 DFT 的模拟 STM 图像得到证实，并为 PA 与硅的结合性质提供了深入了解。来自 SFG 测量的额外证据证实了这样的结论，即 PA 的末端碳原子在与 Si(100)-2x1:H 表面反应后仍保留 π 共轭。
