Kenji Kawasaki
Hitachi
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Featured researches published by Kenji Kawasaki.
ACS Applied Materials & Interfaces | 2013
Yuzuru Shimazaki; Shuhei Oinaka; Shota Moriko; Kenji Kawasaki; Satoshi Ishii; Masahiko Ogino; Toshio Kubota; Akihiro Miyauchi
The fluidity of the resin for the nanoimprint lithography was investigated in a quasi-2D space by the shear resonance measurement, which enables us to measure the viscous property of the resin confined in a nanometer gap between mica surfaces. With this technique, we could observe that the resin fluidity was enhanced by the addition of the fluorine-containing monomer. The fluidity of the resin with the fluorine-containing monomer was maintained until the distance between mica surfaces became smaller than 15 nm, wheras the resin without the fluorine-containing monomer started losing its fluidity when the distance became 30 nm. Two reasons possibly explain the result; (i) the interaction between the resin and mica was reduced by the existence of the fluorine-containing segregated layer at the interface, and (ii) the reduction in viscosity took place by the addition of the fluorine-containing monomer that reduced the degree of chain entanglement in the resin because of its small intermolecular interaction force. The effect of the length of the perfluoroalkyl chain in the fluorine-containing monomer is also discussed.
Journal of Physics: Conference Series | 2008
Kazuo Saitoh; Hideaki Yamamoto; Kenji Kawasaki; Yuzo Fukuda; Hideki Tanaka; Michiya Okada; Hitoshi Kitaguchi
Utilizing a cryogenic probe system is a promising approach to improve signal-to-noise-ratio (SNR) in the nuclear magnetic resonance (NMR) spectrometer. We have been developing an NMR spectrometer based on a superconducting-split-pair magnet. This unique structure of the magnet allows using solenoid-shaped antenna coil, which ensures about 2 times higher sensitivity than the conventional saddle-shaped antenna coil. The goal of the present study is to realize higher sensitivity by implementing the superconducting-split-pair magnet and solenoidal-shaped antenna coil. Our immediate objective is to establish the cryogenic probe system for the superconducting-split-pair magnet. In this paper, the basic idea and design of the system and some preliminary results are described.
IEEE Transactions on Applied Superconductivity | 2009
Kenji Kawasaki; Yuzo Fukuda; Mitsuyoshi Tsuchiya; Hiroyuki Yamamoto; Kazuo Saitoh; Hiroyuki Tanaka; Michiya Okada; Hitoshi Kitaguchi
By using a split-pair superconducting magnet with cross-bore, one can implement a solenoidal radio frequency (RF) coil for solution nuclear magnetic resonance (NMR). We expect the solenoidal RF coil to give us higher sensitivity than an ordinary saddle-shaped RF coil. We have developed both room temperature and cryogenic NMR probes with a solenoidal RF coil for a split-pair superconducting magnet. The probes and the solenoidal RF coils were evaluated using a sensitivity test with standard 0.1% ethylbenzene. The sensitivity tests of the room temperature probes indicated that the signal-to-noise ratio (SNR) of the solenoidal RF coil was higher than that of an ordinary saddle-shaped RF coil. In the sensitivity test of the cryogenic probe, we compared a four-turn solenoidal RF coil with a two-turn one. As a result, the SNR of the one of two-turn RF coil was higher than that of the one of the four-turn one. It is believed that the reason is that the SNR depends on the quality factor of the specimen Qs and, furthermore, Qs depends on the shape of the RF coil.
Langmuir | 2018
Shunya Ito; Motohiro Kasuya; Kenji Kawasaki; Ryuta Washiya; Yuzuru Shimazaki; Akihiro Miyauchi; Kazue Kurihara; Masaru Nakagawa
In UV nanoimprinting, the selection of monomers suitable for sub-15 nm patterning is difficult because the filling behavior of resin at this scale still remains scientifically unclear. We demonstrate sub-15 nm patterning by UV nanoimprinting using silica molds with 20, 15, and 7 nm diameter holes; however, the 7 nm diameter pillar patterns were not fabricated using hydroxy-containing monomers. The filling behavior into silica holes of around 10 nm depended on the chemical structure of the monomers. Resonance shear measurements revealed the following: (1) The viscosities of hydroxy-containing monomers confined between chlorodimethyl(3,3,3-trifluoropropyl)silane (FAS3-Cl)-modified surfaces began to increase at distances shorter than those of the monomers between unmodified surfaces. (2) The monomers confined between tridecafluoro-1,1,2,2-tetrahydrooctyltrimethoxysilane-modified surfaces were squeezed out when the surface-surface distance decreased at less than 7 nm. The measured viscosities between the FAS3-Cl-modified silica surfaces were correlated with the insufficient filling behavior into the silica holes of around 10 nm in UV nanoimprinting. Contact angle measurements provided an additional insight that a higher wettability of the monomers onto the antisticking chemisorbed monolayers resulted in imprinted patterns with higher aspect ratios. Considering the increase in the monomer viscosity in the nanospace and the wettability of monomers onto chemisorbed monolayers, we concluded that the monomer showing low viscosity under confinement and high wettability onto the mold surface was suitable for single-digit nanometer UV nanoimprinting.
Archive | 1997
Atsushi Murase; Tetsuo Tanaka; Motoaki Satoyama; Toshiaki Kohno; Kenji Kawasaki; Yoshiaki Morimoto; Akira Tanaka
Journal of Physical Chemistry C | 2014
Tasuku Onodera; Kenji Kawasaki; Takayuki Nakakawaji; Yuji Higuchi; Nobuki Ozawa; Kazue Kurihara; Momoji Kubo
Journal of Physical Chemistry C | 2014
Tasuku Onodera; Kenji Kawasaki; Takayuki Nakakawaji; Yuji Higuchi; Nobuki Ozawa; Kazue Kurihara; Momoji Kubo
Archive | 2001
Kenji Kawasaki; Tetsuo Tanaka; Yoshiaki Morimoto; Kunihisa Nitta; Kimio Tanaka
Archive | 2004
Kenji Kawasaki; Susumu Matsui; 健治 川崎; 進 松井
Archive | 1996
Kenji Kawasaki; Tetsuo Tanaka; Yoshiaki Morimoto; Kunihisa Nitta; Kimio Tanaka