Nanoscale Probing of the Interfacial Properties of Metal-supported Low-dimensional Materials

Low-dimensional materials (LDMs), characterized by their high interface-to-volume ratio and quantum confinement effects, exhibit distinct behavior compared to bulk materials. Pioneering studies have highlighted the crucial role of surface nanostructures in determining the properties of LDMs, underscoring the importance of investigating surface structures and interfacial properties at the nanoscale. Scanning tunneling microscopy (STM), with its atomic resolution, allows for precise probing of the morphology of these nanostructures, while tip-enhanced Raman spectroscopy (TERS) offers insight into localized chemical fingerprints. Together, these techniques open the avenue to probe the localized interfacial properties of LDMs. This thesis focuses on two different LDMs: ultrathin ferrous oxide (FeO) and graphitic carbon nitride (GCN). First, ultrathin FeO was fabricated on Au(111) and its atomic structure was resolved, where the FeO nanoislands exhibit two types of edges with distinct metal affinities, enabling selective decoration at the edges of FeO. Second, I evaluated the structure and properties of ultrathin FeO on Au(111), Au(100), and Ag(100) surfaces, underscoring the effects of substrate elements, symmetries, and reconstruction structures. Specifically, the nanostructures of FeO are precisely characterized using STM and TERS, demonstrating the effectiveness of these techniques in the detailed nanoscale analysis of LDMs. Last, this thesis demonstrates the analysis of ultrathin GCN, identifying its non-metallic behavior and atomic topography, which sets the ground for probing the single-layer GCN. Overall, I used STM and TERS to achieve the nanoscale probing of the chemical and physical properties of LDMs. The findings demonstrate the influence of localized features such as edges, defects, and substrates on the behavior of LDMs, thereby paving the way for the rational design of LDM-based materials with tailored properties.