| With its excellent optical,thermodynamic and electronic properties,graphene has great significance and application prospects in the basic research and development of new materials.The method of bottom-up fabrication of graphene is an advanced method that can better meet special requirements.Among many transition metal substrates,Ru(0001)is one of the most commonly used substrates for growing high-quality graphene.Due to the strong interaction with graphene and substrate,many different moiré superstructures are formed.The research about the physical mechanism and structural characteristics of graphene with different moiré superstructures on Ru(0001)will not only promote further research on the growth of special graphene on Ru(0001)substrates,but also expand the application of graphene/Ru(0001).In this thesis,we used scanning tunnel microscope(STM)as an experimental observation method to study the adsorption behavior of 9,9’-dixanthylidene on Ru(0001)and the result of graphene self-assembly with 9,9’-dixanthylidene as the precursor.The 9,9’-dixanthylidene molecule was thermally evaporated onto Ru(0001),and the adsorption behavior of the molecule was observed and calculated under the submonolayer system.The sample was annealed to obtain self-assembled graphene,and the moire superstructures of graphene on Ru(0001)at three different rotation angles(6.3°,13.9° and 16.1°)were found.The mechanism and properties of these three superstructures were simulated and analyzed.The results show that the average periodicity of the superstructure with 6.3° angle is about 1.826 nm,and the vertical height rise is about 1.44 nm.The correctness of the judgment is verified through the building and calculation of the atomic model.The average periodicity of the 13.9°and 16.1°angular graphene molecular superstructures is about 0.998 nm and 1.525 nm,respectively.Their third degree symmetry is more obvious,and the wrinkles are smaller,showing different molecular morphologies. |
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