title: Intermixed adatom and surface-bound adsorbates in regular self-assembled monolayers of racemic 2-butanethiol on Au(111).
abstract: In situ scanning tunneling microscopy combined with density functional theory molecular dynamics simulations reveal a complex structure for the self-assembled monolayer (SAM) of racemic 2-butanethiol on Au(111) in aqueous solution. Six adsorbate molecules occupy a (10×√3)R30° cell organized as two RSAuSR adatom-bound motifs plus two RS species bound directly to face-centered-cubic and hexagonally close-packed sites. This is the first time that these competing head-group arrangements have been observed in the same ordered SAM. Such unusual packing is favored as it facilitates SAMs with anomalously high coverage (30%), much larger than that for enantiomerically resolved 2-butanethiol or secondary-branched butanethiol (25%) and near that for linear-chain 1-butanethiol (33%).
authors: School of Chemistry F11, The University of Sydney, NSW 2006 (Australia). rhouyng@dicp.ac.cn.
authors: Runhai
authors: R
authors: Ouyang
authors: Jiawei
authors: J
authors: Yan
authors: Palle S
authors: PS
authors: Jensen
authors: Erhad
authors: E
authors: Ascic
authors: Shiyu
authors: S
authors: Gan
authors: David
authors: D
authors: Tanner
authors: Bingwei
authors: B
authors: Mao
authors: Li
authors: L
authors: Niu
authors: Jingdong
authors: J
authors: Zhang
authors: Chunguang
authors: C
authors: Tang
authors: Noel S
authors: NS
authors: Hush
authors: Jeffrey R
authors: JR
authors: Reimers
authors: Jens
authors: J
authors: Ulstrup
mesh_terms: D000327:Adsorption; D006046:Gold / Q000737:chemistry*; D016252:Microscopy, Scanning Tunneling; D056004:Molecular Dynamics Simulation; D010316:Particle Size; D013237:Stereoisomerism; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D013438:Sulfhydryl Compounds; D006046:Gold; C025540:n-butyl mercaptan
keywords: density functional theory; dispersion; scanning tunneling microscopy; steric effects; thiolate