Berlin 2018 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 109: Focus Session: Molecular Nanostructures on surfaces - New Concepts towards Complex Architectures VII

O 109.2: Vortrag

Freitag, 16. März 2018, 10:45–11:00, MA 004

construction of sierpiński triangles up to the fifth order — Chao Li, Xue Zhang, Na Li, •Jiajia Yang, and Yongfeng Wang — Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics, Peking University, Beijing 100871, China

Self-similar fractal structures are crucial in science, mathematics, and aesthetics. Recently, a series of molecular defect-free fractals of Sierpiński Triangles (STs) have been constructed on surfaces. In those previous experiments, the highest order of STs is simply 4th due to the random formation of nucleation centers and the limitation of kinetic growth. The growth mechanism of STs was investigated by low-temperature scanning tunneling microscopy. Here, we used a templating method to guide the formation of nucleation centers and co-assembly method to overcome the kinetic-growth limitation and control the formation of STs. Owing to the templating effect of the reconstructed Au(100)-(hex) substrate, Fe atoms, 4,4”-dicyano-1,1’:3’,1”terphenyl (C3PC), and 1,3-bis(4-pyridyl)benzene (BPyB) molecules were used to build fractals. According to our experiments, the proper C3PC : BPyB ratio is need to obtain the 5th-order STs. When C3PC molecules dominate, it tends to form a 1D crystalline chain structure. With large rate of BPyB to C3PC, the surface structures are determined by BPyB molecules and only small STs are obtained. The new strategy may be applied to construct various Sierpiński triangles of higher orders.