Kazuhiko Kominami

High Temperature Photochemical Hole Burning of Tetrasodium 5,10,15,20-tetra(4-sulfonatophenyl)porphin in Polyvinylalcohol

Persistent spectral holes were burned in a film composed of tetrasodium 5,10,15,20-tetra(4-sulfonatophenyl)porphin and polyvinylalcohol at 20 K–80 K. This is the first observation of a photochemical hole burned above liquid nitrogen temperature. The hole width increased with temperature according to power-law dependence from 20 K to 80 K.

Photochemical hole burning of cationic porphin/saponite intercalation compounds

Abstract Intercalation compounds were synthesized from porphin derivatives with cationic substituents and saponite, which is a poly-crystalline layered silicate. The fomation of the intercalation compounds was comfirmed by X-ray diffractions and elemental analysis. We found that the porphin molecules lay their planar skeleton parallel to the silicate layer. Besides, photochemical holes can be burned at least up to 50 K and the amount of spectral diffusion is smaller in these compounds than in a typical neutral porphin/polymer system.

High-temperature photochemical hole burning

It is shown that photochemical hole burning above liquid nitrogen temperature is a common feature of free-base porphin derivatives with ionic substituents dispersed in polyvinylalcohol. The temperature dependence of the hole width is well represented by a power law between 4.2 K and 120 K. Spectral diffusion is suppressed in polyvinylalcohol as compared with polyimide, which suggests that the microenvironment of the ionic porphin derivatives is more rigid due to hydrogen bonds in the former than in the latter. It is also shown that the chemical modification of phenyl rings does not affect much the spectroscopic features of tetraphenylporphin in the visible energy range, which is confirmed by means of absorption and fluorescence spectroscopy, and fluorescence lifetime measurement.

Photochemical hole burning of porphin-cross-linked polymethylmethacrylate

Abstract We synthesized polymethylmethacrylate (PMMA) cross-linked with a tetraphenylporphin (TPP) derivative with four functional groups. The formation of the cross-linked polymer was confirmed by means of the double detection technique of gel permeation chromatography. The irreversible broadening, or the spectral diffusion, of the photochemical hole burned in this cross-linked PMMA is less than in TPP merely dispersed in PMMA. Moreover, the high molecular weight component of the cross-linked PMMA, in which the cross-linkages are expected to be densely formed, exhibits still less spectral diffusion. From these observations, we conclude that the covalent bonds between the TPP molecule and the host polymer suppress the changes of the microscopic stereostructure in the vicinity of the TPP molecule and decrease its spectral diffusion at low temperatures.