Nobukazu Miyagawa

Mechanistic investigations of the photosensitized reactions of iron arene complexes

Abstract The decomposition of cyclopentadienyliron(II) cumene hexafluorophosphate ([CpFe(Cum)]PF 6 ) was investigated by singlet and triplet sensitization. [CpFe(Cum)]PF 6 quenched the excited state of various sensitizers, and decomposition of [CpFe(Cum)]PF 6 efficiently took place in CH 2 Cl 2 . The quenching rate constants of fluorescence or TT absorption of the sensitizers by [CpFe(Cum)]PF 6 were close to the diffusion rate constants. The rate constants were independent of the exo- or endo-thermicity of the photoinduced electron transfer process assumed to take place. However, they were dependent on the singlet and triplet excitation energies of [CpFe(Cum)]PF 6 and the sensitizers. Thus, the major quenching process would be the singlet and triplet energy transfer. In the case of using 3,3′-carbonyl- bis (7-diethylaminocoumarin) (KC-DA) as a visible-light-sensitizer, the decomposition of [CpFe(Cum)]PF 6 is inefficient, and a photochemically unstable intermediate was generated.

Performance of vinyl ether cross-linkers on resist for 193-nm lithography

A three-component positive working resist composed of an acrylate polymer, vinyl ether cross-linker, and photoacid generator was evaluated for vacuum UV lithography. The vinyl ether cross-linker using tricyclodecyl group of alicyclic compound has a high transparency. This resist system shows a relatively high sensitivity and has a good profiling by irradiation using 193 nm light from an ArF excimer laser. Moreover, we found that these cross-linking type resists have advantages with respect to its resist properties such as the acid diffusion and the dry etching resistance.

Unexpected and unusual triboelectrification behavior of polymer films containing carboxyl group.

The triboelectrification behavior of polymer films when in contact with iron carrier beads was investigated using a homemade special instrument which can control relative humidity under a nitrogen atmosphere. The films showed a large humidity-dependent charging behavior; the charge amount increases with the ambient humidity in the range of a few percent RH to ca. 60% RH. This dependence is explained in terms of the model based on the water charging during the friction and the penetration of the positively charged water into the film. However, it was found that the humidity dependence is significantly depressed by the doping of carboxylic acids into the film or by the introduction of a carboxyl group in the polymer backbone. This depression is again explained by the above charged-water penetration model in which carboxylate ions trap the positively charged water on the film surface.

Water‐dispersible microgel modified with methacryloyl groups by ionic bonding on the surface and the photopolymer microgel

A novel water-dispersible reactive microgel, which had a diameter of 40–90 nm, was synthesized for photopolymer materials. The microgels have segments with substituted ammonium groups, to provide water solubility, in their polymer networked structure. It has unsaturated groups connected to the quaternary nitrogens by ionic bonding (I-type microgel). The I-type microgel was compared with one that has methacryloyl groups connected with the quaternary nitrogens of the microgel by covalent bonding (C-type microgel). The I-type microgels were able to separately control the modified amount of quaternary nitrogen and methacryloyl group. In the presence of 2,4-diethylthioxantone as a photoinitiator and pentaerthritol triacrylate as a crosslinker, the photopolymer containing the C-type or I-type microgels had sensitivity high enough for practical use. Not only the amount of the methacryloyl group of the microgel but the amount of the quaternary nitrogen affected the sensitivity and the rate of polymerization of the water-dispersible photopolymer containing the I-type microgels. Copyright