Spectroscopic Studies on Layered Materials

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This project is supported by the Electronic and Photonic Materials Program (EPM) and Condensed Matter Physics Program (CMP), both in the Division of Materials Research (DMR).Nontechnical Description: This research project aims to significantly expand the knowledge on important topics in a nanoscience research field, including nanocarbon materials, transition-metal dichalcogenides in the form of ultrathin layers with thicknesses of only a few atomic layers, and the newly discovered few-layered phosphorus material called phosphorene, which has a novel layered crystal structure and promising electronic, optical, and spectroscopic properties. The research results are published in major scientific journals and presented at national and interternatinal scientific conferences by the principal investigator and participating students and postdoctoral researchers, thereby providing valuable educational experiences for them. In addition, the principal investigator gives colloquia at universities and invited talks in scientific conferences, furthering the nanoscience research field.Technical Description: The project is on a comprehensive and comparative study of nanocarbons, graphene, transition metal dichalcogenides, and phosphorene. Raman spectroscopy is the main experimental method. The graphene research studies take advantage of the large present knowledge base of the electronic properties of graphene to study new aspects of Raman resonance windows, twist angle phenomena, and electron-phonon interaction phenomena. These studies also can be best carried out in graphene because of its special properties, such as the large isotope effect provided by the carbon 12 and 13 isotopes, which is advantageous for studying electron-phonon interactions quantitatively. Similarly, the role of substrate effects in enhancing Raman spectroscopy signals and symmetry-breaking phenomena produced by external perturbations have been extensively studied in graphene, which now can be used for metrological purposes. In this context, similar physical properties can now be studied productively in few-layer transition metal dichalcogenides and phosphorene individually and on a comparative basis.