Surface phase behavior of n-alkanethiol self-assembled monolayers adsorbed on Au(111): An atomic force microscope study

Kaoru Tamada, Masahiko Hara, Hiroyuki Sasabe, Wolfgang Knoll

研究成果: Article査読

245 被引用数 (Scopus)

抄録

n-Alkanethiol (CnH2n+1SH) self-assembled monolayers (SAMs) adsorbed on Au(111) were studied with an atomic force microscope (AFM) to confirm the influence of the lateral interaction between adsorbed thiols on the film morphology. Two experiments were performed: firstly, a study of the domain formation at the initial stage of SAM growth (single component) and, secondly, investigations of the coadsorption phenomenon in mixed SAMs composed of two alkanethiols having different chain lengths. For the kinetics study, Au(111) was immersed into the 10-2 mM ethanol solutions with the single component alkanethiol (C4H9SH, C12H25SH, or C18H37SH), for varying times (1 s to 10 min). In all cases, the film coverage increased as the immersion time became longer, and finally the surface was totally covered with thiols after an immersion time of 3 min or more. Clear island formations were observed in the partially covered C12H25SH and C18H37SH SAMs, while C4H9SH formed meshlike domains. The mixed SAMs were prepared by immersing Au(111) into 1 mM ethanol solutions with mixed alkanethiols (C4H9SH/C18H37SH) of various compositions, Rsoln = [C4H9SH]/[C18H37SH] = 1/1 to 100/1, for a time of 1 h. Clear phase separation was observed at Rsoln = 20/1 and 40/1. Above or below these compositions, the film surface appeared very flat, covered with a nearly single component, C4H9SH or C18H37SH, respectively. This is the first systematic study of the surface phase behavior of alkanethiol SAMs by AFM imaging. It reveals more direct information about the film morphology than previous studies with conventional surface analytical techniques such as X-ray photoelectron spectroscopy, ellipsometry, contact angles, etc.

本文言語English
ページ(範囲)1558-1566
ページ数9
ジャーナルLangmuir
13
6
DOI
出版ステータスPublished - 1997 3 19
外部発表はい

ASJC Scopus subject areas

  • 材料科学(全般)
  • 凝縮系物理学
  • 表面および界面
  • 分光学
  • 電気化学

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