title: In situ STM study of potential-driven transitions in the film of a cationic surfactant adsorbed on a Au(111) electrode surface.
abstract: Electrochemical scanning tunneling microscopy (EC-STM) has been employed to study the structure of a film formed by cationic surfactant N-decyl-N,N,N-trimethylammonium triflate (DeTATf) adsorbed on the Au(111) electrode surface. The film is disordered at potentials corresponding to either large negative charge densities or to positive charge densities. At small negative charge densities, an ordered adlayer of flat-lying DeTATf molecules is formed. High-resolution images of this adlayer reveal that the triflate anion is coadsorbed with the N-decyl-N,N,N-trimethylammonium cation, effectively forming an ion pair at the electrode surface. This is a significant result because it explains why this surfactant behaves like a zwitterionic surfactant at the metal/solution interface.
authors.affiliation: Department of Chemistry, University of Guelph, Guelph, ON, Canada.
authors.forename: Slawomir
authors.initials: S
authors.lastname: Sek
authors.forename: Maohui
authors.initials: M
authors.lastname: Chen
authors.forename: Christa L
authors.initials: CL
authors.lastname: Brosseau
authors.forename: Jacek
authors.initials: J
authors.lastname: Lipkowski
mesh_terms: D000327:Adsorption; D002412:Cations / Q000737:chemistry; D004566:Electrodes; D006046:Gold / Q000737:chemistry*; D008567:Membranes, Artificial; D016252:Microscopy, Scanning Tunneling / Q000379:methods*; D008958:Models, Molecular; D013499:Surface Properties; D013501:Surface-Active Agents / Q000737:chemistry*
chemical_list: D002412:Cations; D008567:Membranes, Artificial; D013501:Surface-Active Agents; D006046:Gold