Estimating band gap of amorphous diamond and nanocrystalline diamond powder by electron energy loss spectroscopy

Electronic properties such as band gap and density of states were estimated by electron energy loss spectroscopy for amorphous diamond synthesized from C₆₀ fullerene by shock compression. The imaginary part of the dielectric function, ε₂, obtained showed that the magnitude of the gap was 3.5 to 4.5 eV, a little smaller than that of crystalline diamond (5.5 eV), and that excitation of interband transition was not observed at X and L points but only at F points. The density of states around the gap was rather broad. These characteristic electronic properties observed can be explained by the unique atomic configuration of this material examined by radial distribution function (RDF) analysis.