| 초록 |
Electronic structures of carbon allotrope such as amorphous carbon, graphene, graphite, carbon nano tube, diamond and carbon nitride (C3N4) and silicon carbide (SiC) are investigated by transmisison electrron microsocpy (TEM), electron energy loss spectroscopy (EELS) and density functional theory (DFT) calculation. Atomic number 6 of carbon has 2 core electrons and 4 valence electrons. In the four-fold coordinated structure such as diamond and SiC, they show only σ* bonding structure (tetrahedrally directed sp3 configuration). In the three-fold structure, strong sp2 configuration and one weak bonding such as graphite and C3N4, they show both π* and σ* boning structure. In this presentation, we demonstrate the defective single layer graphene by HRTEM, diffraction and EELS analysis. It shows 3 eV pre-peak prior to the π* bonding in the defective single layered grapheme structure which is consistent with the graphene edge structure obtained by early researcher. We will also discuss specimen preparation for observing cross-sections of 2D materials. |
