Structural And Electronic Properties Of C₆₀ And Gd@C₈₂on Cu（111） And Pt（111）

With the development of integrated circuits industry, single-molecule functional devices became one of research hotspots. The electronic properties of the molecule are affected not only by its own structural characteristics, but also by its local adsorption sites and orientation relative to the solid surface. Duo to its special cage-like structure fullerene molecules has good stability. The significant charge transfer caused by metal atoms embedded in the fullerene cages greatly changes the electrical and magnetic properties of the metallofullerene molecule, which attracts much attention in molecular electronic devices. In this dissertation, the growth structures and electronic properties of fullerenes C6o and Gd@Cg2on metal substrates were studied by scanning tunneling microscope (STM).1. The self-assembled structures of C60molecules adsorbed on Cu(111) at low temperature and their effect on the interfacial structures were studied. We found five kinds of non-equivalent adsorption configurations on non-reconstructed substrate and built the relationship among them according to the molecular resolution STM images. The bonding energy of each C6o located in different positions of Cu(111) surface were calculated by DFT theory, based on which the specific adsorption configuration models were proposed. It has been found that C6o molecules induce the surface reconstruction of Cu(111) from the STM images of self-assembly C6o islands upon annealing treatments at different temperatures. Based on that, we are the first to confirm the transformational process from the metastable self-assembled structures of C6o islands to the stable (4×4) structure.2. Through the systematic study and comparison of the adsorption structures and electronic properties of C6o islands deposited on Cu(111) and Pt(111) at low temperature, we found that the growth pattern of Gd@Cg2on both substrates were quite different:Gd@C82preferentially adsorbed on the low-energy areas (such as edge of steps and defects) of Cu(111) with Volmer-Weber (3D) growth mode while they randomly distributed on Pt(111) with layer-by-layer growth mode. After annealing, Gd@C82molecules formed two kinds of close packing arrangements on both substrates. Upon Gd@Cg2adsorption Cu(111) was reconstructed while on Pt(111) no reconstruction happened. From the STM images of Gd@C82and defects (impurities) at different bias voltages, we had identified that the electronic properties was influenced not only by the adsorption orientation of Gd@C82but also by the defects and impurities on Cu(111) surface. Combined the STS measurements with the DFT theoretical calculations, the local density of states of a minority fraction of Gd@C82molecules are perturbed by the incorporation with the species preexisted on Cu(111) such as atomic oxygen, atomic carbon, carbon monoxide and oxygen. From the detection and imaging of Gd@C82on Pt(111) by differential conductance spectrum/mapping, we confirmed the location of the Gd atom within the Gd@C82.3. We have investigated the effects of lattice-mismatching induced periodic polar surface potential of FeO/Pt(111) thin film on the adsorption strctures and electronic states of C6o and Gd@C82. This periodic surface potential effects not only the adsorption orientation of C6o molecules to form (V133xV133)R17.5°long-range superlattice, but also the electronic state of C6o to result in the final formation of the8x8superlattice ordering with dim-bright STM contrast. Due to the modulation effect of the FeO/Pt(111) polar surface potential, Gd@C82molecules selectively adsorbed on the hcp and fcc positions of Moire pattern. The apparent height of a single Gd@C82is much lower than its geometry diameter because of the dipolar interactions between polar surface potential of FeO film and the polar molecule Gd@C82.