Formation and Nanostructure of Alkanethiol and Fluorinated Alkanethiol Self-Assembled Monolayers on Au(111)

Abstract

Fluorine-terminated thiols are of great interest since fluorine atoms have inherent properties such as inertness to most chemical reagents, low friction coefficient and excellent repellency. In this study, the formation and structures of self-assembly monolayers(SAMs) prepared by propanethiol (PT) and trifluoropropanethiol (TFPT) on Au(111) were examined and compared using scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry (CV) to explore the structure and electronic interface properties of differently substituted alkanethiol SAMs on Au(111). STM observation showed that the PT and TFPT SAMs formed at 70 0C for 10 min and 20 min, have very uniform surface structure and ordered domains compared to those formed at other immersion temperature and time. The TFPT SAMs formed after 20 min have unique ordered domains containing well-ordered structures. XPS measurements for PT and TFPT SAMs show that sulfur atoms are chemically bond to the gold surface. Therefore, we can find that the surface structure of short-chain alkanethiol SAMs is quite changed according to whether or not the terminal group of short-chain alkanethiol SAMs is functionalized with fluorine atom