title: Self-assembly of alkanedithiols on Au(111) from solution: effect of chain length and self-assembly conditions.
abstract: A comparative study on the adsorption of buthanedithiol (BDT), hexanedithiol (HDT), and nonanedithiol (NDT) on Au(111) from ethanolic and n-hexane solutions and two different preparation procedures is presented. SAM characterization is based on reflection-absorption infrared spectroscopy, electrochemistry, X-ray photoelectron spectroscopy, and time of flight direct recoil spectroscopy. Results indicate that one can obtain a standing-up phase of dithiols and that the amount of the precursor lying-down phase decreases from BDT to NDT, irrespective of the solvent and self-assembly conditions. A good ordering of the hydrocarbon chains in the standing-up configuration is observed for HDT and NDT when the system is prepared in degassed n-hexane with all operations carried out in the dark. Disulfide bridges at the free SH terminal groups are formed for HDT and to a lesser extent for NDT prepared in ethanol in the presence of oxygen, but we found no evidence of ordered multilayer formation in our experiments. No disulfides were observed for BDT that only forms the lying-down phase. Our results demonstrate the key role of the chain length and the procedure (solvent nature and oxygen presence) in controlling the surface structure and chemistry of SAMs dithiols on Au(111).
authors.affiliation: Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas, 1900 La Plata, Buenos Aires, Argentina.
authors.forename: María Antonieta Daza
authors.initials: MA
authors.lastname: Millone
authors.forename: Hicham
authors.initials: H
authors.lastname: Hamoudi
authors.forename: Luis
authors.initials: L
authors.lastname: Rodríguez
authors.forename: Aldo
authors.initials: A
authors.lastname: Rubert
authors.forename: Guillermo A
authors.initials: GA
authors.lastname: Benítez
authors.forename: María Elena
authors.initials: ME
authors.lastname: Vela
authors.forename: Roberto C
authors.initials: RC
authors.lastname: Salvarezza
authors.forename: J Esteban
authors.initials: JE
authors.lastname: Gayone
authors.forename: Esteban A
authors.initials: EA
authors.lastname: Sánchez
authors.forename: Oscar
authors.initials: O
authors.lastname: Grizzi
authors.forename: Céline
authors.initials: C
authors.lastname: Dablemont
authors.forename: Vladimir A
authors.initials: VA
authors.lastname: Esaulov