Web Release Date: December 7,
Formation of Ordered Self-Assembled Monolayers by Adsorption of Octylthiocyanates on Au(111)
and
Department of Chemistry, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791, Korea, Emergent Functions Asian Collaboration Laboratory, Frontier Research System, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan, and Department of Electronic Chemistry, Tokyo Institute of Technology, 4259 Nagatsuta, Midoriku, Yokohama 226-8502, Japan
Received May 4, 2007
In Final Form: October 22, 2007
Abstract:
Self-assembled monolayers (SAMs) were formed by the spontaneous adsorption of octythiocyanate (OTC) on
Au(111) using both solution and ambient-pressure vapor deposition methods at room temperature and 50 
C. The
surface structures and adsorption characteristics of the OTC SAMs on Au(111) were characterized by scanning
tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). The STM observation showed that OTC
SAMs formed in solution at room temperature have unique surface structures including the formation of ordered and
disordered domains, vacancy islands, and structural defects. Moreover, we revealed for the first time that the adsorption
of OTC on Au(111) in solution at 50 C led to the formation of SAMs containing small ordered domains, whereas
the SAMs formed by vapor deposition at 50 C had long-range ordered domains, which can be described as (
3 ×
219)R5 structures. XPS measurements of the peaks in the S 2p and N 1s regions for the OTC SAMs showed that
vapor deposition is the more effective method as compared to solution deposition for obtaining high-quality SAMs
by adsorption of OTC on gold. The results obtained will be very useful in understanding the SAM formation of organic
thiocyanates on gold surfaces.
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