Berlin 2018 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 64: Focus Session: Molecular Nanostructures on surfaces - New Concepts towards Complex Architectures IV

O 64.3: Vortrag

Mittwoch, 14. März 2018, 15:30–15:45, MA 004

Surface induced asymmetric activation of 4,4''-Diamino-p-terphenyl on Cu(111): symmetry breakdown by lattice mismatch — Qigang Zhong¹, •Daniel Ebeling², Jalmar Tschakert², Yixuan Gao³, Deliang Bao³, Shixuan Du³, Lifeng Chi¹, and Andre Schirmeisen² — ¹Institute of Functional Nano & Soft Materials, Soochow University, Suzhou, China — ²Institute of Applied Physics, Justus-Liebig University, Giessen, Germany — ³Institute of Physics, Chinese Academy of Sciences, Beijing, China

We demonstrate that asymmetric activation of the mirror symmetric molecule 4,4''-Diamino-p-terphenyl (DATP) is possible on a metal surface. Our low temperature atomic force microscopy images, using CO-tip functionalization, show that on Cu(111) the DATP the adsorption geometry becomes asymmetric for certain orientations, while on Au(111) the symmetry is fully retained. This symmetry breaking on Cu(111) is caused by a lattice mismatch between the molecule and the metal surface, corroborated by interactions with the subsurface atomic layer. The asymmetric DATP molecules show non-stationary behavior under the influence of the scanning tip, which leads to a bi-level telegraph noise, here serving as a fingerprint of the surface induced asymmetry. Dispersion corrected DFT-D2 computations confirm the precise topology, the dynamics, and the energy barriers of the observed asymmetric adsorption geometries. Finally, we exploit the asymmetric activation of DATP for side-preferential attachment of 2-triphenylenecarbaldehyde (TPCA). Our findings provide a new route for surface induced asymmetric activation of a symmetric compound.