铂（111）表面的自组装单分子层：通过扫描隧道显微镜观察到的分子堆积结构和应变效应

Self-assembled monolayers on Pt(111): molecular packing structure and strain effects observed by scanning tunneling microscopy.

作者信息

Lee Sangyeob, Park Jung, Ragan Regina, Kim Sehun, Lee Zonghoon, Lim Do Kyung, Ohlberg Douglas A A, Williams R Stanley

机构信息

Department of Chemical Engineering and Materials Science, University of California, Irvine, California 92697, USA.

出版信息

J Am Chem Soc. 2006 May 3;128(17):5745-50. doi: 10.1021/ja058037c.

DOI:10.1021/ja058037c

PMID:16637642

Abstract

Self-assembled monolayers (SAMs) of octanethiol and benzeneethanethiol were deposited on clean Pt(111) surfaces in ultrahigh vacuum (UHV). Highly resolved images of these SAMs produced by an in situ scanning tunneling microscope (STM) showed that both systems organize into a super-structure mosaic of domains of locally ordered, closely packed molecules. Analysis of the STM images indicated a (square root 3 x square root 3)R30 degrees unit cell for the octanethiol SAMs and a 4(square root 3 x square root 3)R30 degrees periodicity based on 2 x 2 basic molecular packing for the benzeneethanethiol SAMs under the coverage conditions investigated. SAMs on Pt(111) exhibited differences in molecular packing and a lower density of disordered regions than SAMs on Au(111). Electron transport measurements were performed using scanning tunneling spectroscopy. Benzeneethanethiol/Pt(111) junctions exhibited a higher conductance than octanethiol/Pt(111) junctions.

摘要

在超高真空（UHV）环境下，将正辛硫醇和苯乙硫醇的自组装单分子层（SAMs）沉积在清洁的Pt(111)表面上。通过原位扫描隧道显微镜（STM）获得的这些SAMs的高分辨率图像显示，这两个体系都组织成由局部有序、紧密堆积分子的畴组成的超结构镶嵌图案。对STM图像的分析表明，在所研究的覆盖条件下，正辛硫醇SAMs的单位晶胞为（√3×√3）R30°，而苯乙硫醇SAMs基于2×2基本分子堆积具有4（√3×√3）R30°的周期性。与在Au(111)上的SAMs相比，Pt(111)上的SAMs在分子堆积上存在差异，且无序区域的密度更低。使用扫描隧道谱进行了电子输运测量。苯乙硫醇/Pt(111)结的电导高于正辛硫醇/Pt(111)结。