| In this thesis, we focused on investigations of templating of nano structures on monolayer graphene (MLG) on Ru(0001) and growth graphene nano structures on Ru(0001) with organic molecule as precursor.Disorientation between the epitaxially grown graphene and the Ru(0001) substrate results in the moire structure, which modulates the electronic structures of graphene with its period. Therefore, in this system the reactivity of graphene varies across the moire unit cell and promises ordered nanoclusters by selecting the proper nucleation sites on the graphene sheet.The graphene nanoribbon, as a qusi-1D structure, experiences quantum confinement on its width. Owing to their special edge shape, zigzag graphene nanoribbons can bear metallic edge states, and the band gap of armchair nanoribbons can be tuned with the width of ribbons.The processes of templating manganese nanoclusters and organic molecules with the moire structures were investigated by scanning tunneling microscopy (STM), respectively. It was found that the12×12moire structure and the other two distorted moires coexist when monolayer graphene grown on Ru(0001). At the initial stage of nucleation, different adsorption modes for Mn monomer, dimer and trimer guided by various moire periodicities were observed. Mn monomer was traped above the center of a carbon hexagon in the fcc region of the12x12moire structure, while Mn long-pair tends to dwell above the atop-carbon atoms at the edge of the fcc/hcp region of the other two distorted moires. Upon Mn coverage increasing, STM measurements revealed that Mn clusters exhibit detectable preference for adsorption sites on all the three different moires. The most favourable adsorption sites for Mn clusters are the fcc regions, where ordering of Mn clusters was observable, and the lateral size of the clusters are tunable with Mn coverage. A density functional theory (DFT) calculation showed an adsorption mode of Mn monomer on the12×12moire structure coincident with the STM results. The calculation also revealed that magnetism appears with a magnetic moment of3.79μβ for Mn monomer adsorption on MLG/Ru(0001). Emergence of2D Mn islands upon annealing results in uplifting of graphene layer by densely packed Mn islands. Formation of Mn islands on graphene instead of intercalation underneath graphene suggests that the interaction between Mn and graphene could be very different from that between Co and graphene. The investigation of adsorption of iron phthalocyanine molecules onto the moire structure revealed that the lateral variation of reactivity of the moire structure promises a distinct preference for adsorption sites of the molecules.The bottom-up fabrication of armchair graphene nanoribbons on Ru(0001) was investigated by using10,10’-dibromo-9,9’-bianthryl (DBBA) as precursor monomers. Upon deposition of DBBA on Ru(0001), the precursors adsorbed with their axes in two orthogonal directions, of which one is along Ru(0001) azimuths, the other is rotated with30degree with respect to Ru(0001) azimuths. Upon annealing at373K, graphene nanoribbons aligned along Ru(0001) azimuths emerge. Their lengths were trigged to the lattice of the30degree rotated graphene moire structure, whose sublattice possesses the same direction with that of the nanoribbon. These results suggest substantial interaction between graphene nanoribbons and the substrate. After annealing the sample at473K, dehydrogenation occured at the armchair edges of the nanoribbons, and graphene nano-flakes can be formed by the lateral attachment of the nanoribbons. The C-Ru registry of the graphene flakes on Ru(0001) can be identified with the appearing of the brightness modulation in the STM images. Further annealing of the sample at673K, the fcc/hcp-region-like flakes melted with the atop-region-like flakes, and coherent tiny graphene islands were formed. |
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