AVS 51st International Symposium
    Surface Science Tuesday Sessions
       Session SS2-TuM

Paper SS2-TuM11
Comparative UHV-STM Study of Adsorption Structures Formed from a Family of Oligo(phenylene ethynylene)s on Au(111)

Tuesday, November 16, 2004, 11:40 am, Room 210C

Session: Self Assembled Monolayers
Presenter: T.R. Linderoth, University of Aarhus, Denmark
Authors: L. Petersen, University of Aarhus, Denmark
C. Busse, University of Aarhus, Denmark
S. Terkelsen, University of Aarhus, Denmark
T.R. Linderoth, University of Aarhus, Denmark
M. Nielsen, University of Aarhus, Denmark
K.V. Gothelf, University of Aarhus, Denmark
F. Besenbacher, University of Aarhus, Denmark
Correspondent: Click to Email
To realize the goal of functional structures formed by molecular self-assembly, systematic studies of factors directing the assembly process are required. Using UHV-STM we have performed a comparative study of adsorption structures formed by a family of structurally different, but chemically similar, organic molecules adsorbed on the Au(111) surface. The molecules consist of a central benzene ring with three or two acetylene spokes (para, meta, or ortho) leading to highly conjugated pi-systems of three-spoke, linear, bent, or v-shaped molecular geometry. Each spoke terminates in a tert-butyl substituted salicylaldehyde moiety. Upon adsorption at room temperature (and imaging at ~150 K to reduce molecular mobility), a variety of close-packed phases are observed, most of which can be rationalized by a common motif of molecules adsorbed with their backbone parallel to the surface and with optimized intermolecular side-to-side interaction, most likely through van der Waals coupling. Interesting exceptions to this picture are the linear molecules, which in addition form a more open nano-grid type structure thought to be dominated by intermolecular hydrogen bonding, and the v-shaped molecules where a reduced footprint indicates non-planar adsorption geometry. The described results constitute a platform for ongoing experiments where (i) similar molecules with systematically altered functional moieties are used, e.g. disabling or further encouraging intermolecular hydrogen bond formation, (ii) structures formed through co-adsorption with transition metals (Ni,Fe) are investigated, and (iii) intermolecular covalent cross-linking is induced through co-adsorption with reactive diamines.