title: Hydration of hydrophilic thiolate monolayers visualized by atomic force microscopy.
abstract: Monolayers of mercaptoundecanol and mercaptoundecanoic acid were prepared on Au(111) films, immersed in aqueous solutions, and probed by frequency-modulation atomic force microscopy. The pN-order tip-surface force was observed over the monolayers as a function of vertical and lateral coordinates, together with the topography of the monolayers. The observed force distribution was modulated between adjacent OH endgroups in the mercaptoundecanol monolayer, as opposed to on top of COOH and COO(-) endgroups in the mercaptoundecanoic acid monolayer. Models of the interfacial hydrogen bond between water and the endgroups were proposed. The force distribution was insensitive to the electrolyte composition. There was no qualitative sign of tip-induced confinement of water.
authors.affiliation: Department of Chemistry, Graduate School of Science, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan. hiasa@stu.kobe-u.ac.jp
authors.forename: Takumi
authors.initials: T
authors.lastname: Hiasa
authors.forename: Kenjiro
authors.initials: K
authors.lastname: Kimura
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Onishi
mesh_terms: D004573:Electrolytes / Q000737:chemistry; D006046:Gold / Q000737:chemistry; D006860:Hydrogen Bonding; D057927:Hydrophobic and Hydrophilic Interactions; D018625:Microscopy, Atomic Force; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D004573:Electrolytes; D013438:Sulfhydryl Compounds; D014867:Water; D006046:Gold