Takashi Hashida

Controls of photochromic reactions in spiropyran Langmuir-Blodgett films☆

The possibility of controlling photochromic reactions has been investigated in Langmuir-Blodgett (LB) films. The formation of J aggregates of a spiropyran (SP1822) with two long chains has been found previously. We have studied another possibility using LB films of 1′-octadecyl-3′,3′-dimethyl-6-nitro-8-methoxy- spiro[2H-1-benzopyran-2,2′-indoline] (SP1801). SP1801 at the air-water interface gave a monolayer which showed the photomerocyanine form. The LB film of the compound returned to the spiropyran form in the dark. The LB film of the hetero structure with SP1801 and stearic acid, however, turned to J aggregates from the photomerocyanine form spontaneously in the dark. The absorption of the J aggregates was a sharp and intense band, and the half-decay period in the dark was 104 times longer than that of conventional spiropyrans. SP1801, in addition to SP1822, is suggested as a candidate for a multifrequency optical memory system with several J-aggregated photochromic compounds having different sharp absorption bands.

Multiple Optical Memory using Photochromic Spiropyran Aggregates

Abstract Multiple recording technology is particularly important for the high density optical memory. Through investigating the aggregate—forming ability of the new photochromic spiropyrans, we have developed five novel spiropyrans, the aggregates of which have sharp absorption bands at different wavelengths. We have fabricated a recording medium stacked with the five kinds of aggregate layers and confirmed ten multiple optical recording characteristics by combining the five multiple frequency recording with the recording by two mutually perpendicular linear—polarized lights.

Development of High-Sensitivity Ultrasonic Transducer in Air with Nanofoam Material

For a high-sensitivity ultrasonic transducer in air, it was considered that nanofoam be applied to its acoustic matching layer. Nanofoam is a porous material that is made by the sol-gel process. Since nanofoam has an extremely low acoustic impedance, it is effective for the acoustic matching layer of an ultrasonic transducer in air. In this study, we have fabricated an ultrasonic transducer that had two acoustic matching layers and estimated its acoustic properties. The two matching layers were made of silica nanofoam and porous ceramic. The sensitivity of the developed ultrasonic transducer was about twenty times higher than that of a conventional ultrasonic transducer in air.

Spiropyran Aggregates for Multiple Optical Memory

Abstract Investigating the aggregate-forming ability of the new synthesized photochromic spiropyrans, we have developed novel five spiropyran aggregates each of which has a sharp absorption band at different wavelength. We have fabricated a recording medium stacked with the aggregate layers, and confirmed 10-multiple optical memory by means of combining the multi-frequency recording with the recording by two mutually perpendicular linear-polarized lights.