title: Self-assembled monolayers on Pt(111): molecular packing structure and strain effects observed by scanning tunneling microscopy.
abstract: Self-assembled monolayers (SAMs) of octanethiol and benzeneethanethiol were deposited on clean Pt(111) surfaces in ultrahigh vacuum (UHV). Highly resolved images of these SAMs produced by an in situ scanning tunneling microscope (STM) showed that both systems organize into a super-structure mosaic of domains of locally ordered, closely packed molecules. Analysis of the STM images indicated a (square root 3 x square root 3)R30 degrees unit cell for the octanethiol SAMs and a 4(square root 3 x square root 3)R30 degrees periodicity based on 2 x 2 basic molecular packing for the benzeneethanethiol SAMs under the coverage conditions investigated. SAMs on Pt(111) exhibited differences in molecular packing and a lower density of disordered regions than SAMs on Au(111). Electron transport measurements were performed using scanning tunneling spectroscopy. Benzeneethanethiol/Pt(111) junctions exhibited a higher conductance than octanethiol/Pt(111) junctions.
authors.affiliation: Department of Chemical Engineering and Materials Science, University of California, Irvine, California 92697, USA.
authors.forename: Sangyeob
authors.initials: S
authors.lastname: Lee
authors.forename: Jung
authors.initials: J
authors.lastname: Park
authors.forename: Regina
authors.initials: R
authors.lastname: Ragan
authors.forename: Sehun
authors.initials: S
authors.lastname: Kim
authors.forename: Zonghoon
authors.initials: Z
authors.lastname: Lee
authors.forename: Do Kyung
authors.initials: DK
authors.lastname: Lim
authors.forename: Douglas A A
authors.initials: DA
authors.lastname: Ohlberg
authors.forename: R Stanley
authors.initials: RS
authors.lastname: Williams