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O: Fachverband Oberflächenphysik

O 11: Focus Session: Molecular Nanostructures on surfaces - New Concepts towards Complex Architectures I

O 11.4: Vortrag

Montag, 12. März 2018, 16:00–16:15, MA 004

Topological modifications in graphene nanostructures — •Shantanu Mishra, Carlo A. Pignedoli, Pascal Ruffieux, and Roman Fasel — Empa - Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland

Graphene is the first two-dimensional crystal discovered in nature. The interesting properties of graphene arise from the sp2-network of carbon atoms and a perfect arrangement of hexagonal rings. Like any other crystal, presence of defects disrupting the pristine topology should significantly impact the physical properties of graphene. Introduction of defects thus provides a platform to tailor intrinsic properties of graphene and mandates a rational approach to achieve atomic-scale control over construction and implementation of defects for device applications. Regarding this, on-surface Ullmann reaction has become an indispensable synthetic tool to achieve atomically precise synthesis of nanostructures.

Utilizing this synthetic procedure, we fabricate two novel graphene nanostructures. The first is a non-alternant polyaromatic hydrocarbon demonstrating the first rational synthesis of the inverse Stone-Thrower-Wales defect in graphene. The second structure constitutes an organic polymer with precise substitution of specific carbon atoms with nitrogen atoms, that presents a model case for doping of graphene nanostructures with possible introduction of magnetism. Using a combined scanning tunneling microscopy and density functional theory based study, we investigate the novel properties that these altered bond or atomic topologies impart to nanographenes.