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Papers by Hirosato Monobe
The Japan Society of Applied Physics, 2016
1.はじめに 電気泳動堆積法は、バインダーを用いるこ となく、基材に微粒子を担持することができる。 そのため、光触媒のように基材への担持にバイ ンダーを用いることで活性が低下するような 材料の固... more 1.はじめに 電気泳動堆積法は、バインダーを用いるこ となく、基材に微粒子を担持することができる。 そのため、光触媒のように基材への担持にバイ ンダーを用いることで活性が低下するような 材料の固定化に適した方法である。また、導電 性を有する基材であれば、そのサイズや形状に 制約がないという利点がある。 例えば、光触媒の代表的な材料である TiO2 は赤外光(2.5 μm~11.7 μm)の透過率に優れ、 高い屈折率(2.4 以上)を有する。従って、TiO2 から作製される線状パターンに赤外光を入射 した場合、赤外光はパターン通りに伝達するこ とから、線状パターンは赤外光の導波路となる。 そこで、電気泳動堆積法により TiO2微粒子 からマイクロパターンを作製し、得られたパタ ーンの一端から入射した赤外レーザ光のアセ トアルデヒドガス[CH3CHO(g)]暴露前後での 出射光量の変化を検出することで、TiO2微粒子 の光触媒活性を評価した結果について報告す る。 2.実験方法 (1)TiO2マイクロパターンの作製 ガラス基板上に、Ti 膜(100 nm)の蒸着、 フォトリソグラフィによるレジストパターン の作製、エッチングによる不必要な Ti 膜の除 去を行うことで、Ti のマイクロパターンを作 製した。この Ti マイクロパターン上に、電気 泳動堆積法により、TiO2微粒子を堆積させTiO2 マイクロパターンを得た。 (2)赤外レーザ光による光触媒活性の評価 図 1 のように、石英管と BaF2円板で構成さ れる評価容器内に TiO2 マイクロパターンを封 入した。次に、CH3CHO(g)を注入し、TiO2マイ クロパターン内部を透過する赤外レーザ (10.69 μm)光量をパワーメータで検出した。 なお、同様の実験を紫外光照射下でも行った。 3.結果と考察 電気泳動堆積法を用いることで、バインダー を用いることなく、TiO2微粒子のみから幅 100 〜500 μm、厚さ 100 μm のマイクロパターンを 得た。 得られた TiO2 マイクロパターンについて、 CH3CHO(g)への暴露前後における出射赤外レ ーザ光の強度変化の測定結果を図 2 に示す。図 2 から、紫外光照射の有無にかかわらず、 CH3CHO(g)を注入するとパターンに吸着され た CH3...
Extended Abstracts of the 2008 International Conference on Solid State Devices and Materials, 2008
Molecular Crystals and Liquid Crystals, 2017
In the present study, a LC semiconductor, 2-dodecyl-7-(4-fluorophenyl)-[1] benzothieno[3,2-b][1]b... more In the present study, a LC semiconductor, 2-dodecyl-7-(4-fluorophenyl)-[1] benzothieno[3,2-b][1]benzothiophene (FPh-BTBT-C12) was studied on charge carrier mobility correlated to the mesomorphism. The introduction of a fluorophenyl group on alkyl-BTBT core part leads the higher thermal stability of the mesophase. The observed drift carrier mobility of hole is 0.07 cm 2 V −1 s −1 in the lower temperature smectic mesophase by time-of-flight technique. We used FPh-BTBT-C12 solutions (e.g. 0.1 wt% in p-xylene) for forming an organic semiconductor layer by solution casting, and fabricated top-contact/bottom-gate type filed effect transistor devices and its mobility was determined 0.42 cm 2 V −1 s −1 at room temperature.
Ultramicroscopy, 1998
We previously developed a scanning near-field optical microscope (SNOM) for fluorescence microsco... more We previously developed a scanning near-field optical microscope (SNOM) for fluorescence microscopy and fluorescence spectroscopy by combining SNOM and atomic force microscope (AFM). In this combined microscope, a bent optical fiber with a sharpened tip end was used for simultaneous SNOM and AFM recording. In the present work, we used slim optical fiber probes with a diameter of 40μm produced
Molecular Crystals and Liquid Crystals, 2003
ABSTRACT
Liquid Crystals, 2013
Substitution of each phenyl in 1,3,5-triphenyl-6-oxoverdazyl with three alkoxy groups induces an ... more Substitution of each phenyl in 1,3,5-triphenyl-6-oxoverdazyl with three alkoxy groups induces an ordered columnar hexagonal phase (Colh(o)) below 130°C in 1b[n], while in the alkylsulfanyl analogues 1a[n] additional periodicity along the columns was found rendering the phase a true three-dimensional columnar hexagonal phase (Colh(3D)) below 60°C. Both series exhibit broad absorption bands in the visible region with maxima at 540 and 610 nm in series 1a[n] and at 486 and 614 nm in series 1b[n]. Unusual reversible thermochromism is observed in series 1b[n], in which the dark green isotropic phase turns red in the discotic phase. Analysis of 1a[8] revealed redox potentials E0/+11/2 = +0.99 V and E0/ −11/2 = –0.45 V vs. saturated calomel electrode (SCE), while the potentials in the alkoxy analogue 1b[8] are shifted cathodically by 0.16 V. Photovoltaic studies of 1a[8] demonstrated hole mobility of μh = 1.52 × 10−3 cm2 V−1 s−1 in the mesophase with an activation energy Ea = 0.06 ± 0.01 eV. Magnetisation studies of 1a[8] revealed nearly ideal paramagnetic behaviour in either the solid or fluid phase above 200 K and weak antiferromagnetic interactions at low temperatures. In contrast, a noticeable drop of about 4% in μeff was observed during the I→Col phase transition in 1b[8], which coincide with the thermochromic effect.
Chemistry Letters, 2003
ABSTRACT
Journal of Materials Chemistry, 2001
The lamello-columnar mesophase of a [1] benzothieno [3, 2-b][1] benzothiophene-2, 7-dicarboxylate... more The lamello-columnar mesophase of a [1] benzothieno [3, 2-b][1] benzothiophene-2, 7-dicarboxylate (BTBT) derivative has been investigated by means of X-rays on an aligned sample. The most probable model of molecular organisation corresponds to an assembly ...
Chemistry – An Asian Journal
European Journal of Organic Chemistry
Japanese Journal of Applied Physics
Journal of Materials Chemistry C
Benzothienobenzothiophene (BTBT) liquid-crystalline semiconductors are arousing a lot of interest... more Benzothienobenzothiophene (BTBT) liquid-crystalline semiconductors are arousing a lot of interest due to their long-range ordered, self-organizational abilities and high-charge carrier transport properties.
Chemistry – An Asian Journal
J. Mater. Chem. C
Searching for new organic, mesomorphic semiconductors is essential for the development of applica... more Searching for new organic, mesomorphic semiconductors is essential for the development of applications in the emerging field of molecular electronics.
Optics Laser Technology, Jul 29, 1994
Fibre probes for photon scanning tunnelling microscope (PSTM) have been fabricated by selective c... more Fibre probes for photon scanning tunnelling microscope (PSTM) have been fabricated by selective chemical etching. We succeeded in fabricating a fibre probe with tip curvature radius of less than 3 nm and cone angle 0 = 14" by utilizing a fibre with a relative refractive-index difference between cladding and core of 2.9%. The high reproducibility of this technique is also demonstrated by obtaining a cone angle, and height differences between two cores of a dual-core fibre, of less than 0.2" and 20nm respectively. To avoid the collision between the cladding part of the fibre probe and under observation of the sample caused by the probe diameter, which is much larger than the wavelength of the fibre probe tip, a two-step etching method was applied to reduce the cladding diameter while the cone angle kept constant. Furthermore, to reduce the surrounding light noise, the fibre probe was metal coated, and the relation between coating thickness and the transmitted power was investigated.
Journal of Fluorine Chemistry, Aug 1, 2006
The alignment behavior of the triphenylene compounds possessing fluoroalkylated side chains was i... more The alignment behavior of the triphenylene compounds possessing fluoroalkylated side chains was investigated for the hexagonal columnar (Colh) mesophase on the polyimide-, cetyltrimethylammonium bromide (CTAB)-, and indium-SnO2 (ITO)-coated glass substrates by polarizing optical microscopy. It was found that 2,3,6,7,10,11-hexakis(1H,1H,2H,2H,3H,3H-perfluoroheptyloxy)- and 2,3,6,7,10,11-hexakis(1H,1H,2H,2H,3H,3H-perfluorononyloxy)-triphenylenes exhibit a spontaneous homeotropic alignment on these substrates, in contrast to the non-uniformity of alignment of Colh phase in
MRS Proceedings, 1999
ABSTRACTPhotoconductivity of a mesogenic tetraphenylporphyrin (TPP) is shown in relation to the m... more ABSTRACTPhotoconductivity of a mesogenic tetraphenylporphyrin (TPP) is shown in relation to the mesomorphic phase transition behavior. The TPP mesogen shows two types of mesophases having smectic-like order (lamellar mesophases : DL and DLC phases named in this work) and the photocurrent changes stepwise at the phase transitions with non-Arrhenius dependence whilst the darkcurrent tends to be Arrhenius. The hole mobility was measured for the random domain cell and was found to be faster than 10−4 cm2v−1sec−1 in the mesophases. The cell used for the photocurrent measurements was a sandwich-type one using two ITO glass slides as electrtodes and show rectification behavior for the crystal and the low-temperature mesophase (DLC) in contrast to non-rectification of photocurrent in the high-temperature mesophase (DL). These properties of charge carrier migration as an electronic process are profoundly related to molecular order as well as molecular motions in mesophase.
The Japan Society of Applied Physics, 2016
1.はじめに 電気泳動堆積法は、バインダーを用いるこ となく、基材に微粒子を担持することができる。 そのため、光触媒のように基材への担持にバイ ンダーを用いることで活性が低下するような 材料の固... more 1.はじめに 電気泳動堆積法は、バインダーを用いるこ となく、基材に微粒子を担持することができる。 そのため、光触媒のように基材への担持にバイ ンダーを用いることで活性が低下するような 材料の固定化に適した方法である。また、導電 性を有する基材であれば、そのサイズや形状に 制約がないという利点がある。 例えば、光触媒の代表的な材料である TiO2 は赤外光(2.5 μm~11.7 μm)の透過率に優れ、 高い屈折率(2.4 以上)を有する。従って、TiO2 から作製される線状パターンに赤外光を入射 した場合、赤外光はパターン通りに伝達するこ とから、線状パターンは赤外光の導波路となる。 そこで、電気泳動堆積法により TiO2微粒子 からマイクロパターンを作製し、得られたパタ ーンの一端から入射した赤外レーザ光のアセ トアルデヒドガス[CH3CHO(g)]暴露前後での 出射光量の変化を検出することで、TiO2微粒子 の光触媒活性を評価した結果について報告す る。 2.実験方法 (1)TiO2マイクロパターンの作製 ガラス基板上に、Ti 膜(100 nm)の蒸着、 フォトリソグラフィによるレジストパターン の作製、エッチングによる不必要な Ti 膜の除 去を行うことで、Ti のマイクロパターンを作 製した。この Ti マイクロパターン上に、電気 泳動堆積法により、TiO2微粒子を堆積させTiO2 マイクロパターンを得た。 (2)赤外レーザ光による光触媒活性の評価 図 1 のように、石英管と BaF2円板で構成さ れる評価容器内に TiO2 マイクロパターンを封 入した。次に、CH3CHO(g)を注入し、TiO2マイ クロパターン内部を透過する赤外レーザ (10.69 μm)光量をパワーメータで検出した。 なお、同様の実験を紫外光照射下でも行った。 3.結果と考察 電気泳動堆積法を用いることで、バインダー を用いることなく、TiO2微粒子のみから幅 100 〜500 μm、厚さ 100 μm のマイクロパターンを 得た。 得られた TiO2 マイクロパターンについて、 CH3CHO(g)への暴露前後における出射赤外レ ーザ光の強度変化の測定結果を図 2 に示す。図 2 から、紫外光照射の有無にかかわらず、 CH3CHO(g)を注入するとパターンに吸着され た CH3...
Extended Abstracts of the 2008 International Conference on Solid State Devices and Materials, 2008
Molecular Crystals and Liquid Crystals, 2017
In the present study, a LC semiconductor, 2-dodecyl-7-(4-fluorophenyl)-[1] benzothieno[3,2-b][1]b... more In the present study, a LC semiconductor, 2-dodecyl-7-(4-fluorophenyl)-[1] benzothieno[3,2-b][1]benzothiophene (FPh-BTBT-C12) was studied on charge carrier mobility correlated to the mesomorphism. The introduction of a fluorophenyl group on alkyl-BTBT core part leads the higher thermal stability of the mesophase. The observed drift carrier mobility of hole is 0.07 cm 2 V −1 s −1 in the lower temperature smectic mesophase by time-of-flight technique. We used FPh-BTBT-C12 solutions (e.g. 0.1 wt% in p-xylene) for forming an organic semiconductor layer by solution casting, and fabricated top-contact/bottom-gate type filed effect transistor devices and its mobility was determined 0.42 cm 2 V −1 s −1 at room temperature.
Ultramicroscopy, 1998
We previously developed a scanning near-field optical microscope (SNOM) for fluorescence microsco... more We previously developed a scanning near-field optical microscope (SNOM) for fluorescence microscopy and fluorescence spectroscopy by combining SNOM and atomic force microscope (AFM). In this combined microscope, a bent optical fiber with a sharpened tip end was used for simultaneous SNOM and AFM recording. In the present work, we used slim optical fiber probes with a diameter of 40μm produced
Molecular Crystals and Liquid Crystals, 2003
ABSTRACT
Liquid Crystals, 2013
Substitution of each phenyl in 1,3,5-triphenyl-6-oxoverdazyl with three alkoxy groups induces an ... more Substitution of each phenyl in 1,3,5-triphenyl-6-oxoverdazyl with three alkoxy groups induces an ordered columnar hexagonal phase (Colh(o)) below 130°C in 1b[n], while in the alkylsulfanyl analogues 1a[n] additional periodicity along the columns was found rendering the phase a true three-dimensional columnar hexagonal phase (Colh(3D)) below 60°C. Both series exhibit broad absorption bands in the visible region with maxima at 540 and 610 nm in series 1a[n] and at 486 and 614 nm in series 1b[n]. Unusual reversible thermochromism is observed in series 1b[n], in which the dark green isotropic phase turns red in the discotic phase. Analysis of 1a[8] revealed redox potentials E0/+11/2 = +0.99 V and E0/ −11/2 = –0.45 V vs. saturated calomel electrode (SCE), while the potentials in the alkoxy analogue 1b[8] are shifted cathodically by 0.16 V. Photovoltaic studies of 1a[8] demonstrated hole mobility of μh = 1.52 × 10−3 cm2 V−1 s−1 in the mesophase with an activation energy Ea = 0.06 ± 0.01 eV. Magnetisation studies of 1a[8] revealed nearly ideal paramagnetic behaviour in either the solid or fluid phase above 200 K and weak antiferromagnetic interactions at low temperatures. In contrast, a noticeable drop of about 4% in μeff was observed during the I→Col phase transition in 1b[8], which coincide with the thermochromic effect.
Chemistry Letters, 2003
ABSTRACT
Journal of Materials Chemistry, 2001
The lamello-columnar mesophase of a [1] benzothieno [3, 2-b][1] benzothiophene-2, 7-dicarboxylate... more The lamello-columnar mesophase of a [1] benzothieno [3, 2-b][1] benzothiophene-2, 7-dicarboxylate (BTBT) derivative has been investigated by means of X-rays on an aligned sample. The most probable model of molecular organisation corresponds to an assembly ...
Chemistry – An Asian Journal
European Journal of Organic Chemistry
Japanese Journal of Applied Physics
Journal of Materials Chemistry C
Benzothienobenzothiophene (BTBT) liquid-crystalline semiconductors are arousing a lot of interest... more Benzothienobenzothiophene (BTBT) liquid-crystalline semiconductors are arousing a lot of interest due to their long-range ordered, self-organizational abilities and high-charge carrier transport properties.
Chemistry – An Asian Journal
J. Mater. Chem. C
Searching for new organic, mesomorphic semiconductors is essential for the development of applica... more Searching for new organic, mesomorphic semiconductors is essential for the development of applications in the emerging field of molecular electronics.
Optics Laser Technology, Jul 29, 1994
Fibre probes for photon scanning tunnelling microscope (PSTM) have been fabricated by selective c... more Fibre probes for photon scanning tunnelling microscope (PSTM) have been fabricated by selective chemical etching. We succeeded in fabricating a fibre probe with tip curvature radius of less than 3 nm and cone angle 0 = 14" by utilizing a fibre with a relative refractive-index difference between cladding and core of 2.9%. The high reproducibility of this technique is also demonstrated by obtaining a cone angle, and height differences between two cores of a dual-core fibre, of less than 0.2" and 20nm respectively. To avoid the collision between the cladding part of the fibre probe and under observation of the sample caused by the probe diameter, which is much larger than the wavelength of the fibre probe tip, a two-step etching method was applied to reduce the cladding diameter while the cone angle kept constant. Furthermore, to reduce the surrounding light noise, the fibre probe was metal coated, and the relation between coating thickness and the transmitted power was investigated.
Journal of Fluorine Chemistry, Aug 1, 2006
The alignment behavior of the triphenylene compounds possessing fluoroalkylated side chains was i... more The alignment behavior of the triphenylene compounds possessing fluoroalkylated side chains was investigated for the hexagonal columnar (Colh) mesophase on the polyimide-, cetyltrimethylammonium bromide (CTAB)-, and indium-SnO2 (ITO)-coated glass substrates by polarizing optical microscopy. It was found that 2,3,6,7,10,11-hexakis(1H,1H,2H,2H,3H,3H-perfluoroheptyloxy)- and 2,3,6,7,10,11-hexakis(1H,1H,2H,2H,3H,3H-perfluorononyloxy)-triphenylenes exhibit a spontaneous homeotropic alignment on these substrates, in contrast to the non-uniformity of alignment of Colh phase in
MRS Proceedings, 1999
ABSTRACTPhotoconductivity of a mesogenic tetraphenylporphyrin (TPP) is shown in relation to the m... more ABSTRACTPhotoconductivity of a mesogenic tetraphenylporphyrin (TPP) is shown in relation to the mesomorphic phase transition behavior. The TPP mesogen shows two types of mesophases having smectic-like order (lamellar mesophases : DL and DLC phases named in this work) and the photocurrent changes stepwise at the phase transitions with non-Arrhenius dependence whilst the darkcurrent tends to be Arrhenius. The hole mobility was measured for the random domain cell and was found to be faster than 10−4 cm2v−1sec−1 in the mesophases. The cell used for the photocurrent measurements was a sandwich-type one using two ITO glass slides as electrtodes and show rectification behavior for the crystal and the low-temperature mesophase (DLC) in contrast to non-rectification of photocurrent in the high-temperature mesophase (DL). These properties of charge carrier migration as an electronic process are profoundly related to molecular order as well as molecular motions in mesophase.