| Summary: | 碩士 === 國立臺灣大學 === 化學研究所 === 103 === Adsorbate-substrate interactions are important and typical subjects in surface science because the interactions modulate the electronic structures of the adsorbate and thus offer a tactic to modify the interfacial properties. At step edges, in addition to the underneath substrate, lateral interactions from the vertical face of the step come into play. In this thesis work of C60, a bimetallic step edge was prepared by deposition of cobalt nanoislands on Cu(111). Hence, the effect on the electronic structures of C60 from the bimetallic substrate can be compared with that from the Cu(111) step edge. UHV-LT-STM/STS (ultrahigh vacuum-low temperature- scanning tunneling microscopy/spectroscopy) was employed to acquire, at the molecular level, STM images and STS spectra of C60 lodged at the edges of Cu steps and Co nanoislands on Cu(111). Topographic images for the former suggested an orientation of C60 with the hexagon ring facing Cu(111) and for the latter with a hexagon-pentagon bond resting on Cu(111). The discrepancy manifested the effect of aforementioned lateral interactions on the orientation of C60 adsorption. dI/dV spectra of C60 at Cu(111) step edge exhibited LUMO (lowest unoccupied molecular orbital) splitting, while at the edge of cobalt nanoislands additional splitting at the HOMO (highest occupied molecular orbital) level took place. The splitting involved the coupling of adsorbate states to those of the substrate. Different degrees of p-d hybridizations between C60 and metal atoms on the vertical face of the step are proposed for the disparities of dI/dV peaks.
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