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TU Dresden » Faculty of Mechanical Science and Engineering » Institute for Materials Science » Chair of Materials Science and Nanotechnology



Thursday, 12 November 2015
(at 13:00 in room 115, Hallwachsstr. 3)
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On-surface synthesis and characterization of carbon nanostructures

Thomas Dienel


EMPA - the Swiss Federal Laboratories for Materials Science and Technology, Switzerland
   






The covalent coupling of molecular precursors catalyzed by metal surfaces opened the rapidly evolving field of on-surface chemical synthesis. Tailored precursors allow the bottom-up synthesis of novel, technologically highly relevant materials such as atomically precise graphene nanoribbons (GNRs). Such GNRs can be covalently joined into larger units, creating junctions and heterojunctions. The electronic properties of the formed structures strongly depend on the exact atomic configuration and can be altered by subtle variations of the edge configuration of the incorporated GNRs. Non-contact atomic force microscopy with CO-functionalized tips provides the ultimate resolution to resolve structural changes and bond formations associated with the synthesis and cross-coupling of GNRs. Simultaneously acquired frequency-shift and current maps are combined with tight binding (TB) simulations to gain a comprehensive characterization, where non-planarity of the junctions obstructs the direct assignment. In the second part of my talk, I will discuss the potential of on-surface reactions on an atomically thin insulator – a well-defined monolayer of hexagonal boron nitride (h-BN) on metal. The required dehalogenation of the polyphenylene precursor I 6 ‐ CHP strongly correlates with its position on the corrugated h ‐ BN on Rh(111). Contrary to the immediate and complete dehalogenation on metals, the h-BN imposes a distinct abstraction sequence, which can be followed by scanning tunneling microscopy and density functional theory. The subsequent aryl-aryl coupling of the CHP remnant after dehalogenation allows the formation of extended oligomers. These insights to the catalytic properties of h-BN provide a better understanding of the limitations for the bottom-up fabrication of graphene on h-BN.

Announcement (pdf)


Invited by G. Cuniberti

Within the nanoSeminar

last modified: 2018.10.24 Mi
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