title: Unique ordered domains of biphenylthiol self-assembled monolayers on Au(111).
abstract: The surface structure and adsorption conditions of biphenylthiol (BPT) self-assembled monolayers (SAMs) on Au(111) were examined using scanning tunneling microscopy (STM) and X-ray photoelectron microscopy (XPS). STM imaging revealed that the structural order of BPT SAMs formed in a 0.01 mM ethanol solution at 60 degrees C decreases with increasing immersion time. Interestingly, BPT SAMs formed after 30 min have unique ordered domains containing well-ordered (square root of 3 x square root of 3)R30 degrees structures and bright rows that are connected by small aggregated domains with a periodicity of approximately 10 angstroms, results that have never been observed for other thiol SAM systems. Distances between the bright rows were 20-35 angstroms. The bright small domains contained five or six BPT molecules each, which may have originated from differences in the adsorption orientations of biphenyl groups that were induced by localized interactions between them. XPS measurements for BPT SAMs on Au(111) showed the two sulfur peaks at 161.2 and 162.2 eV, implying the formation of chemisorbed monolayers. Our results are anticipated to be useful for understanding the formation and structure of BPT SAMs on gold surfaces.
authors.affiliation: Department of Chemistry, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791, Korea.
authors.forename: Hungu
authors.initials: H
authors.lastname: Kang
authors.forename: Dong Geun
authors.initials: DG
authors.lastname: Shin
authors.forename: Jin Wook
authors.initials: JW
authors.lastname: Han
authors.forename: Eisuke
authors.initials: E
authors.lastname: Ito
authors.forename: Masahiko
authors.initials: M
authors.lastname: Hara
authors.forename: Jaegeun
authors.initials: J
authors.lastname: Noh
mesh_terms: D001713:Biphenyl Compounds / Q000737:chemistry*; D003460:Crystallization / Q000379:methods*; D006046:Gold / Q000737:chemistry*; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D001713:Biphenyl Compounds; D046911:Macromolecular Substances; D013438:Sulfhydryl Compounds; D006046:Gold