title: Selective binding, self-assembly and nanopatterning of the Creutz-Taube ion on surfaces.
abstract: The surface attachment properties of the Creutz-Taube ion, i.e., [(NH(3))(5)Ru(pyrazine)Ru(NH(3))(5)](5+), on both hydrophilic and hydrophobic types of surfaces were investigated using X-ray photoelectron spectroscopy (XPS). The results indicated that the Creutz-Taube ions only bound to hydrophilic surfaces, such as SiO(2) and -OH terminated organic SAMs on gold substrates. No attachment of the ions on hydrophobic surfaces such as -CH(3) terminated organic SAMs and poly(methylmethacrylate) (PMMA) thin films covered gold or SiO(2) substrates was observed. Further ellipsometric, atomic force microscopy (AFM) and time-dependent XPS studies suggested that the attached cations could form an inorganic analog of the self-assembled monolayer on SiO(2) substrate with a "lying-down" orientation. The strong electrostatic interaction between the highly charged cations and the anionic SiO(2) surface was believed to account for these observations. Based on its selective binding property, patterning of wide ( approximately 200 nm) and narrow ( approximately 35 nm) lines of the Creutz-Taube ions on SiO(2) surface were demonstrated through PMMA electron resist masks written by electron beam lithography (EBL).
authors.affiliation: Department of Chemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA.
authors.forename: Yuliang
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Chemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA.
authors.forename: Marya
authors.initials: M
authors.lastname: Lieberman
authors.affiliation: Department of Electric Engineering, University of Notre Dame, Notre Dame, Indiana 46556, USA.
authors.forename: Qingling
authors.initials: Q
authors.lastname: Hang
authors.affiliation: Department of Electric Engineering, University of Notre Dame, Notre Dame, Indiana 46556, USA.
authors.forename: Gary
authors.initials: G
authors.lastname: Bernstein