|Budget Amount *help
¥2,600,000 (Direct Cost : ¥2,600,000)
Fiscal Year 1998 : ¥900,000 (Direct Cost : ¥900,000)
Fiscal Year 1997 : ¥1,700,000 (Direct Cost : ¥1,700,000)
The target of the optical recording system with high density is now focused on systems based on a GaInPAl laser diode of 635 nm. This system achieves 1.5 times higher recording density in comparison with the present system of 780 nm and is therefore expected as an ideal system for DVD.The purpose of our investigation is to explore or synthesize functional dyestuffs that can switch the absorption band around 635 nm. In the present investigation, perylene pigments as well as non-benzenoid compounds such as 8,8-dicyanoheptafulvenes have been investigated. Among perylene pigments, we found a black perylene which exhibits a vivid red color in an amorphous state but turns black (appearance of the absorption band around 635 nm) when crystallized. The electronic structure has therefore been characterized extensively on the basis of the crystal structure, polarized reflection spectra as well as MO calculations. In parallel, we have tested a number of optical disks based on the black perylene and confirmed good recording characteristics. As for 8,8-dicyanoheptafulvene derivatives, we have newly prepared a variety of derivatives, one of which showed an optical switching around 635 nm on going from an amorphous state to the crystallized state. This compound has also attracted attention for optical recording systems, but we soon found that the amorphous phase crystallizes rapidly in the ambient atmosphere. For this reason, we were obliged to abandon the application of this material for optical disks. However, unexpectedly, the present compound was found to exhibit non-linear optical characteristics, and a patent for this application has been claimed.