Teruo Yagishita

Holographic Recording Material Containing Poly-N-vinylcarbazole

A volume phase holographic recording material with high diffraction efficiency and high durability against humidity has been developed. The holographic material consists of Poly-N-vinylcarbazole (PVCz) as a base polymer, camphorquinone as an initiator and thioflavine-T as a sensitizer. This film is sensitive to argon ion laser light, and exposure energy of 500 mJ/cm2 is required to realize high diffraction efficiency. After recording a latent image of a fringe pattern by exposure, a hologram was developed by swelling and shrinking of the film with two sorts of solvent. The thickness of the hologram could be reduced to 2.5 μm, because the PVCz hologram has a large amplitude of the refractive index modulation related with the crystallinity modulation. The high diffraction efficiency coupled with the thin layer made an incident light angle wide enough to maintain a high diffraction efficiency around the Bragg angle.

Interface study of Nb/ZrOx‐Zr/Nb Josephson junctions

We studied the interfaces in Nb/ZrOx‐Zr/Nb and Nb/AlOx‐Al/Nb Josephson junctions using secondary ion mass spectrometry. An adsorbed water vapor layer, which has detached from the chamber wall, exists at the interface of the Nb/AlOx‐Al/Nb junctions. This layer does not exist at the interface of the Nb/ZrOx‐Zr/Nb junctions. We also find an argon sputtering gas is absorbed in the ZrOx‐Zr layer as much as in Nb layers, but not at all in the AlOx‐Al layer. The adsorbed water vapor layer acts as a weak barrier for grain boundary diffusion in the Nb/AlOx‐Al/Nb structure. In the Nb/ZrOx‐Zr/Nb structure, we believe the adsorbed water vapor layer was sputter‐etched during the Zr deposition, the high melting point of Zr contributes to the stability of the junction interface.

Photoconduction of Copper Phthalocyanine-Binder Photoconductor Sensitized with Poly-N-vinylcarbazole

A nontoxic organic photoconductor for near infrared light has been developed. It consists of poly-N-vinylcarbazole (PVCz) dispersed in a copper phthalocyanine (CuPc)-binder resin system. PVCz has been selected from among several electron donating compounds that are considered to be able to reduce the induction period (TN) that is a typical imperfection of the binary system. The optimum mixing ratio of the three components (CuPc, PVCz, and a binder resin) was determined after examining film-forming ability, charge acceptance, and exposure energy for half-decay of the surface potential (E1/2). The photoconductor, composed of E-crystal form of CuPc (40 wt/%), PVCz (10 wt/%), and a polyester binder resin (50 wt/%), has an E1/2 of 3.2 , ¿J/cm2 at a light of 760 nm. It has a charge acceptance of 800 V, in accordance with the p-type. conduction of CuPc, when a positive surface charge is used.