The π–π* electronic absorption spectra of 1-amino-, 1,4-diamino-, and 1,4,5,8-tetraaminoanthraquinones were investigated by means of the polarized absorption spectra using stretched PVA sheets and theoretical calculations. Each of these compounds has four absorption bands in the near-ultraviolet region (210–340 nm) and one in the visible region. The bands of the aminoanthraquinones which appear in the visible region can be assigned to the intramolecular charge-transfer transitions associated with the charge migration from the ami no group to the carbonyl groups.
The electronic structure of graphite is studied using the generalized tight-binding approximation. We investigate how the energy spectra around the Fermi energy of graphite depend on interlayer stacking arrangement. We find that graphite and bilayer graphene with rotational stacking arrangement are metals with a massless Dirac fermion at the Fermi level, as is the case for isolated graphene sheets. Due to the spatially separated K points on each layer, two pairs of linear dispersion curves cross at the Fermi energy and are expected to exhibit characteristics different from those of graphite with AB stacking. #
The optical disc with larger capacity and higher speed data recording rate will be required in coming broadband network society. We have developed the inorganic write-once disc with quadruple recording layers for the blu-ray disc system. We obtained the reflectivity of more than 5 % and a jitter value of less than 10% for each recording layer. As a result, we proved the possibility of 100 GB user capacity of 120 mm diameter size.
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