Updated on 2024/07/15

写真a

 
TABE, Yuka
 
Affiliation
Faculty of Science and Engineering, School of Advanced Science and Engineering
Job title
Professor

Professional Memberships

  •  
     
     

    THE PHYSICAL SOCIETY OF JAPAN

  •  
     
     

    THE JAPANESE LIQUID CRYSTAL SOCIETY

Research Areas

  • Biophysics, chemical physics and soft matter physics

Research Interests

  • Langmuir monolayers

  • liquid crystals

  • soft matter

 

Papers

  • Steady rigid-body rotation of cholesteric droplets and their dumbbell-shaped aggregates driven by heat flux along the helical axes

    Katsu Nishiyama, Shinji Bono, Yuka Tabe

    SOFT MATTER   17 ( 48 ) 10818 - 10828  2021.12

     View Summary

    We investigated the steady unidirectional rotation of cholesteric (Ch) droplets driven by a heat flux. The droplets coexisted with the isotropic (Iso) phase and possessed a helical molecular arrangement. When a heat flux was transported along the helical axis, the droplets and their dumbbell-shaped aggregates exhibited steady rigid rotation. Our results are in contrast with those of previous reports in which Ch droplets in the same geometry exhibited pure director rotation. The fact that Ch droplets and their aggregates prefer rigid rotation can be ascribed to the orientational elasticity combined with the anchoring force at the Ch-Iso interface, which locks the director to the rotational flow in the droplets.

    DOI

    Scopus

    3
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    (Scopus)
  • Induced smectic phases composed of 5CB and EBBA mixtures: structures and dielectric property

    Shoyo Takei, Mitsuki Fujioka, Yudai Shimada, Yuka Tabe, Takahiro Yamamoto

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS    2021.12

     View Summary

    Induced smectic phases of 5CB-EBBA binary mixtures were investigated with respect to the structures, stabilities, and molecular motion. The highest stability of the ordered smectic phase was obtained when 5CB and EBBA were mixed at 1:2. At the same ratio, the transferred charges between 5CB and EBBA took the maximum, indicating the direct correlation of the induced phase to the charge-transfer interaction. Whereas, the molecular motion monotonically slowed down with increasing EBBA, which is ascribed to the decrease of the free volume. The stability and the slow molecular reorientation may be independently controlled in the induced smectics.

    DOI

    Scopus

  • Free Radical Polymerization in a Confined System: An Analysis Based on a Kinetic Growth Model on Regular Graphs

    Ryosuke Yamamoto, Yuka Tabe

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   90 ( 4 )  2021.04

     View Summary

    With a stochastic model based on self-avoiding walk of multi walkers, free radical polymerization in a confined system is numerically investigated. As a reaction field, we consider not a confined lattice but a graph to represent interactions between polymerizable molecules and possible networks. The result of calculation visualized how the individual polymer chains should grow from moment to moment, which can hardly be tracked by other statistic methods such as Monte Carlo simulation. The calculation also provided the effective chain length of polymers and the average polymerization time, both of which followed a log-normal distribution. With respect to the initial radical density, the effective polymer length monotonically decreased, while the average polymerization time exhibited a single maximum. Considering the probabilities for the multiple radicals to encounter, we derived an inequality that well explained these behaviors. The stochastic model combined with graphs can be a useful tool for analyzing confined polymerization system.

    DOI

    Scopus

  • 2D Photopolymerization of Liquid Crystalline Langmuir Monolayers: In Situ Observation by Reflected Polarizing Microscopy

    Tatsuhiko Ishigami, Yutaka Inake, Yuka Tabe, Yuki Nonaka, Koichi Endo, Isa Nishiyama

    Langmuir   36 ( 30 ) 8914 - 8921  2020.08

     View Summary

    Photopolymerization of Langmuir monolayers composed of bifunctional acrylic liquid crystalline (LC) compounds was observed in situ by polarizing optical microscopy. In a dark state, monolayers of the LC compounds formed at an air-water or liquid-liquid interface exhibited liquid-like fluidity and in-plane optical anisotropy because of the coherent molecular tilt from the surface normal. Irradiated by UV light, the in-plane anisotropy and the liquid fluidity gradually disappeared with time, indicating the formation of the polymerized monolayers. Because the constituent molecules possess polymerizable acryloyl groups, under UV light, they are combined by acrylic polymer chains grown on the interface, which decreases the intermolecular distance and disturbs the coherent molecular tilt, resulting in the evanescence of the in-plane optical anisotropy and the fluidity. In contrast to the classical model of radical polymerization, the time taken for the monolayers to be photopolymerized was inversely proportional to the UV intensity, which is ascribed to the ideal two dimensionality of the reaction field. Because the polymerization degree is quantitatively estimated from the in-plane optical anisotropy of the LC monolayers, the process is traced, from moment to moment, by in situ microscopy observation.

    DOI PubMed

    Scopus

    2
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  • Heat-Driven Rigid-Body Rotation of a Mixture of Cholesteric Liquid Crystal Droplets and Colloids

    Shinji Bono, Yuji Maruyama, Katsu Nishiyama, Yuka Tabe

    JOURNAL OF PHYSICAL CHEMISTRY B   124 ( 28 ) 6170 - 6174  2020.07

     View Summary

    We show that cholesteric (Ch) liquid crystal droplets with cylindrically symmetric orientation dispersing in an isotropic (Iso) phase exhibited unidirectional rotation under a heat flux along the symmetry axis. By introducing colloidal particle adhesive to the Ch droplet surface, we traced the translational motion of the colloids and found that the colloids rotated unidirectionally around the center of each Ch droplet. The director configuration of the droplets was not distorted either spatially or temporally, while the colloids rotated constantly. The results suggest that the Ch droplets under the heat flux should rotate as a rigid body. Using this heat-driven rotation of the Ch droplets, we designed new geometries of various composites of Ch droplets and colloids and succeeded in driving intriguing complex dynamics.

    DOI

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    4
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  • Direct Observation of Unidirectional Rotation of Cholesteric Droplets Subjected to a Temperature Gradient

    Nishiyama Katsu, Tabe Yuka

    AAPPS Bulletin   29 ( 5 ) 40 - 41  2019.10  [Refereed]

  • A thermomechanical coupling in cholesteric liquid crystals: Unidirectional rotation of double-twist cylinders driven by heat flux

    Bono Shinji, Maruyama Yuji, Nishiyama Katsu, Tabe Yuka

    EUROPEAN PHYSICAL JOURNAL E   42 ( 8 )  2019.08  [Refereed]

    DOI

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    9
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  • Direct Observation of Rigid-Body Rotation of Cholesteric Droplets Subjected to a Temperature Gradient

    Nishiyama Katsu, Bono Shinji, Maruyama Yuji, Tabe Yuka

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   88 ( 6 )  2019.06  [Refereed]

    DOI

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    11
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  • Unusual Molecular Diffusion in an Induced SmA Phase Composed of Charge-Transferred Liquid Crystalline Mixtures

    Takei Shoyo, Matsui Eiji, Tabe Yuka

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   88 ( 4 )  2019.04  [Refereed]

    DOI

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    2
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    (Scopus)
  • Photo-Controllable Rotation of Cholesteric Double-Twist Cylinders

    Bono Shinji, Maruyama Yuji, Nishiyama Katsu, Tabe Yuka

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   683 ( 1 ) 39 - 45  2019.04  [Refereed]

    DOI

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    7
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  • Formation and dynamics of the aggregates of cholesteric double-twist cylinders

    Bono Shinji, Maruyama Yuji, Tabe Yuka

    SOFT MATTER   14 ( 48 ) 9798 - 9805  2018.12  [Refereed]

    DOI

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    13
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  • Formation of Concentric Silica Nanogrooves Guided by the Curved Surface of Silica Particles

    Shintaro Hara, Keiya Hirota, Yuka Tabe, Hiroaki Wada, Atsushi Shimojima, Kazuyuki Kuroda

    Langmuir   34 ( 4 ) 1733 - 1741  2018.01  [Refereed]

     View Summary

    The flexible control of nanopatterns by a bottom-up process at the nanometer scale is essential for nanofabrication with a finer pitch. We have previously reported that for the fabrication of linear nanopatterns with sub-5 nm periodicity on Si substrates the outermost surfaces of assembled micelles facing the substrates can be replicated with soluble silicate species generated from the Si substrates under basic conditions. In this study, concentrically arranged nanogrooves with a sub-5 nm periodicity were prepared on Si substrates by replicating the outermost surfaces of bent micelles guided by silica particles. The Si substrates, where silica particles and surfactants films were deposited, were exposed to an NH3-water vapor mixture. During the vapor treatment, cylindrical micelles became arranged in concentric patterns centered on the silica particles, and their outermost surfaces facing the substrates were replicated by soluble silicate species on the Si substrates. The thinness of the surfactant film on the substrate is crucial for the formation of concentric silica nanogrooves because the out-of-plane orientations of the micelles are suppressed at the interface. Surprisingly, the domains of the concentric silica nanogrooves spread to much larger areas than the maximum cross-sectional areas of the particles, and the size of the domains increased linearly with the radii of the particles. The extension of concentric nanogrooves is discussed on the basis of the orientational elastic energies of the micelles around one silica particle. This study of the formation of bent nanogrooves guided by the outlines of readily deposited nanoscale objects provides a new nanostructure-guiding process.

    DOI

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    3
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  • Unidirectional rotation of cholesteric droplets driven by UV-light irradiation

    Shinji Bono, Sayumi Sato, Yuka Tabe

    SOFT MATTER   13 ( 37 ) 6569 - 6575  2017.10  [Refereed]

     View Summary

    We investigated the novel photo-induced dynamics of azobenzene-doped cholesteric (Ch) droplets coexisting with the isotropic (Iso) phase. When the hemispherical Ch droplets initially stuck to glass substrates were irradiated by UV-light, they were parted from the substrates due to the surface disordering caused by the photo-isomerization of azobenzene. Then, the spherical droplets floating in the Iso phase exhibited an unexpected motion - a continuous and unidirectional rotation along the light propagation direction. The rotational direction was reversed by the inversion of either the sample's chirality or the UV irradiation direction, and the rotational velocity increased with both the UV-light intensity and the concentration of the doped azobenzene, the dependences of which were described by linear and relaxation functions, respectively. We proposed a possible scenario based on Leslie's theory combining mass fluxes and torques, which well explained the photo-driven rotation of the Ch droplets.

    DOI

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    23
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  • Unidirectional Heat Transport Driven by Rotating Cholesteric Droplets

    Sayumi Sato, Shinji Bono, Yuka Tabe

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   86 ( 2 )  2017.02  [Refereed]

     View Summary

    When a cholesteric liquid crystal (LC) is submitted to a thermal gradient, it exhibits continuous director rotation. The phenomenon is called the Lehmann effect and is understood as a thermomechanical coupling in chiral LCs without mirror symmetry. Since the Lehmann effect is considered to possess time-reversal symmetry, one can expect the inverse process, i.e., rotating chiral LCs to pump heat along the rotational axis. We report the first observation of heat transport driven by rotating cholesteric droplets. This result suggests a new function of the cholesterics as a micro heat pump.

    DOI

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    5
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  • キラリティを有した液晶微小球の内部構造とその熱駆動回転

    吉岡潤, 伊藤文哉, 多辺由佳

    固体物理   52 ( 7 )  2017  [Refereed]

  • Heat-Driven Rotation in Cholesteric Droplets with a Double Twisted Structure

    Fumiya Ito, Jun Yoshioka, Yuka Tabe

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   85 ( 11 )  2016.11  [Refereed]

     View Summary

    In an isotropic-cholesteric coexistence system, a single-helix structure is formed in the cholesteric droplets, and when a temperature gradient is applied, unidirectional rotations are induced in these droplets. However, in a previous work, we showed that a double twisted structure was also formed in the droplets by changing droplet size or chirality. In this paper, we find that unidirectional rotations are also induced by applying a temperature gradient to droplets with a double twisted structure. Here, however, the rotational behavior is strongly dependent on the relationship between the direction of the helical axis and the temperature gradient. Unidirectional rotation is induced when one of the helical axes is parallel to the gradient, whereas no rotation is found when all of the axes are perpendicular to the temperature gradient. These results suggest that the macroscopic helix plays a significant role in the heat-driven rotational dynamics of cholesteric droplets.

    DOI

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    19
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  • Stability of a double twisted structure in spherical cholesteric droplets

    Jun Yoshioka, Fumiya Ito, Yuka Tabe

    SOFT MATTER   12 ( 8 ) 2400 - 2407  2016  [Refereed]

     View Summary

    We found for the first time the stabilization of a double twisted structure in cholesteric liquid crystals confined to small spherical droplets under weak anchoring conditions. The direct observation of the droplets using a polarized microscope revealed the physical properties of the structure. The experimental results showed that the stability of the double twisted structure is determined by the relationship between the helical pitch length and the droplet size. We theoretically analyzed the structural stability by the calculation of the Frank elastic free energy including the surface elastic term, and succeeded in explaining the experimental results. In this paper, we concluded that the stability of the double twisted structure is determined by the competition between the surface and the bulk elasticity.

    DOI

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    25
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  • Induced smectic phases of stoichiometric liquid crystal mixtures

    Shin-ya Sugisawa, Yuka Tabe

    SOFT MATTER   12 ( 12 ) 3103 - 3109  2016  [Refereed]

     View Summary

    We revealed the detailed structures of induced smectic liquid crystal (LC) phases composed of a binary mixture of charge-transfer (CT) LC substances. Although neither of the constituents had highly ordered smectic phases, the mixture exhibited smectic-E (SmE) or smectic-B (SmB) phases when mixed at ratios of 1:1 and 2:3, respectively. The results of polarized optical microscopy, differential scanning calorimetry, X-ray diffraction, and infrared spectroscopy indicated that the induced smectic phases were stabilized by an exquisite balance between the CT interactions, dipolar interactions, and excluded volume effects. We proposed a possible model for the molecular arrangements in the SmE and SmB phases, which consistently explained the experimental results including the stoichiometric ratios.

    DOI

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    19
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  • 19pBF-12 Mechanical rotation and convective structure in isotropic-cholesteric coexistence system under temperature gradient

    Yoshioka Jun, Tabe Yuka

    Meeting Abstracts of the Physical Society of Japan   71   3173 - 3173  2016

    DOI CiNii

  • PB59 Cross correlation between director rotation and gas permeation through SmC* monolayers investigated by MD simulation

    YAMAGUCHI Kazumasa, TABE Yuka

    Proceedings of Japanese Liquid Crystal Society Annual meeting   2015   _PB59 - 1_-_PB59-2  2015

     View Summary

    By means of MD simulation, we investigated the cross correlation between c-director rotation and gas permeation through SmC* monolayers with applying a rotational electric field. Our simulation results agree with Onsager relation, which predicts that both the c-director rotation and the gas permeation should linearly depend on the rotational E-field and pressure gradient of the gas.

    DOI CiNii

  • PB56 Extraordinary gas permeation of free-standing films composed of binary LC mixtures

    KURAMITSU Ryo, SUGISAWA Shin-ya, TABE Yuka

    Proceedings of Japanese Liquid Crystal Society Annual meeting   2015   _PB56 - 1_-_PB56-2  2015

     View Summary

    Binary mixtures composed of polar and non-polar LC molecules often form highly-ordered smectic phases. We recently found that when several percent of dialkyl-terminated azobenzene is added to 8CB, the mixture considerably loses the fluidity without showing any phase transitions. To understand the origin of this phenomenon, we tried to examine the molecular diffusional in the mixture by means of gas permeation experiment.

    DOI CiNii

  • 3A03 Attempt to prove the reverse process of Lehmann effect in chiral free-standing films

    HANEHARA Sho, HARADA Hirofumi, TABE Yuka

    Proceedings of Japanese Liquid Crystal Society Annual meeting   2015   _3A03 - 1_-_3A03-2  2015

     View Summary

    Free-standing films composed of chiral liquid crystals are known to exhibit the unidirectional director rotation under transmembrane mass flow. The dynamics is well described by Leslie's phenomenological equation, which predicts the inverse process of mass transports driven by the director rotation. In this report, we investigated this inverse effect. Applying a rotating E-field to the film that should drive the unidirectional rotation of the c-director, we simultaneously measured the transported gas through the film.

    DOI CiNii

  • 3A06 Stability of double twisted structure in cholesteric droplets

    Yoshioka Jun, Ito Fumiya, Tabe Yuka

    Proceedings of Japanese Liquid Crystal Society Annual meeting   2015   _3A06 - 1_-_3A06-2  2015

     View Summary

    Recently, in the system where the droplets formed by the cholesteric liquid crystal are dispersed in the isotropic medium, we found double twisted structure is stabilized. As the chirality of the system or the size of the droplets increases, the structure transits from the double twisted into the single helix structure. Moreover, calculating the elastic free energy in the system, we succeeded in explaining the structural transition described above theoretically.

    DOI CiNii

  • 3A08 Coupling between rotational motion of cholesteric LC droplets and transport current

    Sato Sayumi, Yoshioka Jun, Tabe Yuka

    Proceedings of Japanese Liquid Crystal Society Annual meeting   2015   _3A08 - 1_-_3A08-2  2015

     View Summary

    Cholesteric LC droplets dispersed in isotropic phase are known to exhibit a unidirectional barycentric rotation under a temperature gradient. Theoretically, Onsager relation predicts such interesting inverse process that the rotation of cholesteric droplets should transport a heat along the rotational axis. We tried to cause the heat current by mechanically rotating the cholesteric droplets in the isotropic phase. Although a convincing result has not been obtained, we noticed some difference between the cholesteric droplets and nematic ones.

    DOI CiNii

  • 3A07 Heat-driven rotation and convection in isotropic droplets in cholesteric liquid crystals

    Yoshioka Jun, Tabe Yuka

    Proceedings of Japanese Liquid Crystal Society Annual meeting   2015   _3A07 - 1_-_3A07-2  2015

     View Summary

    Making isotropic droplets in the cholesteric (Ch) liquid crystal, we found spiral textures appear on the interface between the Ch liquid crystal and the droplets. Moreover, applying temperature gradient to this system, we found the texture rotates. To clarify the origin of this heat-driven rotation, we analyzed the flow field in the system. As a result, it was found convection is induced in the droplet when temperature gradient is applied; thus, we concluded this convection is the physical origin of the heat-driven rotation.

    DOI CiNii

  • 1A05 Structural formation of induced smectic phases : its analogy with metal alloy

    SUGISAWA Shin-ya, TABE Yuka

    Proceedings of Japanese Liquid Crystal Society Annual meeting   2015   _1A05 - 1_-_1A05-2  2015

     View Summary

    We performed structural analysis of induced smectic phases, which are composed of polar and non-polar liquid-crystalline molecules. Unlike the conventional understanding that induced smectic phases originate from the formation of charge-transfer (CT) complexes, we revealed that when the CT interaction strength is not so strong, the binary system spontaneously selects the specific integer composition ratio other than 1:1. Our results suggest that the structural formation of induced smectic phases exhibits remarkable similarities to that of metal alloys; that is, the structural stabilization is realized by not only the CT interaction, but also the contributions of molecular-packing effects.

    DOI CiNii

  • 1A06 Spontaneous chiral symmetry breaking in smectic-E liquid crystalline films

    SUGISAWA Shin-ya, NAGATA Tatsuya, TABE Yuka, OSHIMA Chuhei

    Proceedings of Japanese Liquid Crystal Society Annual meeting   2015   _1A06 - 1_-_1A06-2  2015

     View Summary

    We observed diffraction patterns of smectic E (SmE) phase by using our home-made electron microscope. The advantage of our system is the low-electron beam; this significantly reduces the radiation damage to specimen, and enabled us to observe SmE films without any cryogenic technique. We found in particular that diffraction patterns of SmE phase as an induced smectic phase exhibit unidirectional rotations under electron beams. Since such rotations were not observed in the case of usual SmE phase, we revealed that induced SmE phase possesses well-regulated molecular aliments in the in-plane herringbone lattice, which realizes the spontaneous chiral symmetry breaking.

    DOI CiNii

  • 19aCU-07 Stability of double twisted structure confined to spherical region

    Yoshioka Jun, Ito Fumiya, Tabe Yuka

    Meeting Abstracts of the Physical Society of Japan   70   3026 - 3026  2015

    DOI CiNii

  • 22pPSA-26 誘起スメクチック液晶相で作成したバブルの示す異常破壊ダイナミクス

    杉澤 進也, 小林 健介, 多辺 由佳

    日本物理学会講演概要集   70   3328 - 3328  2015

    DOI CiNii

  • 24pAA-6 Heat-current-driven director/barycentric rotation induced by helical structure in cholesteric droplets

    Yoshioka Jun, Ito Fumiya, Tabe Yuka

    Meeting Abstracts of the Physical Society of Japan   70   3432 - 3432  2015

    DOI CiNii

  • Director/barycentric rotation in cholesteric droplets under temperature gradient

    Jun Yoshioka, Fumiya Ito, Yuto Suzuki, Hiroaki Takahashi, Hideaki Takizawa, Yuka Tabe

    SOFT MATTER   10 ( 32 ) 5869 - 5877  2014  [Refereed]

     View Summary

    When a chiral liquid crystal is given a transport current, a unidirectional molecular motion is known to take place, which is called the Lehmann effect. In this paper, we study the mysterious heat-current-driven Lehmann effect using two types of hemispherical cholesteric droplets using polarizing, reflecting, confocal and fluorescent microscopies. Both the droplets, coexisting with the isotropic phase and contacting on a glass substrate, are characterized by the concavo-convex modulated surface and the inside orientational helix. Further, the only difference between them is the helical axis direction; i.e., one is perpendicular and the other is parallel to the substrate. Under the temperature gradient perpendicular to the substrate, the droplet whose helical axis is parallel to the heat current exhibited pure director rotation, while that with the axis perpendicular to the current rotated independently as a rigid body. In the two droplets, the rotational conversion efficiency from the temperature gradient into the angular velocity showed very different dependences on the chirality strength and on the droplets' size, suggesting that the rotations of the two droplets may be driven by independent torques with different origins. This is the first observation that the cholesteric droplets under the temperature gradient exhibit the two rotational modes, the pure director rotation and the molecular barycentric motion, which can be switched to each other by changing the heat current direction parallel and perpendicular to the helical axis.

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  • Periodic Deformation of LC-Isotropic Interface Induced by Interior Orientational Distortion

    Sato Sayumi, Ito Fumiya, Suzuki Yuto, Takizawa Hideaki, Yoshioka Jun, Tabe Yuka

    Proceedings of Japanese Liquid Crystal Society Annual meeting   2014   PB44  2014

     View Summary

    <p>We study the nematic-isotropic interface under an electric field by confocal microscopy. In the N-I coexisting temperature region, the interface is initially flat and is deformed into a periodically modulated shape by a weak AC field. The amplitude and the wavenumber of the modulation monotonically increased with the electric field.</p>

    DOI CiNii

  • Gas permeability through free-standing LC films: dependence on director field

    Hanehara Sho, Harada Hirohumi, Tabe Yuka

    Proceedings of Japanese Liquid Crystal Society Annual meeting   2014   PB47  2014

     View Summary

    <p>The gas permeability through free-standing LC films is known to depend on the molecular structures and the LC phases. In this report, we examine the dependence of the gas permeability on the dynamical director field, which was inspired by Lehmann effect driven by transmembrane gas transport. We study how the gas permeability is affected by the director field and motion.</p>

    DOI CiNii

  • Unidirectional rotation of cholesteric droplets with rugby -like texture driven by thermal flow

    Ito Fumiya, Suzuki Yuto, Takizawa Hideaki, Sato Sayumi, Yoshioka Jun, Tabe Yuka

    Proceedings of Japanese Liquid Crystal Society Annual meeting   2014   3A01  2014

     View Summary

    <p>In the isotropic-cholesteric (Ch) coexistence phase of a cyano-biphenyl LC with a chiral dopant, we found four types of Ch droplets associated with the crossed, striped, rugb y and concentric-circle (CC) textures under polarizing optical microscopy (POM). When a temperature gradient was applied to the sandwiched cell perpendicular to the glass substrates, the droplets except for the one with the crossed texture showed the cons tant unidirectional rotation. We analyzed the rotational behavior in comparison with the helical structure inside the droplets.</p>

    DOI CiNii

  • Interaction between the cholesteric droplets under an electrix field

    Suzuki Yuto, Takizawa Hideaki, Ito Fumiya, Sato Sayumi, Yoshioka Jun, Tabe Yuka

    Proceedings of Japanese Liquid Crystal Society Annual meeting   2014   PA51  2014

     View Summary

    <p>In the coexisitence region of cholesteric and isotropic phases, we observe the hemispherical cholesteric droplets accompanied by the helix inside confined on a glass substrate. Under the electric field parallel to the substrate, the droplets rotate to orient the helical axis perpendicular to the field and at the same time, interact each other. The force between the droplets shows the clear dependence on both the relative direction and the distance between the droplets.</p>

    DOI CiNii

  • Director/Barycentric rotation of cholesteric droplets under heat flow

    Yoshioka Jun, Ito Fumiya, Suzuki Yuto, Tabe Yuka

    Proceedings of Japanese Liquid Crystal Society Annual meeting   2014   3A02  2014

     View Summary

    <p>Recently, in the system where the droplets formed by the cholesteric liquid crystal are dispersed in the isotropic medium, it has been reported the textures on the droplets rotate when temperature gradi ent is applied to the system. In this study, to clarify the mechanism of the rotational motion, we analyzed the structure of the droplets and the dynamics of the motion using polarized microscopy and flow-field measurements with photo-bleaching method.</p>

    DOI CiNii

  • Extra-ordinary membrane disruption dynamics of smectic bubbles

    Sugisawa Shin-Ya, Kobayashi Kensuke, Tabe Yuka

    Proceedings of Japanese Liquid Crystal Society Annual meeting   2014   3A03  2014

     View Summary

    <p>We found an extra-ordinary disruption dynamics of smectic bubbles composed of the binary system of polar and non-polar LC molecules. Unlike the typical liquid-like bursting dynamics seen in usual SmA phase, we observed during the disruption polymer-like, network-formations and dramatically increase in the timescale. Although it has been known that such mixtures exhibit higher ordered induced smectic phase, such dynamics were found even in the case of SmA phase. In this report, we discuss the dependence of the characteristics of dynamical properties on temperature, concentration, and film thickness, and propose the physical mechanism in the light of the 'dynamic asymmetry'.</p>

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  • Theoretical analysis of the spontaneous deformation of LC-isotropic interface

    Takizawa Hideaki, Yoshioka Jun, Tabe Yuka

    Proceedings of Japanese Liquid Crystal Society Annual meeting   2014   3A14  2014

     View Summary

    <p>When an external field such as electric and magnetic fields is applied to a liquid-liquid interface, we often encounter the deformation of the interface. In the case that one of the liquids is liquid crystal, the deformation should be associated with the director modulation. Here, we study the modulated structure of the surface of a liquid crystal sample without any external field. Under the strong anchoring conditions, the competition between the interfacial tension and the interior orientational elasticity should determine the periodic modulation of the interface.</p>

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  • Molecular Dynamics Simulation Study of Two-Dimensional Diffusion Behavior in Smectic Liquid Crystalline Monolayers

    Go Watanabe, Jun-ichi Saito, Yusuke Fujita, Yuka Tabe

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   82 ( 8 )  2013.08  [Refereed]

     View Summary

    We have carried out molecular dynamics (MD) simulations for monolayers of smectic A and C liquid crystal (LC) phases in order to investigate the in-plane molecular diffusion from the microscopic point of view. In contrast to similar complex two-dimensional systems (e.g., biomembranes) whose molecular diffusion is anomalous, in-plane mean square displacements (MSDs) for both phases increase linearly with passing time similar to typical fluids on the nanosecond time scale. By following the relation between the diffusion and the viscosity in the fluids, we estimated the viscosity coefficients for both LC monolayers, and the obtained values indicate that the smectic A monolayer has a higher viscosity than the smectic C one. Moreover, we investigate the in-plane self-diffusion anisotropy D-parallel to/D-perpendicular to for smectic C and found that the diffusion parallel to the molecular tilt is 1.5 times larger than that in the perpendicular direction. This anisotropic diffusion property in the smectic C monolayer has not been clearly confirmed thus far.

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  • 3a13 Heat-driven rotational motion in cholesteric droplets with stripe textures

    Yoshioka Jun, Ito Fumiya, Suzuki Yuto, Takahashi Hiroaki, Tabe Yuka

    Proceedings of Japanese Liquid Crystal Society Annual meeting   2013   _3a13 - 1_-_3a13-2  2013

     View Summary

    The cholesteric droplets with stripe textures dispersed in the coexisting isotropic medium are known to rotate their textures under a temperature gradient. In spite of the clear observation, it is not known whether the rotation of the stripes should correspond to the director rotation or the barycentric rotation of the droplets. To clarify the rotational mechanism, we investigated the detailed structure of the cholesteric streaky droplets by using polarized and confocal fluorescence microscopy and analyzed the relation between the structure and the rotational speed of the droplets.

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  • 3a05 Molecular Dynamics simulation of gaseous diffusion in smectic LC membranes

    Tsukahara Naoki, Ohashi Yoriki, Fujita Yusuke, Tabe Yuka

    Proceedings of Japanese Liquid Crystal Society Annual meeting   2013   _3a05 - 1_-_3a05-2  2013

     View Summary

    The diffusion of small gas molecules in smectic LC films is examined by Molecular Dynamic (MD) Simulation. When the solute molecules are smaller than the solvent constituents, the diffusion is known to deviate from Stokes-Einstein's law, which cannot be described by any general equations. We carried the MD simulation of the gaseous motion in smectic membranes and comparedto some experimental results.

    DOI CiNii

  • 3a15 Non-linear oscillation of smectic bubbles under DC field

    Hanehara Sho, Sugisawa Shin-ya, Harada Yuki, Tabe Yuka

    Proceedings of Japanese Liquid Crystal Society Annual meeting   2013   _3a15 - 1_-_3a15-2  2013

     View Summary

    Hemispherical smectic bubbles exhibit nonlinear deformation under a DC field. When a bubble on a flat substrate is given the higher DC field than a threshold, it expands to touch the upper electrode and return back, the process of which is repeated with a constant period. By measuring the electric current through the bubble, we confirmed that the bubbles' nonlinear oscillation should be ascribed to the accumulation and release of the charges on the bubble surface. The oscillation period can be controlled in a wide range by changing the applied voltage and the bubbles' resistance.

    DOI CiNii

  • 3a14 Anomalous ordering by intermixing of two monocomponent SmA phases

    Sugisawa Shin-ya, Kobayashi Kensuke, Tabe Yuka

    Proceedings of Japanese Liquid Crystal Society Annual meeting   2013   _3a14 - 1_-_3a14-2  2013

     View Summary

    We found that the simply intermixing of two monocomponent LC materials induced the unusual phase ordering. In the binary mixture, the transition temperature between the isotropic and LC phases increased significantly, and the higher-ordered phases of SmB appeared at the lower temperature, which could never be seen in either of the original materials. The result of POM observation, DSC and X-ray diffraction measurements suggests that the "anomalous ordering" could be ascribed to a certain kind of micro-phase segregation.

    DOI CiNii

  • PB09 Rotation of cholesteric droplets under temperature gradient : Dependence of rotation speed on chirality

    Suzuki Yuto, Yoshioka Jun, Tabe Yuka

    Proceedings of Japanese Liquid Crystal Society Annual meeting   2013   _PB09 - 1_-_PB09-2  2013

     View Summary

    We studied the unidirectional rotation of cholesteric droplets driven by thermal flow. The polarizing microscopy observation showed that the droplets under temperature gradient took two different types of dynamics: When the cholesteric helical axis is parallel to the thermal flow, the transmitted light through the droplets temporally changes its intensity with a certain period, the speed of which increases with the chirality. In contrast, the droplets with the helix axis perpendicular to the heat current showed much slower dynamics, the speed of which decreases with the chirality strength. We suggest that the two dynamics of the cholesteric droplets may correspond to the unidirectional rotation of the director and that of the droplets themselves.

    DOI CiNii

  • Pre-organized liquid crystals: biaxial nature of laterally-connected dimer

    Isa Nishiyama, Yuka Tabe, Jun Yamamoto, Yoichi Takanishi, Yoko Ishii, Hiroshi Yokoyama

    EMERGING LIQUID CRYSTAL TECHNOLOGIES VII   8279  2012  [Refereed]

     View Summary

    Biaxial nematic liquid crystals have attracted much attention from both fundamental and application points of view, because the fast response based on the rotation of the minor director is expected. So far, different molecular designs have been proposed for the emergence of the biaxial nematic phase. Among that, we have been interested in applying "preorganization" concept on generating the biaxiality. Dimeric liquid crystal compounds have been prepared in line with this concept in which two mesogenic parts are linked by the biphenyl connecting group. The pre-organized dimmer shows an anomalous textural change, for vertically-aligned and free-standing film samples, at the smectic C (SmC)-nematic (N) phase transition, in which the Schlieren texture of the SmC changes into the other Schlieren texture of the N phase. There are two possible explanations for this textural change, i.e., the occurrence of the director change at the SmC-N phase transition or the emergence of biaxiality in the N phase. The electric-field-induced birefringence has also been measured in detail for investigating the biaxial nature of the sample.

    DOI

    Scopus

  • Lehmann Force Acting on a Micro-Particle in Smectic C* Free-Standing Films Subjected to Methanol Vapor Transport

    Kazuyoshi Seki, Ken Ueda, Kazuhisa Uda, Kazumasa Tsunekawa, Yuka Tabe

    JAPANESE JOURNAL OF APPLIED PHYSICS   50 ( 12 )  2011.12  [Refereed]

     View Summary

    Gas permeation through smectic C* free-standing films causes a unidirectional director rotation, occasionally accompanied by a unidirectional vortex-like hydrodynamic flow. In this study, by placing ZrO2 micro-particles on the film subjected to methanol vapor transport, we observed the particle motions and measured a drag force acting on them. The particles underwent a unidirectional quasi-circular motion with the velocity linear to the methanol transfer rate with the magnitude of the drag force being on the order of several pN that increased approximately linearly with the velocity of the flow. A simple analysis shows that the conversion efficiency from the transmembrane methanol current to the drag force on the particles is similar to 1.4 x 10(-10) N.s.m(2)/mol in our system. The present hydrodynamic experiment is complementally to the previous observations of linear director rotation in the Lehmann effect, which well supports Leslie's phenomenological theory. (C) 2011 The Japan Society of Applied Physics

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    2
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  • Non-equilibrium dynamics of 2D liquid crystals driven by transmembrane gas flow

    Kazuyoshi Seki, Ken Ueda, Yu-ichi Okumura, Yuka Tabe

    JOURNAL OF PHYSICS-CONDENSED MATTER   23 ( 28 )  2011.07  [Refereed]

     View Summary

    Free-standing films composed of several layers of chiral smectic liquid crystals (SmC*) exhibited unidirectional director precession under various vapor transfers across the films. When the transferred vapors were general organic solvents, the precession speed linearly depended on the momentum of the transmembrane vapors, where the proportional constant was independent of the kind of vapor. In contrast, the same SmC* films under water transfer exhibited precession in the opposite direction. As a possible reason for the rotational inversion, we suggest the competition of two origins for the torques, one of which is microscopic and the other macroscopic. Next, we tried to move an external object by making use of the liquid crystal (LC) motion. When a solid or a liquid particle was set on a film under vapor transfer, the particle was rotated in the same direction as the LC molecules. Using home-made laser tweezers, we measured the force transmitted from the film to the particle, which we found to be several pN.

    DOI

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    14
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  • Orientational correlations in two-dimensional liquid crystals studied by molecular dynamics simulation

    Go Watanabe, Jun-Ichi Saito, Nobuyuki Kato, Yuka Tabe

    JOURNAL OF CHEMICAL PHYSICS   134 ( 5 )  2011.02  [Refereed]

     View Summary

    Orientational correlations in Langmuir monolayers of nematic and smectic-C liquid crystal (LC) phases are investigated by molecular dynamics simulation. In both phases, the orientational correlation functions decay algebraically yet with the different exponents of 1.9 and 0.2 for the nematic and the smectic-C monolayers, respectively. The power law decay, i.e., the absence of long-range orientational order, means the both monolayers should be the ideal 2D system with a continuous symmetry, whereas the large difference in the exponents of power law gives rise to the crucial difference in their optical properties; the nematic monolayer is optically isotropic while the smectic-C monolayer exhibits an anisotropy on the length scale of visible light. Since the exponent is inversely proportional to the molecular exchange energy, the averaged molecular interaction in the nematic monolayer should be an order of magnitude smaller than that in the smectic-C monolayer, which is ascribed to the low molecular density and the weak molecular dipole due to the water molecule. The relation between the molecular interaction and the orientational correlation calculated for the 2D LC system offers much information not only about the 2D LCs but also on the bulk system. (C) 2011 American Institute of Physics. [doi:10.1063/1.3536519]

    DOI

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    11
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  • Anomalous Deformation of Smectic Bubbles under DC Electric Field

    Yoko Ishii, Shin-Ya Sugisawa, Yuka Tabe

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   549   166 - 173  2011  [Refereed]

     View Summary

    Hemispherical bubbles composed of smectic liquid crystals show an unusual deformation under DC electric field. When the lower voltage than a threshold is applied to the bubble on a substrate, it is elongated in the direction of the electric field and forms a semi-elliptical shape in the equilibrium. With the higher voltage than the threshold, the bubble becomes unstable and sometimes exhibits a periodic oscillation with repeating the elongation and shrinkage. Based on a simple equation of force balance, we analyzed both the static and dynamic deformations under DC field and successfully reproduced the observed behaviour. By the detailed analysis, we also determined the surface tension and the electric conductivity of the smectic bubbles.

    DOI

    Scopus

    3
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  • Pre-Organization Effects on Chirality, Polarity and Biaxiality in Liquid Crystals: Novel Laterally Connected Mesogens showing Anomalous Properties

    Isa Nishiyama, Yuka Tabe, Jun Yamamoto, Hiroshi Yokoyama

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   549   174 - 183  2011  [Refereed]

     View Summary

    Pre-organization effects are investigated for the laterally-connected liquid crystals possessing a biphenyl connecting group. The homeotropic texture of the N phase of a free-standing film sample was found to change into the other "Schlieren" texture on cooling even in the N phase, which then changes into the "Schlieren" texture of the SmC phase on further cooling. The possibility of the emergence of biaxiality in the N phase is discussed.

    DOI

    Scopus

    3
    Citation
    (Scopus)
  • Molecular Dynamics Simulation of Condensed-Phase Chiral Molecular Propellers

    M. Yoneya, Y. Tabe, H. Yokoyama

    JOURNAL OF PHYSICAL CHEMISTRY B   114 ( 25 ) 8320 - 8326  2010.07  [Refereed]

     View Summary

    Molecular dynamics simulations were performed for an axial-chiral liquid crystalline (LC) monolayer under trans-monolayer gas flow. The rotational dynamics of the monolayer chiral LC molecule along its long-molecular axis were analyzed at the molecular level. We found a precise correspondence between the flow-driven molecular rotation direction and molecular chirality as well as between the rotation direction and the trans-monolayer flow direction. The rotational direction exactly corresponded to what was expected in the proposed chiral molecular propeller model (Tabe, Y.; Yokoyama, H. Nat. Mater. 2003, 2, 806). Among the four trans-monolayer gas species we investigated, we found argon to be the most efficient at driving the chiral molecular propeller and helium the least efficient.

    DOI

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    8
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  • Gas permeation of LC films observed by smectic bubble expansion

    Y. Ishii, Y. Tabe

    EUROPEAN PHYSICAL JOURNAL E   30 ( 3 ) 257 - 264  2009.11  [Refereed]

     View Summary

    Gas permeation through liquid crystal (LC) films was examined using hemispherical smectic bubbles. A smectic bubble, when the inside and the outside are filled with different gases, should expand or shrink toward the quasi-equilibrium state, where the influx and efflux caused by osmotic pressure are balanced. Deriving a simple formula that directly converts the quasi-equilibrated bubble radius to the gas permeation, we determined the absolute permeability coefficients of 8 simple gases through the smectic bubble. The permeability was distributed in such a wide range that carbon-dioxide had more than 20 times larger value than nitrogen, the dependence of which on the gas species was mostly dominated by their solubility into the LCs. Dividing the measured permeability by the calculated solubility, we obtained the diffusion constants as well, yet whose magnitude and the dependence on the solute size could not be explained by either conventional continuum theories or microscopic diffusion models. In order to describe the diffusion of small solutes in the liquid solvent composed of large molecules, a new theoretical framework may be necessary.

    DOI

    Scopus

    8
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  • Photochemical transformation of topological defects formed around colloidal droplets dispersed in azobenzene-containing liquid crystals

    Takahiro Yamamoto, Yuka Tabe, Hiroshi Yokoyama

    COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS   334 ( 1-3 ) 155 - 159  2009.02  [Refereed]

     View Summary

    We investigated photochemical transformation of asymmetric topological defects formed around water droplets dispersed in the azobenzene-containing liquid crystals. It was found that initial structures and the photo-induced phenomena of the defects were clearly affected by chemical structures of the azobenzene compounds. In quite strong homeotropic anchoring obtained by using the azobenzene compound with a long alky chain, the hedgehog was formed around the droplets at the initial state. When the anchoring strength was decreased by changing the carbon number of the alkyl chain, a novel asymmetric defect which will be an intermediate structure between the hedgehog and the Saturn ring was observed. The ionic groups had an influence on the photochemical transformation of the defects. The azobenzene compound with a smaller ionic group induced only a change in the anchoring strength, and a disappearance of the hedgehog was observed on the irradiation with ultra-violet light. In the case of the azobenzene compound with a larger ionic group, photochemical switching of the anchoring and the transformation into the boojums was achieved. The photo-induced phenomena could be qualitative explained by an effectiveness of the cis-trans photoisomerization depending on molecular areas of the azobenzene compounds determined by the ionic groups. (C) 2008 Elsevier B.V. All rights reserved.

    DOI

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    14
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  • Manipulation of Defect Structures and Colloidal Chains in Liquid Crystals by Means of Photochemical Reactions of Azobenzene Compounds

    Takahiro Yamamoto, Yuka Tabe, Hiroshi Yokoyama

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   498   1 - 10  2009  [Refereed]

     View Summary

    Photonic control of defect structures and colloidal chains has been performed in azobenzene-containing liquid crystals dispersed with glycerol or water droplets. When we dispersed the colloidal droplets into the host liquid crystals, we could observe, at an initial state, Saturn ring and hedgehog around the glycerol and water droplets, respectively, indicating that normal alignment of liquid crystal molecules was induced on the droplets by the adsorption of the azobenzene molecules onto the droplets. In the case of the glycerol droplets, we achieved photochemical manipulation of the defect structures between Saturn ring and boojums on irradiation with ultra-violet and visible light. For the water droplets, an inter-droplet distance of the self-organized colloidal chain could be controlled by changes of the defect size on the photoirradiation. Photoinduced structural changes in the topological defects can be explained by the modulation of surface anchoring of the droplets by means of the cis-trans photoisomerization of the adsorbed azobenzene molecules.

    DOI

    Scopus

    2
    Citation
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  • Molecular dynamics simulation study of gas transport through chiral liquid crystalline monolayer

    M. Yoneya, Y. Tabe, H. Yokoyama

    FERROELECTRICS   365   297 - +  2008  [Refereed]

     View Summary

    Molecular dynamics simulations were done for a chiral liquid crystalline (LC) monolayer with and without transmonolayer H-2 gas flow. The rotational dynamics of the monolayer LC molecule (MHPOBC) along its long-molecular axis was analyzed by tracing the orientations of the C=O bond close to the chiral part. We found that the reorientational motion along the molecular long-axis within the simulated time scale (10ns) was mostly not rotation but libration. We also found that the transmonolayer H-2 gas flow renders no apparent effects on the rotational motions of the MHPOBC molecules. Dependency of the MHPOBC rotational directions under the gas flow on the molecular chirality was not seen either. In contrast, marked chirality dependency was found in the asymmetry of the C=O orientational distributions that are oppositely biased each other between (S)- and (R)-MHPOBC. Resultant net polarization directions from these biased C=O distributions correspond to the experimentally reported spontaneous polarization (P-s) directions. It suggests that in our simulations, P-s and its direction were determineded as the "biased distribution" within much shorter time scale than that for the "hindered rotation".

    DOI

    Scopus

    7
    Citation
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  • Tilted and non-tilted liquid crystalline langmuir monolayers: Analogy to bulk smectic phases

    Go Watanabe, Yuka Tabe

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   76 ( 9 )  2007.09  [Refereed]

     View Summary

    Hydrophobic compounds of smectic liquid crystals are spontaneously spread on a liquid surface to form softly-condensed monomolecular films. The constituent molecules are coherently tilted from the surface normal when they form smectic-C phase in the bulk state, while the molecules are aligned perpendicular to the surface when they form smectic-A or -B phase in the bulk. The result proves that the tilting property in the smectic liquid crystals should be determined only by the intralayer molecular interaction. The molecular dynamics simulations can reproduce the experimental result satisfactorily and also suggest that the molecular dipole moment should play an essential role to cause the coherent molecular tilt in smectic liquid crystals.

    DOI

    Scopus

    4
    Citation
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  • Air tube formation at the freezing transition in nematic liquid crystals

    C. Voltz, Y. Maeda, Y. Tabe, H. Yokoyama

    PHYSICAL REVIEW E   75 ( 3 ) 031702  2007.03  [Refereed]

     View Summary

    A phenomenon is presented, which changes the shape of gas bubbles in liquid crystals and also creates long gas tubes. The system consists of air bubbles which are injected into a nematic liquid crystal host. The shape of these air bubbles changes from spherical to ellipsoidal by initiating freezing of the sample. Furthermore, long gas tubes are formed from the air which was formerly dissolved in the liquid crystal. The gas tubes are created by the progression of the crystalline-liquid interface. Their length can reach up to 40 times their diameter. The diameter of the tubes depends on the pressure applied to the system, as well as on the interface velocity.

    DOI

    Scopus

    3
    Citation
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  • Light-induced transformation of defect structures in photochromic liquid-crystal emulsions

    Takahiro Yamamoto, Hiroshi Yokoyama, Yuka Tabe

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   478   967 - 975  2007  [Refereed]

     View Summary

    We investigated photoresponsive behavior of azobenzene-containing liquid crystals dispersed with glycerol or water droplets. At an initial state, Saturn ring and hedgehog defects were formed around the glycerol and water droplets, respectively, indicating that homeotropic anchoring was induced by adsorption of the azobenzene molecules onto the droplets. For the glycerol droplets, we observed structural transformation between Saturn ring and boojums on irradiation with ultra-violet and visible light. For the water droplets, an inter-droplet distance varied by changes of the defect size on the irradiation. These phenomena would result from modulation of anchoring conditions by the photoisomerization of the adsorbed dyes.

    DOI

    Scopus

    3
    Citation
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  • Photo-induced Orientational Waves in Liqid Crystalline Langmuir Monolayers

    TABE Yuka

    Kobunshi   56 ( 7 ) 514 - 514  2007

    DOI CiNii

  • Photochemical manipulation of colloidal structures in liquid-crystal colloids

    T. Yamamoto, Y. Tabe, H. Yokoyama

    LIQUID CRYSTALS AND APPLICATIONS IN OPTICS   6587  2007  [Refereed]

     View Summary

    We investigated photochemical manipulation of physical proper-ties and colloidal structures of liquid-crystal (LC) colloids containing azobenzene compounds. In a LC suspension where polymeric particles were dispersed in a host LC, we achieved photochemical control of light-scattering properties of the suspension. In a nematic phase, when the suspension was sandwiched with two glass plates, the film became opaque. This would be attributable to an appearance of both multidomain structures of LC alignment and mismatches of refractive indices between the materials. The opaque state turned into a transparent one when a nematic-to-isotropic phase transition was induced by the trans-to-cis photoisomerization of the azo-dye. This will result from a disappearance of both the multidomain structures and the refractive-index mismatches in the isotropic phase. The transparent film went back into the initial opaque film when the nematic phase was obtained by the cis-to-trans photoisomerization. In a LC emulsion in which glycerol or water droplets were dispersed in liquid crystals, we examined photochemical change of defect structures and inter-droplet distances by the photochemical manner. At the initial state, Saturn ring and hedgehog defects were formed around the droplets. For the glycerol droplets, we observed structural transformations between Saturn ring and boojums on irradiation with ultra-violet and visible light. For the water droplets, the inter-droplet distances varied by changing defect size on the irradiation. These phenomena would result from modulation of anchoring conditions of the droplets by the photoisomerization of the azo-dyes.

    DOI

    Scopus

    1
    Citation
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  • Director-configurational transitions around microbubbles of hydrostatically regulated size in liquid crystals

    C. Voeltz, Y. Maeda, Y. Tabe, H. Yokoyama

    PHYSICAL REVIEW LETTERS   97 ( 22 ) 227801  2006.12  [Refereed]

     View Summary

    A high-pressure technique is introduced which allows a continuous variation of the inclusion size in liquid crystal colloids. We use a nematic liquid crystal host into which micrometer-sized gas bubbles are injected. By applying hydrostatic pressures, the diameter of these gas bubbles can be continuously decreased via compression and absorption of gas into the host liquid crystal, so that the director configurations around a single bubble can be investigated as a function of the bubble size. The theoretically predicted transition from a hyperbolic hedgehog to a Saturn-ring configuration, on reduction of the particle size below a certain threshold, is confirmed to occur at the radius of a few micrometers.

    DOI

    Scopus

    36
    Citation
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  • Photonic manipulation of topological doped with azober defects in liquid-crystal emulsions zene derivatives

    Takahiro Yamamoto, Yuka Tabe, Hiroshi Yokoyama

    THIN SOLID FILMS   509 ( 1-2 ) 81 - 84  2006.06  [Refereed]

     View Summary

    By modulating liquid-crystal alignment on a colloidal sphere, we successfully manipulated topological defects in glycerol-droplet/liquidcrystal emulsions doped with amphiphilic, azobenzene derivatives. At an initial state, a disclination loop (Saturn ring) could be observed around the droplet, in which the azobenzene molecules should adsorb onto the droplet and liquid crystal molecules align normally to the surface of the droplet. On irradiation with ultra-violet light (lambda = 365 nm), the disclination loop was unfastened and transformed into two point defects called boojums. This should be attributed to the alignment change of the liquid crystal molecules from normal to planar arrangement triggered by trans-to-cis photoisomerization of the adsorbed azo-dyes. On irradiation with visible light causing cis-to-trans photoisomerization (lambda = 43 5 mn), the boojums went back to the Saturn ring reversibly. (c) 2005 Elsevier B.V. All rights reserved.

    DOI

    Scopus

    14
    Citation
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  • Nonequilibrium dynamics of chiral smectic films

    Okuzono Tohru, Tabe Yuka

    Proceedings of Japanese Liquid Crystal Society Annual meeting   2006   221 - 221  2006

     View Summary

    Our recent experiments show that the Lehmann-type rotation occurs in chiral smectic-C films in the presence of mass flux through the films and macroscopic target or spiral patterns are formed.This phenomenon is similar to that observed in Langmuir monolayers with chiral dopants [Tabe and Yokoyama, Nature Mater. 2, 806 (2003)].However, formation processes of the macroscopic patterns in these systems are different.We discuss the difference of the physical nature between these systems and propose a possible model for the dynamics of chiral smectic films.

    DOI CiNii

  • Alignment control of particle chains formed in liquid-crystal colloids by an azo-dye layer

    YAMAMOTO TAKAHIRO, NISHIYAMA ISA, TABE YUKA, YOKOYAMA HIROSHI

    Proceedings of Japanese Liquid Crystal Society Annual meeting   2006   79 - 79  2006

     View Summary

    By means of an azo-dye layer consists of Brilliant Yellow (BY), we successfully achieved an alignment control of chain-like structures formed with colloidal particles dispersed in liquid-crystals. On diagonal irradiation of the layer with unpolarized ultra-violet light, the chain-like structures exhibited an in-plane rotation toward the irradiated light. At the same time, we observed alignment change of bulk liquid crystal in a polarized optical microscope. Therefore, the photoinduced rotation of the colloidal structures will be responsible to the photoinduced alignment change of the liquid crystal molecules on the azo-dye aligning layer.

    DOI CiNii

  • Micro-bubbles in liquid crystals

    Voeltz Camilla, Maeda Yoji, Tabe Yuka, Yokoyama Hiroshi

    Proceedings of Japanese Liquid Crystal Society Annual meeting   2006   118 - 118  2006

     View Summary

    The director orientation around gas bubbles in liquid crystalline emulsions has been investigated. We introduce a new technique which allows a continuous variation of the bubble size. A nematic liquid crystal host is used into which micrometer–sized gas bubbles are injected. By applying pressure to the system, the diameter of these gas bubbles can be continuously varied. A transition from a hyperbolic hedgehog configuration to a saturn ring configuration is found when continuously decreasing the particle size. Furthermore, an electric field has been applied to the system, in order to control the director orientation around the bubbles. In addition to controlling the size of the gas inclusions, their shape can also be controlled, and long air tubes can be created.

    DOI CiNii

  • A phenomenological model of photo-induced traveling waves in liquid-crystalline langmuir monolayers

    Tohru Okuzono, Yuka Tabe, Hiroshi Yokoyama

    Molecular Crystals and Liquid Crystals   435   233 - 242  2005  [Refereed]

     View Summary

    A phenomenological model of photo-induced traveling waves in liquid-crystalline Langmuir monolayers is presented. A linear stability analysis and numerical simulations of this model reveal that there are two oscillatory unstable modes with lower and higher wavenumbers which cause the traveling waves. The unstable mode with the lower wavenumber arises due to an interplay between the spontaneous splay deformation of liquid crystal order and the anisotropic photoexcitation of molecules. The other unstable mode with the higher wavenumber is concerned with the phase separation of the concentration field induced by the spontaneous splay deformation. The numerical simulations also show the coexistence between these two modes for certain parameter values.

    DOI

    Scopus

    1
    Citation
    (Scopus)
  • Theoretical modeling of photo-induced wave propagation in liquid-crystalline Langmuir monolayers

    T Okuzono, Y Tabe, H Yokoyama

    COLLOIDS AND SURFACES B-BIOINTERFACES   38 ( 3-4 ) 115 - 119  2004.11  [Refereed]

     View Summary

    A phenomenological model of wave propagation in photo-excited liquid-crystal line Langmuir monolayers is constructed. The spontaneous splay deformation of the liquid-crystalline order and the anisotropy of photo-excitation of molecules are taken into account in this model. Numerical simulations of the model well reproduce qualitative features of the wave propagation phenomenon observed in recent experiments. A linear stability analysis of the model equations reveals that an interplay between the spontaneous splay deformation and the anisotropy of the photo-excitation can lead to the wave propagation. (C) 2004 Elsevier B.V. All rights reserved.

    DOI PubMed

    Scopus

    4
    Citation
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  • Generation, propagation, and switching of orientational waves in photoexcited liquid-crystalline monolayers.

    Okuzono T, Tabe Y, Yokoyama H

    Physical review. E, Statistical, nonlinear, and soft matter physics   69 ( 5 Pt 1 ) 050701  2004.05  [Refereed]

    DOI PubMed

    Scopus

    1
    Citation
    (Scopus)
  • Generation, propagation, and switching of orientational waves in photoexcited liquid-crystalline monolayers

    T Okuzono, Y Tabe, H Yokoyama

    PHYSICAL REVIEW E   69 ( 5 )  2004.05  [Refereed]

     View Summary

    Photoinduced orientational waves in illuminated liquid-crystalline monolayers is one of the most remarkable far-from-equilibrium phenomena that systems of soft condensed matter exhibit. We model this behavior from a phenomenological point of view, taking the anisotropic photoexcitation of molecules into account. Numerical simulations as well as theoretical analyses of the model reveal that the intricate interplay between the spontaneous splay deformation of the liquid-crystalline order and the anisotropy of the photoexcitation can lead to the generation and propagation of orientational waves. The model can explain all the salient features of the phenomenon-in particular, the anomalous reversal of the propagation direction upon 90degrees rotation of the polarization direction of illumination, which evaded theoretical explanation for nearly a decade.

    DOI

    Scopus

    1
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    (Scopus)
  • Molecular dynamics simulations of smectic C phase appearing in Langmuir monolayers

    KM Aoki, Y Tabe, T Yamamoto, M Yoneya, H Yokoyama

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   413 ( 1 ) 2287 - 2295  2004  [Refereed]

     View Summary

    We perform molecular dynamics simulations using a simple model system of liquid crystal substance on air-water interface. A system of soft spherocylinders, which do not show smectic C phase in bulk, exhibits a tilted smectic phase when interacting with a model water plane. We observe not only macroscopic properties such as the pressure-surface area curve, but also correlation functions and diffusions as well.

    DOI

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    1
    Citation
    (Scopus)
  • Modeling of nonequilibrium pattern formation in chiral liquid crystal monolayers

    Okuzono Tohru, Tabe Yuka, Yokoyama Hiroshi

    Proceedings of Japanese Liquid Crystal Society Annual meeting   2004   131 - 131  2004

     View Summary

    We construct a simple phenomenological model of collective molecularrotation in chiral liquid crystal monolayers, regarding it as a 2Danalogue of Lehmann-type rotation. Results of numerical simulationsbased on this model are consistent with the experimental observationqualitatively, especially the winding/unwinding phenomena near theboundaries (defect lines, walls).

    DOI CiNii

  • Condensed molecular motor with chiral propeller

    Tabe Yuka, Yokoyama Hiroshi

    Proceedings of Japanese Liquid Crystal Society Annual meeting   2004   132 - 132  2004

     View Summary

    Chiral LC monolayers on glycerol surface exhibit unidirectional precession motion driven by transmembrane water tranport. The rotational speed linearly depends on both molecular chirality and mass of water transfer. The result gives a new approach to molecular motor.

    DOI CiNii

  • Generation, propagation, and switching of orientational waves in photoexcited liquid-crystalline monolayers

    Tohru Okuzono, Yuka Tabe, Hiroshi Yokoyama

    Physical Review E - Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics   69 ( 5 ) 4  2004  [Refereed]

     View Summary

    Photoinduced orientational waves in illuminated liquid-crystalline monolayers is one of the most remarkable far-from-equilibrium phenomena that systems of soft condensed matter exhibit. We model this behavior from a phenomenological point of view, taking the anisotropic photoexcitation of molecules into account. Numerical simulations as well as theoretical analyses of the model reveal that the intricate interplay between the spontaneous splay deformation of the liquid-crystalline order and the anisotropy of the photoexcitation can lead to the generation and propagation of orientational waves. The model can explain all the salient features of the phenomenon—in particular, the anomalous reversal of the propagation direction upon [Formula presented] rotation of the polarization direction of illumination, which evaded theoretical explanation for nearly a decade. © 2004 The American Physical Society.

    DOI

    Scopus

    1
    Citation
    (Scopus)
  • Molecular dynamics simulations of smectic c phase appearing in langmuir monolayers

    Keiko M. Aoki, Yuka Tabe, Takahiro Yamamoto, Makoto Yoneya, Hiroshi Yokoyama

    Molecular Crystals and Liquid Crystals   413   151 - 159  2004  [Refereed]

     View Summary

    We perform molecular dynamics simulations using a simple model system of liquid crystal substance on air-water interface. A system of soft spherocylinders, which do not show smectic C phase in bulk, exhibits a tilted smectic phase when interacting with a model water plane. We observe not only macroscopic properties such, as the pressure-surface area curve, but also correlation functions and diffusions as well.

    DOI

    Scopus

    1
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  • Molecular dynamics simulations of liquid crystal molecules at an air-water interface

    Makoto Yoneya, Keiko M. Aoki, Yuka Tabe, Hiroshi Yokoyama

    Molecular Crystals and Liquid Crystals   413   161 - 169  2004  [Refereed]

     View Summary

    Molecular dynamics simulations were done for terminally alkyl and alkoxy substituted azobenzene liquid crystal (LC) molecules at an air-water interface using realistic (LC and water) molecular models. The simulation result were compared with those of a corresponding amphiphilic modification, i.e. terminal ω-carboocyalkoxy substituted azobenzene. Comparison with a LC with a different mesogen core, phenylpyrimidine, was also made. The interaction energetics were found to be more or less similar both in the alkyl and alkoxy terminated azobenzene and its amphiphilic modification, i.e. cohesive energy dominated over adhesive energy. In contrast, a large difference was found between alkyl and alkoxy terminated azobenzene and phenylpyrimidine LCs
    cohesive and adhesive energy contributions were competitive in the latter molecule.

    DOI

    Scopus

    5
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    (Scopus)
  • Molecular dynamics simulations of liquid crystal molecules at an air-water interface

    M Yoneya, KM Aoki, Y Tabe, H Yokoyama

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   413   2297 - 2305  2004  [Refereed]

     View Summary

    Molecular dynamics simulations were done for terminally alkyl and alkoxy substituted azobenzene liquid crystal (LC) molecules at an air-water interface using realistic (LC and water) molecular models. The simulation result were compared with those of a corresponding amphiphilic modification, i.e. terminal omega-carboxyalkoxy substituted azobenzene. Comparison with a LC with a different mesogen core, phenylpyrimidine, was also made. The interaction energetics were found to be more or less similar both in the alkyl and alkoxy terminated azobenzene and its amphiphilic modification, i.e. cohesive energy dominated over adhesive energy. In contrast, a large difference was found between alkyl and alkoxy terminated azobenzene and phenylpyrimidine LCs; cohesive and adhesive energy contributions were competitive in the latter molecule.

    DOI

    Scopus

    5
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    (Scopus)
  • Photo-induced wave propagation in Langmuir monolayers

    T Okuzono, Y Tabe, H Yokoyama

    SLOW DYNAMICS IN COMPLEX SYSTEMS   708   450 - 451  2004  [Refereed]

     View Summary

    A phenomenological model of photo-induced wave propagation in liquid-crystalline Langmuir monolayers is constructed. The effects of the spontaneous splay deformation of liquid crystal order and the anisotropic photo-excitation of molecules are taken into consideration in this model. Most of qualitative features of the phenomenon are successfully explained by numerical simulations and theoretical analyses of the model.

  • Anisotropy of alkyl chains of azobenzene molecules at the air/water interface observed by sum-frequency vibrational spectroscopy

    M Oh-e, Y Tabe, H Yokoyama

    PHYSICAL REVIEW E   68 ( 6 ) 061602  2003.12  [Refereed]

     View Summary

    Surface-specific sum-frequency vibrational spectroscopy has been used to study the structure of alkyl chains of azobenzene molecules at the air/water interface. The results show that the alkyl chains are well aligned before UV irradiation and protruding out of the surface with a certain distribution. Although the alkyl chains become less ordered by UV irradiation following dynamical motion due to cis-trans isomerization of the azobenzene core, the alkyl chains show anisotropy in the direction perpendicular to that of the azobenzene core by linearly polarized UV irradiation.

    DOI

    Scopus

  • Coherent collective precession of molecular rotors with chiral propellers

    Y Tabe, H Yokoyama

    NATURE MATERIALS   2 ( 12 ) 806 - 809  2003.12  [Refereed]

     View Summary

    Successful attempts to manufacture synthetic molecular motors have recently been reported(1,2). However, compared with natural systems such as motor proteins(3-6), synthetic motors are smaller molecules and are therefore subject to thermal fluctuations that prevent them from performing any useful function(7). A mechanism is needed to amplify the single molecular motion to such a level that it becomes distinguishable from the thermal background. Condensation of molecular motors into soft ordered phases ( such as liquid crystals) will be a feasible approach, because there is evidence that they support molecularly driven non-equilibrium motions(8-10). Here we show that a chiral liquid-crystalline monolayer spread on a glycerol surface acts as a condensed layer of molecular rotors, which undergo a coherent molecular precession driven by the transmembrane transfer of water molecules. Composed of simple rod-like molecules with chiral propellers, the monolayer exhibits a spatiotemporal pattern in molecular orientations that closely resembles 'target patterns' in Belousov-Zhabotinsky reactions(11). Inversion of either the molecular chirality or the transfer direction of water molecules reverses the rotation direction associated with switching from expanding to converging target patterns. Endowed only with the soft directional order, the liquid crystal is an optimal medium that helps molecular motors to manifest their individual motions collectively.

    DOI PubMed

    Scopus

    114
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  • Photo-induced travelling waves in condensed Langmuir monolayers

    Y Tabe, T Yamamoto, H Yokoyama

    NEW JOURNAL OF PHYSICS   5 ( 5 ) 65.1 - 65.11  2003.06  [Refereed]

     View Summary

    We report the detailed properties of photo-induced travelling waves in liquid crystalline Langmuir monolayers composed of azobenzene derivatives. When the monolayer, in which the constituent rodlike molecules are coherently tilted from the layer normal, is weakly illuminated to undergo the trans-cis photo-isomerization, spatio-temporal periodic oscillations of the molecular azimuth begin over the entire excited area and propagate as a two-dimensional orientational wave. The wave formation takes place only when the film is formed at an asymmetric interface with broken up-down symmetry and when the chromophores are continuously excited near the long-wavelength edge of absorption to induce repeated photo-isomerizations between the trans and cis forms. Under proper illumination conditions, Langmuir monolayers composed of a wide variety of azobenzene derivatives have been confirmed to exhibit similar travelling waves with velocity proportional to the excitation power irrespective of the degree of amphiphilicity. The dynamics can be qualitatively explained by the modified reaction-diffusion model proposed by Reigada, Sagues and Mikhailov.

  • Ferroelectric nematic monolayer

    Y Tabe, T Yamamoto, Nishiyama, I, M Yoneya, H Yokoyama

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS   42 ( 4B ) L406 - L409  2003.04  [Refereed]

     View Summary

    Ferroelectricity is desirable for realizing fast-response liquid crystal devices. Existing ferroelectric liquid crystals are improper with the spontaneous polarization Ps being indirectly induced by the broken centrosymmetry of molecular arrangement. We found that Langmuir monolayers of certain dialkylated nematic compound exhibit a laterally polarized two-dimensional ferroelectric nematic. The Ps is comparable to that of chiral smectic. liquid crystals, and shows a fast linear electro-optic switching with a microsecond response. Estimates of electrostatic energy suggest that the ferroelectricity may be driven by the direct dipolar interactions.

    DOI

  • 1A09 Layer by layer growth of tilted smectics : from monolayer to multilayer

    Tabe Yuka, Nishiyama Isa, Yokoyama Hiroshi

    Proceedings of Japanese Liquid Crystal Society Annual meeting   2003   25 - 26  2003

     View Summary

    Dialkyl-terminated smectic compounds can spontaneously spread on water surface and form stable thin films at the bulk LC temperature. Unlike the most amphiphilic Langmuir monolayers, the hydrophobic LC films undergo the layer-by-layer growth under 2D compression, from monolayer to multilayer. In the growth process, there appear some remarkable orientational structures accompanied by a point defect, which directly reveals the relation between inter-layer orientational correlation, surface anchoring and intra-layer elasticity of typical SmC phase.

    DOI CiNii

  • 3C17 A phenomenological model of photo-excited wave propagation in liquid-crystalline Langmuir monolayers

    Okuzono Tohru, Tabe Yuka, Yokoyama Hiroshi

    Proceedings of Japanese Liquid Crystal Society Annual meeting   2003   289 - 290  2003

     View Summary

    A phenomenological model of wave propagation in illuminated Langmuir monolayers is constructed. Numerical simulations and theoretical analyses of this model reveal that an interplay between the spontaneous splay deformation and the anisotrpoic photo-excitation leads to the wave propagation. This model well reproduces all the qualitative features of the phenomenon.

    DOI CiNii

  • Anisotropy of alkyl chains of azobenzene molecules at the air/water interface observed by sum-frequency vibrational spectroscopy

    Masahito Oh-e, Yuka Tabe, Hiroshi Yokoyama

    Physical Review E - Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics   68 ( 6 )  2003  [Refereed]

     View Summary

    Surface-specific sum-frequency vibrational spectroscopy has been used to study the structure of alkyl chains of azobenzene molecules at the air/water interface. The results show that the alkyl chains are well aligned before UV irradiation and protruding out of the surface with a certain distribution. Although the alkyl chains become less ordered by UV irradiation following dynamical motion due to cis-trans isomerization of the azobenzene core, the alkyl chains show anisotropy in the direction perpendicular to that of the azobenzene core by linearly polarized UV irradiation. © 2003 The American Physical Society.

    DOI

    Scopus

  • Can hydrophobic oils spread on water as condensed Langmuir monolayers?

    Yuka Tabe, Takahiro Yamamoto, Isa Nishiyama, Keiko M. Aoki, Makoto Yoneya, Hiroshi Yokoyama

    Journal of Physical Chemistry B   106 ( 47 ) 12089 - 12092  2002.11  [Refereed]

     View Summary

    In contrast to the long-held belief that only amphiphilic molecules can form stable Langmuir monolayers, we show here that even nonvolatile hydrophobic oils can be reversibly spread into liquid-condensed Langmuir films, if the material is in or close to liquid-crystal phase in the bulk. The stability origin of the hydrophobic Langmuir monolayers is entropic, rather than energetic as in the stabilization of common amphiphilic monolayers, primarily driven by the interaction between the polar head and water. This extraordinary spreading mechanism may have impact on the nature of colloidal and biomembrane stabilities.

    DOI

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    20
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  • Can hydrophobic oils spread on water as condensed Langmuir monolayers?

    Y Tabe, T Yamamoto, Nishiyama, I, KM Aoki, M Yoneya, H Yokoyama

    JOURNAL OF PHYSICAL CHEMISTRY B   106 ( 47 ) 12089 - 12092  2002.11  [Refereed]

     View Summary

    In contrast to the long-held belief that only amphiphilic molecules can form stable Langmuir monolayers, we show here that even nonvolatile hydrophobic oils can be reversibly spread into liquid-condensed Langmuir films, if the material is in or close to liquid-crystal phase in the bulk. The stability origin of the hydrophobic Langmuir monolayers is entropic, rather than energetic as in the stabilization of common amphiphilic monolayers, primarily driven by the interaction between the polar head and water. This extraordinary spreading mechanism may have impact on the nature of colloidal and biomembrane stabilities.

    DOI

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    20
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  • 3B03 Ferroelectric Nematic Monolayer

    Tabe Yuka, Yamamoto Takahiro, Nishiyama Isa, Yoneya Makoto, Yokoyama Hiroshi

    Proceedings of Japanese Liquid Crystal Society Annual meeting   2002   231 - 232  2002

     View Summary

    A certain dialkylated achiral thermotropic nematic compound was found to exhibit a two-dimensional ferroelectric nematic, when spread on the water surface as a Langmuir monolayer. The monolayer has a larger spontaneous polarization than DOBAMBC, and shows a fast electro-optic switching with a microsecond response time under a low electric field.

    DOI CiNii

  • Near-critical two-dimensional smectic-C to solid-like phase transition in azobenzene-derivative Langmuir monolayers

    Y Tabe, H Yokoyama

    JOURNAL OF CHEMICAL PHYSICS   115 ( 2 ) 1041 - 1051  2001.07  [Refereed]

     View Summary

    We describe the results of a detailed study of two-dimensional (2D) smectic-C to solid-like phase transition in azobenzene-derivative Langmuir monolayers by the surface pressure vs area-per-molecule isotherm measurement, polarizing optical microscopy, and the grazing incidence synchrotron x-ray diffraction. The phase transition was observed to be weakly first order up to slightly above room temperature with a transition entropy less than 1.0 k(B) per molecule, accompanied by proper characteristics of a nearly ideal horizontal coexistence line on the isotherm, an abrupt change in optical texture, and the emergence of a conspicuous x-ray diffraction peak in the solid-like phase, which indicates a weak positional order with a correlation length of 10-20 nm. Analysis of the x-ray diffraction data within the framework of distorted hexagonal lattice suggests that the solid-like phase may be regarded as a 2D analog of smectic-L phase that is a hexatic smectic phase with the molecules tilted toward a direction between the nearest and the next-nearest bonds. At higher temperatures, the transition became less discontinuous and entirely disappeared above 40 degreesC in all these experimental aspects. We argue that the transition is viewed as a 2D induced hexatic-hexatic transition (analog of smectic-C to smectic-L transition), which has an isolated critical point where the first-order transition comes to an end. (C) 2001 American Institute of Physics.

    DOI

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    11
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  • Liquid crystal-water interactions in Langmuir monolayers.

    Yoneya Makoto, Aoki Keiko M., Tabe yuka, Yokoyama Hiroshi

    Proceedings of Japanese Liquid Crystal Society Annual meeting   2001   185 - 186  2001

     View Summary

    Some thermotropic liquid crystal molecules are known as they can form stable Langmuir monolayers on air-water interface. However, prerequisites for formation of such a Langmuir monolayer are not well understood yet except some molecules (e.g. cyano-biphenyl derivatives). We apply a molecular simulation approach to study this subject with special attentions on the liquid crystal - water interactions in the Langmuir monolayers.

    DOI CiNii

  • Two-dimensional Isotropic-SmC phase transition in Langmuir monolayers

    Tabe yuka, Nishiyama Isa, Yoneya Makoto, Aoki Keiko M., Yokoyama Hiroshi

    Proceedings of Japanese Liquid Crystal Society Annual meeting   2001   183 - 184  2001

     View Summary

    Two-dimensional Isotropic-Smectic C phase transition is observed for the first time in Langmuir monolayers composed of dialkyl-terminated thermotropic LC compound. Under the 2D compression, the monolayers exhibit the first-order phase transition from isotropic fluid, where the constituent molecules lie down on the water surface, to the 2D SmC phase. The transition is completely reversible with a clean indication the SmC order induced by the 2D compression in the monomolecular films.

    DOI CiNii

  • Molecular dynamics simulation of Langmuir layers

    Aoki Keiko M., Tabe yuka, Yoneya Makoto, Yokoyama Hiroshi

    Proceedings of Japanese Liquid Crystal Society Annual meeting   2001   187 - 188  2001

     View Summary

    Molecular dynamics simulations of simple models of Langmuir layers are conducted. Softcore spherocylinders interacting via repulsive interaction along with simple force models of water-molecule interaction give rise to SmC phase (titled phase) layer. This suggests that SmC layers can appear in substance without thermotropically stable SmC phase in bulk. Simulation results also suggest that SmC layers might appear in the temperature range where nematic LC is stable in bulk, Dynamics as well as microscopic properties are reported.

    DOI CiNii

  • Simulation studies of Langmuir monolayers

    KM Aoki, Y Tabe, H Yokoyama

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   367   2979 - 2986  2001  [Refereed]

     View Summary

    It has been shown experimentally that molecules, which exhibit liquid crystal phases in bulk, also show interesting phenomena when they are formed in monolayers at air-water interface. The purpose of this work is to clarify to what extent can a simple model explain the complicated behavior of such Langmuir monolayers. Molecular dynamic simulation is conducted to observe the phase and dynamics of Langmuir monolayers.

  • Photoisomerization-induced orientational wave generation in two-dimensional liquid crystals at the air-water interface

    Y Tabe, H Yokoyama

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   358   125 - 137  2001  [Refereed]

     View Summary

    Certain class of amphiphilic derivatives of azobenzene form a stable monolayer analog of single-layer smectic-C (SmC) phase at the air-water interface. Due to the broken up-down symmetry, this two-dimensional liquid crystal shows intriguing static orientation structures such as the stripe and higher-order point defects in equilibrium. We found that weak excitation of isomerization reaction of azobenzene core results in a persistent generation of orientational waves and solitons propagating in the plane of the monolayer. This is the first example of purely light-driven nonequilibrium pattern formation. Analysis of the static structures has revealed the essential significance of the coupling between the orientational order and molecular density. Although no definite explanation as yet exists for the dynamic behavior, we believe the density-orientation coupling should play an important role.

  • Tilted Smectic Phases in Langmuir Monolayers

    Tabe Yuka, Nishiyama Isa, Yokoyama Hiroshi

    Proceedings of Japanese Liquid Crystal Society Annual meeting   2000   77 - 78  2000

     View Summary

    New tilted smectic phases in Langmuir monolayers composed of FLC materials are reported in this paper. We found a mixture of several FLC materials take 2D SmC phase on the water surface at room temperature, showing similar schlieren texture to bulk SmC and nematics. Under compression, unlike the ordinary Langmuir monolayers, the film exhibits first-order monolayer-by-monolayer growth of the film thickness on the water surface, eventually resulting in multilayer-structures instead of collapsing.

    DOI CiNii

  • In-plane polar structure in 2D liquid crystalline monolayers probed by optical second harmonic generation spectroscopy

    Y Tabe, H Yokoyama

    STATISTICAL PHYSICS   519   133 - 139  2000  [Refereed]

     View Summary

    The alleged in-plane polar structure in two-dimensional (2D) smectic-C liquid crystalline phases of Langmuir monolayers was directly confirmed by the optical second harmonic generation (SHG) spectroscopy for the first time. The SH signal associated with the in-plane polar structure was found to be comparable with that coming from the out-of-plane polar distribution of molecular orientation inherent at the air-water interface, This result indicates that there exits a strong preference for the heads and tails of the molecules to spontaneously associate one another over the otherwise isotropic water surface as a result of the 2D liquid crystalline order. When the monolayer underwent a first order phase transition from SmC to a solid-like phase under compression, both of the in-plane and out-of-plane components of SH signals were considerably reduced despite an increase in density, implying the rather subtle nature of the centro-symmetry breaking in the SmC phase.

  • Simultaneous observation of molecular tilt and azimuthal angle distributions in spontaneously modulated liquid-crystalline Langmuir monolayers

    Y Tabe, N Shen, E Mazur, H Yokoyama

    PHYSICAL REVIEW LETTERS   82 ( 4 ) 759 - 762  1999.01  [Refereed]

     View Summary

    We carried out the first quantitative measurements of correlated modulations of molecular tilt and azimuthal angles in two-dimensional smectic-C Langmuir monolayers using simultaneous linear- and circular-polarized reflected light microscopy. For spontaneously formed stripes and higher-order point defects, the tilt angle varies nearly sinusoidally at twice the spatial frequency of the azimuthal rotation. The tilt modulation grows as the second power of the modulation wave number and leads to a large escaped core for the point defect. Our results can be explained by an extended Landau theory of tilted smectics.

    DOI

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    45
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  • Simultaneous Observation of Molecular Tilt and Azimuthal Angles in Two-dimensional Liquid Crystalline Langmuir Monolayers

    Tabe Yuka, Yokoyama Hiroshi

    Proceedings of Japanese Liquid Crystal Society Annual meeting   1998   504 - 505  1998

     View Summary

    Simultaneous use of linear- and circular-polarizing reflected light microscopes allowed first quantitative observation of correlated modulations of molecular tilt and azimuthal angles in two-dimensional (2D) smectic-C Langmuir monolayers. For spontaneously formed stripes and higher-order point defects, the tilt angie varied nearly sinusoidally with twice the spatial frequency of the continuous azimuthal rotation. The tilt modulation grew as the second power of the modulation wavenumber and led to a large escaped core for point defects. These results can be consistently explained by an extended Landau theory of tilted smectics.

    DOI CiNii

  • Phenomenological Theory of Photo-induced Reorientation in Liquid Crystals and its Experimental Verification

    YOKOYAMA Hiroshi, TABE Yuka

    Proceedings of Japanese Liquid Crystal Society Annual meeting   1998   506 - 507  1998

     View Summary

    We have developed a phenomenological order-parameter theory of photo-induced reorientation in liquid crystals. With an assumption of rapid rotational diffusion of photo-excited molecules, the effective photo-induced torque on the director has been formulated in a simple closed form in terms only of the tensor order parameters of the ground state and excited dye molecules. In particular, the torque is proportional to the difference of these order parameters and, accordingly, changes sign depending on the relative magnitude of the order parameters. Illumination effect on the Freedericksz transition is proposed to be a convenient experimental scheme to quantitatively study the reorientation behavior. Supporting experimental demonstration will be presented.

    DOI CiNii

  • Orientational fluctuations in a two-dimensional smectic-C liquid crystal with variable density

    A Feder, Y Tabe, E Mazur

    PHYSICAL REVIEW LETTERS   79 ( 9 ) 1682 - 1685  1997.09  [Refereed]

     View Summary

    We studied orientational fluctuations in a smectic-C Langmuir monolayer. Our measurements of orientational correlations are in excellent agreement with theoretical predictions. In addition, we present the first measurements of orientational elasticity and viscosity in a two-dimensional system whose density can be varied. The orientational viscosity strongly depends on temperature and density, changing by more than an order of magnitude with a 2.5% increase in temperature or a 20% change in density. The orientational elasticity is only weakly dependent on temperature and density.

    DOI

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    17
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  • Two-dimensional dynamic patterns in illuminated Langmuir monolayers

    Y Tabe, H Yokoyama

    LANGMUIR   11 ( 12 ) 4609 - 4613  1995.12  [Refereed]

     View Summary

    Purely light-driven spatiotemporal pattern formation has been found to take place in a liquid-crystalline Langmuir monolayer consisting of an amphiphilic azobenzene derivative, undergoing the trans &lt;----&gt; cis photoisomerizations. The Langmuir monolayer is in a smectic-C-like liquid crystal phase, whose two-dimensional orientation is easily perturbed by slight conformation changes in the constituent molecules. On illumination with a linearly polarized light, a collective and global in-plane reorientation of the azobenzene chromophores is induced over an existing static stripe texture, which finally yields polarization-dependent steady state orientational patterns. Prolonged photoexcitation generates sustained traveling and solitary waves, associated with variations in molecular tilt directions. The liquid crystallinity of the monolayer allows these orientational responses to occur even at an extremely weak light power at least 2 orders of magnitude smaller than that known in previous photoreorientation studies of azobenzene chromophores.

    DOI

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    64
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    (Scopus)
  • FRESNEL FORMULA FOR OPTICALLY ANISOTROPIC LANGMUIR MONOLAYERS - AN APPLICATION TO BREWSTER-ANGLE MICROSCOPY

    Y TABE, H YOKOYAMA

    LANGMUIR   11 ( 3 ) 699 - 704  1995.03  [Refereed]

     View Summary

    An approximate yet highly accurate Fresnel formula, describing the reflection from optically anisotropic Langmuir monolayers, is derived in a simple closed form. The utility of the Fresnel formula is demonstrated by an application to Brewster angle microscopy.

    DOI

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    39
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  • NOVEL LIQUID-CRYSTALLINE STRUCTURE IN LANGMUIR MONOLAYERS OF AMPHIPHILIC AZOBENZENE DERIVATIVE

    Y TABE, H YOKOYAMA

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   63 ( 7 ) 2472 - 2476  1994.07  [Refereed]

     View Summary

    Depolarized Brewster-angle microscopy revealed a novel two-dimensional (2D) mesophase in Langmuir monolayers of 4-octyl-4'-(3-carboxytrimethyleneoxy) azobenzene, characterized by ubiquitous schlieren textures resulting from the long-range order of in-plane molecular orientations. The lack of half-integral strength disclinations and the presence of a regular array of pi-walls, across which the in-plane orientation changes by 180 degrees, indicate the vectorial nature of the underlying order parameter. The monolayer can, therefore, be viewed as a single layer of a bulk smectic C phase or as a 2D polar nematic phase, except for the obvious absence of mirror symmetry with respect to the layer plane. In contrast to the experience with bulk liquid crystalline phases, higher-order point disclinations were often found stable in the monolayer.

    DOI

  • ALIGNMENT OF SURFACE-STABILIZED FERROELECTRIC LIQUID-CRYSTAL BY THE SELF-ASSEMBLED MONOLAYERS OF AMPHIPHILIC DIACETYLENE DERIVATIVES

    T TANAKA, Y HONDA, T TANI, A TERAHARA, Y TABE, M SUGI

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   33 ( 1A ) 295 - 301  1994.01  [Refereed]

     View Summary

    Surface-stabilized ferroelectric liquid crystal was aligned by the self-assembled monolayers (SAMs) of amphiphilic diacetylene derivatives formed on an indium tin oxide/glass substrate to maintain bistability when ferroelectric liquid crystal with high spontaneous polarization was used. The SAMs were disposed uniaxially either after rubbing them or passing them through a meniscus at a three-phase contact between a substrate, air, and n-hexane before exposing them to ultra-violet (UV) light. Infrared transmission spectra, contact angles against water and time of flight secondary ion mass spectra have revealed that the modified surface was a sparse monolayer of the diacetylenes, and that they were polymerized by UV light.

    DOI

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    5
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    (Scopus)
  • NUMERICAL-CALCULATION OF FLOW ORIENTATION EFFECTS IN THE LANGMUIR-BLODGETT DEPOSITION PROCESS

    Y TABE, K IKEGAMI, M SUGI

    JOURNAL OF APPLIED PHYSICS   73 ( 2 ) 905 - 913  1993.01  [Refereed]

     View Summary

    The angular distribution function of rodlike particles in Langmuir-Blodgett (LB) films is numerically analyzed. The calculation is based on the integral form of the rotatory diffusion equation and, in contrast with previous analyses, does not assume an instantaneous thermal equilibrium. As each particle keeps memory of the flow history on the water surface, the final distribution function is dependent on the initial conditions of the particle. However, when-the initial point is so far from the substrate that the memory of initial point is almost lost, the final distribution function is approximately determined by the dimensionless number C = (zeta'G+tau0)/2k(B)T, where zeta' is the rotational friction coefficient, tau0 the Bingham yield value, a the substrate width, and nu(d) the dipping velocity of the substrate. The presence of a meniscus region around the substrate should be taken into account. The streamlines between the water surface and the substrate surface are smoothly connected, while assuming a cylindrical shape for the meniscus. The angular distribution function obtained by this numerical calculation is in good agreement with the experimental results for a mixed LB system of merocyanine dye/fatty acid.

    DOI

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    12
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  • ANOMALOUS HYDRODYNAMIC BEHAVIOR OF LYOTROPIC SMECTIC PHASES OF HYDRATED PHOSPHOLIPID AT LOW-FREQUENCIES

    J YAMAMOTO, Y TABE, K OKANO

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS   31 ( 11A ) L1560 - L1562  1992.11  [Refereed]

     View Summary

    We measured the frequency dependence of the longitudinal viscosity and the layer compression modulus of homeotropically aligned multilamellar film of hydrated dimyristoyl phosphatidylcholine (DMPC) at low frequencies from 10 Hz to 1 kHz, varying temperature (T) and relative humidity (RH) systematically. We have, for the first time, demonstrated unambiguously that in the L(alpha) phase (the lyotropic smectic-A phase) the longitudinal viscosity diverges as 1/omega when the circular frequency goes to zero. In addition, we were able to construct the T-RH phase diagram of the L(alpha)-L(beta') transition of hydrated DMPC, based upon the T and RH dependences of the layer compression modulus. The phase boundary thus determined agreed well with that obtained by X-ray scattering by Smith et al. (J. Chem. Phys. 92 (1990) 4519).

  • FLOW ORIENTATION IN LANGMUIR-BLODGETT-FILMS OF A CHARGE-TRANSFER COMPLEX (TMTTF)3(C14TCNQ)2

    K IKEGAMI, S KURODA, Y TABE, K SAITO, M SUGI, M MATSUMOTO, T NAKAMURA, Y KAWABATA

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   31 ( 4 ) 1206 - 1212  1992.04  [Refereed]

     View Summary

    The occurrence of flow orientation during the deposition of Langmuir-Blodgett films of (TMTTF)3(C14TCNQ)2 is shown through studies of in-plane molecular orientation in films deposited by two types of the vertical dipping method, with the substrates parallel and perpendicular to the barrier, using ESR and polarized UV-visible spectroscopies. Larger in-plane anisotropy is observed toward the edge of the substrates, which is consistent with the prediction of the recent theory of flow orientation during the deposition process. Furthermore, in-plane anisotropy in the films deposited by the horizontal lifting method is detected, suggesting the existence of a compression orientation at the air-water interface.

  • ELECTRON-SPIN-RESONANCE IN LANGMUIR-BLODGETT-FILMS OF A MEROCYANINE DYE AND ITS ISOTOPE-SUBSTITUTED ANALOGS

    S KURODA, K IKEGAMI, Y TABE, K SAITO, M SAITO, M SUGI, S YASUI

    THIN SOLID FILMS   210 ( 1-2 ) 512 - 514  1992.04  [Refereed]

     View Summary

    Stable radical species existing in mixed Langmuir-Blodgett films of a merocyanine dye and arachidic acid are studied through their hyperfine couplings using the isotope substitution technique. One of the species shows a nitrogen hyperfine structure possibly arising from one of the two nitrogen sites in the molecule. With the employment of two dye analogs in which either one of the N-14 nuclei is replaced by N-15, the observed nitrogen site has been identified to be the one in benzothiazole. That is, the wave function of the radical is directly associated with the dye chromophore. The photo-induced spectra have shown a similar change as the dark spectra upon N-15-substitution, indicating that the dark and photo-induced signals arise from a common species. These facts together with the recently observed correlation between the anisotropic behaviour of ESR and optical J-band strongly suggest an intermolecular charge transfer in J-aggregates as the origin of radical generation.

  • THEORY OF FLOW ORIENTATION EFFECTS IN LANGMUIR-BLODGETT-FILMS - EXAMINATION OF THE LOCAL THERMAL-EQUILIBRIUM APPROXIMATION

    Y TABE, M SUGI, K IKEGAMI, S KURODA, K SAITO, M SAITO

    THIN SOLID FILMS   210 ( 1-2 ) 32 - 35  1992.04  [Refereed]

     View Summary

    The angular distribution function for the case of one single substrate in a large trough is numerically calculated allowing for the deviation from the local thermal equilibrium. The function obtained for the line-sink potential on the water surface is found to disagree with that of the previous model derived using the local thermal equilibrium approximation. As for the transfer from the water surface to the substrate, two different models are introduced, the abrupt connection and a smooth connection. The smooth connection model leads to a satisfactory agreement with the predictions from the previous model, and, at the same time, to a semi-quantitative coincidence with the experimentally observed dichroic behavior for the previously obtained values of the viscoelastic parameters. These results indicate that the line-sink potential with local thermal equilibrium approximation, if not strictly relevant to the process on the water surface, is effective for describing the angular distribution in LB films.

  • MOLECULAR-ORIENTATION IN CONDUCTIVE LANGMUIR-BLODGETT-FILMS OF A CHARGE-TRANSFER COMPLEX

    K IKEGAMI, S KURODA, Y TABE, K SAITO, M SAITO, M SUGI, T NAKAMURA, H TACHIBANA, M MATSUMOTO, Y KAWABATA

    THIN SOLID FILMS   210 ( 1-2 ) 303 - 305  1992.04  [Refereed]

     View Summary

    The molecular orientation in Langmuir-Blodgett films of a 3:2 charge-transfer complex of tetramethyltetrathiafulvalene and tetradecyltetracyanoquinodimethane [(TMTTF)3(C14TCNQ)2] is discussed from the observed anisotropic ESR spectra at the K and X bands. Anisotropy of g values shows the existence of in-plane preferential orientation of the complex with the p-pi-orbital axis and long axis of the TMTTF molecules parallel and perpendicular to the dipping direction of the substrate, respectively. The effect of aging on ESR spectra of the system is also reported. The decrease in the difference in linewidth at the K and X bands observed for the external magnetic field normal to the film plane indicates the reduction in the degree of misorientation of the molecules by aging.

    DOI

    Scopus

    6
    Citation
    (Scopus)
  • SUBSTITUENT-DEPENDENT SELF-ASSEMBLY - 2-DIMENSIONAL AGGREGATE FORMATION IN CYANINE DYE-ADSORBED LANGMUIR-BLODGETT-FILMS

    K SAITO, K IKEGAMI, S KURODA, Y TABE, M SUGI

    JOURNAL OF APPLIED PHYSICS   71 ( 3 ) 1401 - 1406  1992.02  [Refereed]

     View Summary

    Interface-adsorbed complex Langmuir-Blodgett (LB) films of arachidic acid and water-soluble, mesosubstituted cyanine dyes were fabricated using the diffusion-adsorption method to examine the substituent-dependent self-assembly at the water-monolayer interface. Either a J aggregate or an H aggregate was found to be formed in the LB films depending on the substituent introduced, the ethyl or methyl group. The H aggregate is accompanied by Davydov splitting, which is characterized as the split of the band into two bands, whose transition moments are orthogonal to each other. Measurements of photoluminescence and microscopic spectroscopy were performed to identify the type of the aggregates. The molecular arrangements in the aggregates were estimated based on Davydov's theory and the extended dipole model. Dependence of photoelectric properties of the LB films on the type of aggregates has been studied employing Schottky-type cells.

  • FLOW-ORIENTATION EFFECT IN BATCH-PRODUCED LANGMUIR-BLODGETT-FILMS - OBSERVATION OF THE UNSTEADY-FLOW AROUND THE STAGNATION POINT

    Y TABE, K IKEGAMI, S KURODA, K SAITO, M SAITO, M SUGI

    JOURNAL OF APPLIED PHYSICS   70 ( 3 ) 1425 - 1432  1991.08  [Refereed]

     View Summary

    The in-plane anisotropy of the Langmuir-Blodgett films of a merocyanine-fatty acid mixed system has been further studied for two different cases of batch production with the substrates aligned face to face and side by side, respectively, to clarify the limitations of the flow-orientation model based on the ideal-fluid approximation. For the side-by-side case, satisfactory coincidence is found between the model and experiment. The actual dichroic behavior deviates from that predicted for the face-to-face case with smaller intersubstrate distances. It was speculated that the stagnation point is associated with anomaly in velocity which is responsible for this discrepancy. In order to examine this, the flow of the monolayer on the water surface during the deposition has been observed using sulphur powder as marker in addition to the optical measurements. The actual flow deviates from that expected from the model and is associated with unsteady motion around the stagnation point as previously speculated. It is indicated that the ideal-fluid approximation is inappropriate for the face-to-face case with smaller distances, leading to the prediction inconsistent with the actual dichroic behavior.

    DOI

    Scopus

    5
    Citation
    (Scopus)
  • FORMATION OF HERRINGBONE STRUCTURE WITH DAVYDOV SPLITTING IN CYANINE DYE-ADSORBED LANGMUIR-BLODGETT-FILMS

    K SAITO, K IKEGAMI, S KURODA, Y TABE, M SUGI

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS   30 ( 8 ) 1836 - 1840  1991.08  [Refereed]

     View Summary

    Interface-adsorbed complex Langmuir-Blodgett (LB) films of arachidic acid and a water-soluble cyanine dye were fabricated using the diffusion-adsorption method. Formation of an H-aggregate with absorption band split was observed in the LB film. This split is assignable as Davydov splitting, which is characterized as the split of the band into two bands, whose transition moments are orthogonal to each other, due to formation of herringbonelike aggregates. The estimation of the molecular arrangement in the aggregate was performed based on Davydov's theory and the extended dipole model.

  • MODIFICATION OF AGGREGATE FORMATION IN ARACHIDIC-ACID-CYANINE-DYE COMPLEX LANGMUIR-BLODGETT-FILMS BY SUBSTITUENT GROUPS

    K SAITO, K IKEGAMI, S KURODA, M SAITO, Y TABE, M SUGI

    JOURNAL OF APPLIED PHYSICS   69 ( 12 ) 8291 - 8297  1991.06  [Refereed]

     View Summary

    Water-soluble cyanine dye derivatives can be adsorbed from aqueous solution to an arachidic acid monolayer at the air-water interface. Interface-adsorbed complex Langmuir-Blodgett films of arachidic acid and four different derivatives of thiacarbocyanine dyes were fabricated using this method, and their optical properties were examined employing a linearly polarized incident. Clear differences in both spectral shape and in-plane anisotropy were found among the films of different derivatives, each associated with an aggregate form characteristic of the substituent group. They can be classified as a dimer with Davydov splitting, a monomer, and a J aggregate. Estimation of the configuration of the molecules in the dimers and measurement of the photoluminescence spectrum for the J aggregate were performed to clarify the nature of aggregates. The results suggest the possibility of systematic control of aggregate formation in the system by introducing substituent groups for dyes.

  • KINETICS OF METAL-ION LIBERATION BY ACID TREATMENT IN FATTY-ACID SALT LANGMUIR-BLODGETT-FILMS

    M SAITO, K IKEGAMI, Y TABE, K SAITO, S KURODA, M SUGI

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS   30 ( 3B ) L511 - L513  1991.03  [Refereed]

     View Summary

    The liberation process of metal ions in fatty acid salt LB films soaked in a dilute hydrochloric acid has been studied using X-ray diffraction and IR measurements. The reaction kinetics was found to be described as a pseudomonomolecular reaction. It is suggested that the metal ions, after being liberated from the carboxylate sites, are removed from the film system into the solution.

  • ELECTRON-SPIN-RESONANCE OF STABLE RADICALS IN LANGMUIR-BLODGETT-FILMS OF A MEROCYANINE DYE - STUDY OF HYPERFINE COUPLING USING A N-15-ENRICHED DYE

    S KURODA, K IKEGAMI, Y TABE, K SAITO, M SAITO, M SUGI

    PHYSICAL REVIEW B   43 ( 4 ) 2531 - 2540  1991.02  [Refereed]

     View Summary

    Two kinds of stable radical species exist in mixed Langmuir-Blodgett (LB) films of a merocyanine dye and arachidic acid. One of the species exhibits clear nitrogen hyperfine structure in ESR spectra, which was previously confirmed by measurements at X and Q bands. Use of the N-15-enriched dye derivative clearly identified the hyperfine coupling to arise from the nitrogen nucleus in benzothiazole, which belongs to the chromophore of the dye molecule; N-C = C-C = C-C = O. ESR spectra measured at both X and K bands in unsubstituted and N-15-substituted systems permits the detailed analysis of in-plane molecular orientation using the spectrum-simulation method incorporating three-dimensional freedom of orientation. The analysis of the dependence of the spectra on the substrate position yields the local orientation of the radical molecules, which shows a higher degree of orientation toward the edge of the substrate. This behavior coincides with that of the majority of molecules forming J aggregates, obtained from optical analysis, and is well described by a recent theory of the flow orientation of molecular domains caused during the dipping process of LB films. This coincidence between the orientation of the radicals and J aggregates provides new evidence that stable radicals are generated in the J aggregate. The mechanism of radical generation is discussed in view of our previously proposed model of an intermolecular charge transfer in J aggregates.

  • RANDOM-EXCHANGE HEISENBERG AF CHAINS IN LANGMUIR-BLODGETT-FILMS OF AMPHIPHILIC CHARGE-TRANSFER COMPLEXES

    K IKEGAMI, S KURODA, Y TABE, K SAITO, M SAITO, M SUGI, H TACHIBANA, T NAKAMURA, Y KAWABATA

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   90-1   239 - 240  1990.12  [Refereed]

     View Summary

    ESR measurements were performed on Langmuir-Blodgett (LB) films of 1:2 complex of long-chain pyridinium and TCNQ, where the long chain contains photo-active azobenzene group. Observed temperature dependence of the spin susceptibility is consistent with the formation of the random-exchange Heisenberg antiferromagnetic chains in the system.

    DOI

    Scopus

    8
    Citation
    (Scopus)
  • ACID VAPOR TREATMENT OF FATTY-ACID SALT LB FILMS - EVIDENCE FOR CONSERVATION OF THE LAMELLAR STRUCTURE

    M SAITO, Y TABE, K SAITO, K IKEGAMI, S KURODA, M SUGI

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS   29 ( 10 ) L1892 - L1894  1990.10  [Refereed]

    DOI

    Scopus

    7
    Citation
    (Scopus)
  • DAVYDOV SPLITTING IN ARACHIDIC ACID CYANINE DYE COMPLEX LANGMUIR-BLODGETT-FILMS

    K SAITO, K IKEGAMI, S KURODA, M SAITO, Y TABE, M SUGI

    JOURNAL OF APPLIED PHYSICS   68 ( 5 ) 1968 - 1974  1990.09  [Refereed]

    DOI

    Scopus

    18
    Citation
    (Scopus)
  • INPLANE ANISOTROPY IN BATCH-PRODUCED LANGMUIR-BLODGETT-FILMS - SIDE-BY-SIDE AND FACE-TO-FACE ARRAYS

    Y TABE, K IKEGAMI, S KURODA, K SAITO, M SAITO, M SUGI

    APPLIED PHYSICS LETTERS   57 ( 12 ) 1191 - 1193  1990.09  [Refereed]

    DOI

    Scopus

    5
    Citation
    (Scopus)
  • Present Status of the Research on LB Films

    TABE Yuka, KURODA Shin-ichi, SUGI Michio

    Journal of the Japan Society of Precision Engineering   56 ( 3 ) 473 - 477  1990.03

    DOI CiNii

    Scopus

▼display all

Presentations

  • Unidirectional Molecular Rotations of Chiral and Achiral Liquid Crystals Driven by Linear Flows

    TABE, Yuka  [Invited]

    OKINAWA COLLOIDS 2019 

    Presentation date: 2019.11

  • Rigid-body Rotations of Chiral and Achiral Liquid Crystalline Droplets Driven by Linear Fluxes

    TABE, Yuka  [Invited]

    Soft Matter Physics: from the perspective of the essential heterogeneity 

    Presentation date: 2018.12

  • A thermomechanical coupling in cholesteric liquid crystals

    TABE, Yuka  [Invited]

    13th International Meeting on Thermodiffusion 

    Presentation date: 2018.09

  • Rotation of Non-chiral Soft Crystal by Electron Beam Irradiation

    TABE, Yuka  [Invited]

    Toyota Riken International Workshop on Chirality in Soft Matter 

    Presentation date: 2017.11

  • Unidirectional Rotation of an Achiral Soft Crystal Driven by Low-energy Electron-beam

    TABE, Yuka  [Invited]

    Chirality 2017: ISCD-29 

    Presentation date: 2017.07

  • Flow-driven rotations of achiral 2D crystals and chiral nematic droplets embedded in liquid films

    TABE, Yuka  [Invited]

    26th International Liquid Crystal Conference 2016 

    Presentation date: 2016.07

  • Unidirectional director rotation in chiral liquid crystals under heat and mass fluxes

    TABE, Yuka  [Invited]

    Chirality at the Nanoscale Symposium 

    Presentation date: 2015.06

  • Heat-driven unidirectional rotation of cholesteric LC droplets

    TABE, Yuka  [Invited]

    7th Italian-Japanese Workshop on Liquid Crystals 

    Presentation date: 2014.07

  • Dynamical Cross Correlation in Chiral Liquid Crystals

    TABE, Yuka  [Invited]

    The 7th International Conference Engineering of Chemical Complexity 

    Presentation date: 2013.06

  • Orientational and Hydrodynamic Motions in Chiral Liquid Crystalline Films Induced by Transmembrane Vapor Transfer

    TABE, Yuka  [Invited]

    The 24th International Liquid Crystal Conference 

    Presentation date: 2012.08

  • Smectic Bubbles

    TABE, Yuka  [Invited]

    Optics & Photonics SPIE 

    Presentation date: 2012.01

  • Dynamical Cross-coupling in Chiral Liquid Crystals

    TABE, Yuka  [Invited]

    Gordon Research Conference (Liquid Crystals) 

    Presentation date: 2011.06

  • Anomalous Deformation of Smectic Liquid Crystal Bubbles under DC Electric Field

    TABE, Yuka  [Invited]

    The 5th Italian-Japanese Workshop on Liquid Crystals 

    Presentation date: 2010.07

  • Possible Nanomachine Made of Chiral Liquid Crystals

    TABE, Yuka  [Invited]

    Optics & Photonics SPIE 

    Presentation date: 2009.08

  • Flow-induced Nonlinear Dynamics in Two-dimensional Liquid Crystals

    TABE, Yuka  [Invited]

    9th European Conference on Liquid Crystals 

    Presentation date: 2007.07

  • LC molecular motor

    TABE, Yuka  [Invited]

    Gordon Research Conferences 

▼display all

Research Projects

  • カイラル液晶分子の集団回転による一方向熱輸送

    日本学術振興会  科学研究費助成事業

    Project Year :

    2022.04
    -
    2025.03
     

    多辺 由佳

Misc

  • 液晶 : 固体で液体 : 第4の相

    多辺 由佳

    現代化学 = Chemistry today   ( 557 ) 21 - 25  2017.08

    CiNii

  • Director/Barycentric Rotation in Cholesteric Droplets under Temperature Gradient

    Jun YOSHIOKA, Yuka TABE

    液晶 : 日本液晶学会誌 : journal of the Japanese Liquid Crystal Society   20 ( 1 ) 27 - 34  2016.01  [Refereed]  [Invited]

    Article, review, commentary, editorial, etc. (scientific journal)  

    CiNii

  • 30aPS-130 Heat-driven rotations in 3 types of cholesteric droplets

    Ito Fumiya, Yoshioka Jun, Tabe Yuka

    Meeting abstracts of the Physical Society of Japan   69 ( 1 ) 430 - 430  2014.03

    CiNii

  • 30aPS-131 Spontaneous periodic deformation of cholesteric-isotropic interface

    Takizawa Hideaki, Yoshioka Jun, Tabe Yuka

    Meeting abstracts of the Physical Society of Japan   69 ( 1 ) 430 - 430  2014.03

    CiNii

  • 28pBD-7 The structures of liquid crystalline Langmuir films, the role of the fluctuation

    Tabe Yuka

    Meeting abstracts of the Physical Society of Japan   69 ( 1 ) 340 - 340  2014.03

    CiNii

  • Physics of liquid crystals

    Yuka Tabe, Kenji Urayama, Akihiko Matsuyama, Jun Yamamoto, Makoto Yoneya

    The Liquid Crystal Display Story: 50 Years of Liquid Crystal R and D that Lead the Way to the Future     301 - 356  2014.01

     View Summary

    © Springer Japan 2014 Over the 100 years since its discovery, liquid crystals have been the intriguing subject for both academia and industries. The textbook of de Gennes The Physics of Liquid Crystals published in 1974 is still the bible for many LC researchers, but new subjects unmentioned in the book have also risen for these years. This chapter describes the story of the recent developments and the future perspectives in physics of liquid crystals, especially focusing on the contributions by Japanese research groups for the last decade.

    DOI

  • Dynamic cross correlation in cholesteric droplets with stripe textures

    Yoshioka Jun., Suzuki Yuto, Takahashi Hiroaki, Tabe Yuka

    Meeting abstracts of the Physical Society of Japan   68 ( 2 ) 314 - 314  2013.08

    CiNii

  • 1c12 Microscopic dynamics of smectic liquid crystalline monolayers

    Watanabe Go, Tabe Yuka

      ( 2012 ) "1c12 - 1"-"1c12-2"  2012.08

     View Summary

    Smectic liquid crystalline monolayers have long been studied as the ideal two-dimensional system. In spite of that, the diffusion behavior of smectic monolayers, which is one of the important fundamental physical properties, has not been understood yet. For the purpose of analyzing this property, we carried out molecular dynamics simulations for the system of smectic monolayers. As a result, it was figured out that the diffusion parallel to the director is much faster than the one perpendicular to the director. It suggests that the inplane molecular diffusion in the smectic monolayer is not isotropic, but anisotropic.

    CiNii

  • 1c11 DC field-induced non-equilibrium dynamics of smectic bubbles (II)

    Sugisawa Shin-ya, Harada Yuki, Hanehara Sho, Tabe Yuka

      ( 2012 ) "1c11 - 1"-"1c11-2"  2012.08

     View Summary

    Under DC electric field, bubbles composed of smectic LCs sometimes exhibit the unique dynamics as well as the macro deformations. We observed a string-like pattern appearing on the bubble surface during a short period just after the DC electric field was applied. As 2D Rayleigh-Taylor instability, we examined and analyzed the observed string patterns, which may be used for a liquid jet technology.

    CiNii

  • Deformations of Smectic Bubbles under Chemical and Electric Forces

    TABE Yuka, SUGISAWA Shin-ya, ISHII Yoko

    液晶 : 日本液晶学会誌 = Ekisho   16 ( 1 ) 30 - 37  2012.01

    CiNii

  • Chiral LC Molecular Motor Driven by Transmembrane Water Transfer

    TABE Yuka

    Seibutsu Butsuri   50 ( 1 ) 30 - 31  2010.01

    DOI CiNii

  • Soft Matter Physics Group in Waseda University

    TABE Yuka

    液晶 : 日本液晶学会誌 = Ekisho   13 ( 2 ) 151 - 152  2009.04

    CiNii

  • 液晶単分子膜における自己組織化構造

    多辺 由佳

    自己組織化ハンドブック   第2編 ( 第一章 ) 574 - 577  2009

  • キラル液晶のナノマシン

    多辺 由佳

    最新分子マシン     80 - 84  2008.04

  • Chiral LC Molecular Motor

    TABE Yuka

    Journal of the Japanese Liquid Crystal Society   10 ( 3 ) 65 - 71  2006.07

    CiNii

  • 29pRH-3 Non-equilibrium Dynamics in Two-dimensional Liquid Crystals

    Tabe Yuka

    Meeting abstracts of the Physical Society of Japan   61 ( 1 ) 377 - 377  2006.03

    CiNii

  • 3C02 Structural transformation of topological defects in liquid-crystal emulsions by means of photochemical modulation of surface anchoring

    YAMAMOTO Takahiro, TABE Yuka, YOKOYAMA Hiroshi

      ( 2005 ) 209 - 210  2005.09

    CiNii

  • 1C08 Nonequilibrium dynamics of chiral liquid crystal films : Effects of hydrodynamic flows

    Okuzono Tohru, Tabe Yuka, Yokoyama Hiroshi

      ( 2005 ) 61 - 62  2005.09

    CiNii

  • Photo-induced Orientational Waves in Liquid-Crystalline Monolayers : Spatio-temporal Patterns in Nonequilibrium Soft Matter

    OKUZONO Tohru, TABE Yuka, YOKOYAMA Hiroshi

    Butsuri   60 ( 4 ) 289 - 293  2005.04

     View Summary

    When a liquid-crystalline monolayer composed of photoreactive molecules is illuminated with weak polarized light, traveling waves with respect to the molecular orientation (orientational waves) are observed. This spatio-temporal pattern formation is recognized as a typical nonequilibrium phenomenon observed in soft condensed matter. We construct a phenomenological continuum model which well reproduces qualitatively features of the phenomenon. This model says that the orientational waves are formed as a result of an interplay between the spontaneous splay deformation of orientation and the anisotropy of photo-excitation.

    CiNii

  • 27aZD-6 Nonequilibrium dynamics of chiral liquid-crystalline monolayers

    Okuzono Tohru, Tabe Yuka, Yokoyama Hiroshi

    Meeting abstracts of the Physical Society of Japan   60 ( 1 ) 373 - 373  2005.03

    CiNii

  • 液晶が作る分子機械

    多辺 由佳

    表面科学   26   95 - 101  2005

  • キラル液晶分子モーター

    多辺 由佳

    固体物理   39 ( 10 ) 679 - 685  2004.10

    CiNii

  • 1C10 Optical modulation of liquid-crystal suspensions by means of photoisomerization of azobenzene derivatives

    YAMAMOTO Takahiro, TABE Yuka, ARIMURA Takashi, YAMAGUCHI Tomohiko, YOKOYAMA Hiroshi

      ( 2004 ) 214 - 215  2004.09

     View Summary

    We investigated optical control of light-scattering properties in liquid-crystal suspensions by means of photoisomerization of azobenzene derivatives. Liquid-crystal suspensions, azobenzene-containing nematic liquid crystals dispersed with small polymer particles (φ〜3μm), scattered light strongly in nematic phase. This would be attributable to polydomain structures and large birefringence of liquid crystals. The light-scattering state turned into a transparent one when the polydomain structures were erased by means of trans-to-cis photoisomerization of the doped azobenzene dye in which the nematic-to-isotropic phase transition was induced. The transparent state could be switched to the initial light-scattering state by a recovery of the nematic phase where the cis-to-trans photoisomerization occurred.

    CiNii

  • 二次元強誘電ネマティック液晶 (特集 液晶化学の最前線)

    多辺 由佳

    化学工業   55 ( 6 ) 437 - 442  2004.06

    CiNii

  • 27aWF-7 Nonequilibrium dynamics of liquid-crystalline Langmuir monolayers

    Okuzono Tohru, Tabe Yuka, Yokoyama Hiroshi

    Meeting abstracts of the Physical Society of Japan   59 ( 1 ) 350 - 350  2004.03

    CiNii

  • Pattern Formation of Two-Dimensional Liquid Crystals

    Tabe Yuka

    Bulletin of the Japan Society for Industrial and Applied Mathematics   14 ( 2 ) 55 - 59  2004

    DOI CiNii

  • カイラル液晶単分子膜の非平衡ダイナミクス(ソフトマターの物理学2004-変形と流動-,研究会報告)

    奥薗 透, 多辺 由佳, 横山 浩

    物性研究   83 ( 3 ) 321 - 322  2004

     View Summary

    この論文は国立情報学研究所の電子図書館事業により電子化されました。

    CiNii

  • 2次元の液晶状態:ラングミュア膜液晶の不思議な世界 (新春特集 液晶材料の開発と展望)

    多辺 由佳, 横山 浩

    機能材料   24 ( 1 ) 59 - 70  2004.01

    CiNii

  • Ferroelectoric Nematic Monolayer

    TABE Yuka

    Journal of the Japanese Liquid Crystal Society   7 ( 4 ) 314 - 321  2003.10

    CiNii

  • Forum for Liquid Crystals in Lyotropic and Biological Systems

    TABE Yuka

      6 ( 1 ) 112 - 113  2002.01

    CiNii

  • P25 液晶ラングミュア膜の分子動力学シミュレーション(基研研究会「ソフトマターの物理学」,研究会報告)

    青木 圭子, 多辺 由佳, 山本 貴広, 米谷 慎, 横山 浩

    物性研究   79 ( 2 ) 266 - 266  2002

    CiNii

  • Forum for Liquid Crystals in Lyotropic and Biological Systems

    TABE Yuka

      4 ( 1 ) 105 - 106  2000.01

    CiNii

  • Orientational Fluctuations in 2D Liquid Crystalline Langmuir Monolayers

    TABE Yuka, FEDER Aryeh, MAZUR Eric, YOKOYAMA Hiroshi

    Meeting abstracts of the Physical Society of Japan   53 ( 2 ) 844 - 844  1998.09

    CiNii

  • Light-induced reorientation of nematic liquid crystals and the Freedericksz transition

    Yokoyama Hiroshi, Tabe Yuka

    Preprints of Symposium on Liquid Crystals   23   308 - 309  1997.09

     View Summary

    We formulated previously a phenomenological theory of light-induced reorientation of nematic liquid crystals driven by the trans〓cis photoisomerization of photochromic molecules dispersed in liquid crystal media. Extending this theory, we discuss here the influence of light-induced reorientation in the Freedericksz transition.

    CiNii

  • 28p-WF-1 Two-dimensional liquid crystals : phase transition, elasticity and pattern formation

    Yokoyama H, Tabe Y

    Meeting abstracts of the Physical Society of Japan   52 ( 1 ) 750 - 750  1997.03

    CiNii

  • Optics of Langmuir monolayers and direct visualization techniques

    TARE Yuka

    OYOBUTURI   66 ( 3 ) 247 - 251  1997

    DOI CiNii

  • Surface elasticity and the stability of higher order point defects

    Yokoyama H., Braun F. N., Tabe Y.

    Preprints of Symposium on Liquid Crystals   22   297 - 298  1996.09

     View Summary

    In the smectic C-like phase of an azobenzene derivative Langmuir monolayer, spontaneous formation of variety of modulated structures such as stripes and spirals takes place. Particularly notable finding is that orientational point defects with an extremely large strength are stable in contrast to the almost complete absence of higher order point defects in bulk liquid crystals. This paper discusses the origin of the stability in terms of an extended 2D Frank continuum theory taking account of the surface specific elastic term.

    CiNii

  • ラングミュア膜の液晶構造

    多辺 由佳, 横山 浩

    固体物理   30 ( 10 ) p891 - 896  1995.10

    CiNii

  • Spatiotemporal Pattern in Two-dimensional Liquid Crystalline Phase of Langmuir Monolayers of Amphiphilic Azobenzene Derivative

    Tabe Yuka, Yokoyama Hiroshi

    Preprints of Symposium on Liquid Crystals   21   114 - 115  1995.09

     View Summary

    The azobenzene monolayer spontaneously develops a stripe pattern resulting from the in-plane rotation of molecular long axes in the thermal equilibrium state. When the constituent photochromic molecules are excited to undergo trans-cis photoisomerizations, the liquid crystalline Langmuir monolayer exhibits an anomalous reorientational response, followed by a generation of 2D traveling orientational waves.

    CiNii

  • Phenomenological Theory of Light-Induced Reorientation

    Yokoyama Hiroshi, Tabe Yuka

    Preprints of Symposium on Liquid Crystals   21   2 - 3  1995.09

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    A phenomenological theory is developed for light-induced reorientation of liquid crystals driven by the trans&xharr;cis photoisomerization of photochromic molecules bound to the surface of or dispersed in liquid crystal media. The present theory successfully accounts for previous observations, which are to suggest the role played by the liquid-crytallinity of the host medium and is thus out of the range of usual explanations based on the photoselection mechanism.

    CiNii

  • アゾベンゼンラングミュア膜における新しい2次元液晶構造 (超分子の電子機能に関する研究<特集>)

    多辺 由佳, 横山 浩

    電子技術総合研究所彙報   59 ( 8 ) p539 - 545  1995.08

    CiNii

  • Spatio-temporal pattern formation in two-dimensional mesophases of Langmuir monolayers

    Tabe Yuka, Yokoyama Hiroshi

    Abstracts of the meeting of the Physical Society of Japan. Annual meeting   50 ( 3 ) 642 - 642  1995.03

    CiNii

  • ラングミュア膜における二次元液晶相

    多辺 由佳, 横山浩

    物理学会誌   50   477 - 480  1995

  • Higher-order Disclination in Two-dimensional Liquid Crystalline Phase in Langmuir Monolayers

    TABE Yuka, YOKOYAMA Hiroshi

    Preprints of Symposium on Liquid Crystals   20   302 - 303  1994.09

    CiNii

  • 2p-C-5 Spatio-temporal pattern formation in two-dimensional mesophases of Langmuir monolayers

    Tabe Yuka, Yokoyama Hiroshi

    Abstracts of the meeting of the Physical Society of Japan. Sectional meeting   1994 ( 3 ) 434 - 434  1994.08

    CiNii

  • Critical Point of Nematic-Isotropic Phase Transition in Bounded Thin Films

    Yokoyama Hiroshi, Tabe Yuka

    Preprints of Symposium on Liquid Crystals   19   236 - 237  1993.09

    CiNii

  • Nematic-Isotropic Transition in Bounded Thin Films

    Yokoyama Hiroshi, Tabe Yuka

    Preprints of Symposium on Liquid Crystals   18   410 - 411  1992.09

    CiNii

  • 28a-M-11 MAGNETIC PROPERTIES OF LB FILMS OF DOCOSYLPYRIDINIUM-(TCNQ)_2

    Ikegami K, Kuroda S, Tabe Y, Saito K, Sugi M, Nakamura T, Tachibana H, Matsumoto M, Kawabata Y

      47 ( 2 ) 342 - 342  1992.03

    CiNii

  • 28a-ZF-5 Electron Spin Resonance in LB Films of Isotope : Substituted Merocyanine Dyes(II)

    Kuroda S., Ikegami K., Tabe Y., Saito K., Sugi M.

      46 ( 2 ) 313 - 313  1991.09

    CiNii

  • 29p-ZF-13 ESR STUDY ON LANGMUIR-BLODGETT FILMS OF CHARGE-TRANSFER COMPLEXES (XV)

    Ikegami K., Kuroda S., Tabe Y., Saito K., Sugi M., Matsumoto M., Nakamura T., Tachibana H., Kawabata Y.

      46 ( 2 ) 335 - 335  1991.09

    CiNii

  • 25a-Z-4 Electron Spin Resonance in LB Films of Isotope-Substituted Merocyanine Dyes

    Kuroda S., Ikegami K., Tabe Y., Saito K., Saito M., Sugi M.

      1991 ( 2 ) 333 - 333  1991.03

    CiNii

  • 25a-Z-5 ESR STUDY ON LANGMUIR-BLODGETT FILMS OF CHARGE-TRANSFER COMPLEXES(XIV)

    Ikegami K., Kuroda S., Tabe Y., Saito K., Saito M., Sugi M., Nakamura T., Tachibana H., Matsumoto M., Kawabata Y.

      1991 ( 2 ) 333 - 333  1991.03

    CiNii

  • 5a-K-12 ESR STUDY ON LANGMUIR-BLODGETT FILMS OF CHARGE-TRANSFER COMPLEXES(XII)

    IKEGAMI.K, KURODA.S, TABE.Y, SAITO.K, SAITO.M, SUGI.M, NAKAMURA.T, TACHIBANA.H, MATSUMOTO.M, KAWABAT.Y

      1990 ( 2 ) 364 - 364  1990.09

    CiNii

  • 5a-K-13 ESR STUDY ON LANGMUIR-BLODGETT FILMS OF CHARGE-TRANSFER COMPLEXES (XIII)

    IKEGAMI.K, KURODA.S, TABE.Y, SAITO.K, SAITO.M, SUGI.M, TACHIBANA.H, NAKAMURA.T, MATSUMOTO.M, KAWABATA.Y

      1990 ( 2 ) 365 - 365  1990.09

    CiNii

  • 5a-K-11 Electron Spin Resonance in Langmuir-Blodgett Films of Merocyanine Dyes(X VI)

    KURODA.S, IKEGAMI.K, TABE.Y, SAITO.K, SAITO.M, SUGI.M

      1990 ( 2 ) 364 - 364  1990.09

    CiNii

  • ESR STUDY ON LANGMUIR-BLODGETT FILMS OF CHARGE-TRANSFER COMPLEXES (XI)

    IKEGAMI K., KURODA S., TABE Y., SAITO K., SAITO M., SUGI M., NAKAMURA T., TACHIBANA H., MATSUMOTO M., KAWABATA Y.

      45 ( 2 ) 321 - 321  1990.03

    CiNii

  • Electron Spin Resonance in Langmuir-Blodgett Films of Merocyanine Dyes (XV)

    Tabe Y., Ikegami K., Kuroda S., Saito K., Saito M., Sugi M.

      45 ( 2 ) 320 - 320  1990.03

    CiNii

  • 6a-L-9 Electron Spin Resonance in Langmuir-Blodgett Films of Merocyanine Dyes (XIII)

    KURODA S., TABE Y., IKEGAMI K., SAITO K., SAITO M., SUGI M.

      1989 ( 2 ) 323 - 323  1989.09

    CiNii

  • 29p-P-11 Mechanical Properties of Lipid Bilayers at Low Frequencies

    Tabe Y., Yamamoto J., Okano K.

      44 ( 2 ) 301 - 301  1989.03

    CiNii

  • E-1 Mechanical Properties of Lipid Bilayers at Low Frequencies

    Tabe Yuka, Yamamoto Jun, Okano Koji

    Symposium on ultrasonic electronics   ( 9 ) 145 - 146  1988.12

    CiNii

  • Mechanical Properties of Lipid Bilayers at Low Frequencies

    Tabe Y., Yamamoto J., Okano K.

    Preprints of Symposium on Liquid Crystals   14   180 - 181  1988.09

    CiNii

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  • 光で走る・水で回る液晶-女性研究者はおだて上手?-

    千葉市科学館  大人のための科学教室 

    2014.09
     
     

Overseas Activities

  • キラル結晶の動的交差相関を利用した液晶モーターの研究

    2011.04
    -
    2011.09

    アメリカ   ケント州立大学液晶研究所

Sub-affiliation

  • Faculty of Science and Engineering   Graduate School of Advanced Science and Engineering

Research Institute

  • 2023
    -
    2027

    Kagami Memorial Research Institute for Materials Science and Technology   Flexible Researcher

  • 2022
    -
    2024

    Waseda Research Institute for Science and Engineering   Concurrent Researcher

Internal Special Research Projects

  • 液晶界面の異常低摩擦の解明

    2020  

     View Summary

    ネマチック液晶を等方相との共存温度下におくと,液体相中に液晶滴が分散する。この液晶滴にトルクを印加して定常回転させたとき,外力と粘性抵抗のつり合いで角速度が決まる。我々は,この実験で見積もられる粘性率が,一般実験で測定した液体相の粘性係数に比べ,桁違いに小さいことを見出した。トレーサー粒子追跡法で回転滴周囲の速度場を調べたところ,滴表面から数ミクロン離れる位置では回転流が観測されなかった。この結果は,液晶相と液体相が接する界面では一般的なnon-slip条件が成立しないことを示唆する。液体―液晶共存界面の動的性質はこれまで調べられておらず,ソフト界面の特異性が注目される。

  • 電子線で回転するソフトクリスタル:構造とメカニズム

    2019  

     View Summary

    鏡面対称性が破れた構造を持つソフトマターは、線形流によって分子の受けたトルクを集団運動に変換し、一方向に回転することが可能である。近年、これを用いたソフトマシーンを作ろうという試みが行われており、特に、トルクを生み出すエネルギー源として、温度勾配(熱流)が注目されている。我々が見出した、電子線で一方向回転するソフトクリスタルにおいても、電子線によって試料内に生じた温度勾配が回転を駆動する可能性が指摘されていることから、本研究では、同じ対称性を持つコレステリック液晶滴に温度勾配を印加し、回転を調べた。温度勾配下のコレステリック滴は顕微鏡下でテクスチュアの一方向回転を示すが、これが配向回転によるものか剛体回転によるものかは区別できない。そこで試料にマイクロ粒子を分散させ、滴表面に吸着した粒子が滴中心のまわりを公転することを観測し、剛体回転の証拠を得た。さらに、滴中心に対して公転する粒子をピン止めすると、逆に滴が粒子を中心に公転すること、また2つの滴を粒子でつなぐと粒子を中心に2つの滴が公転すること、を示すことができた。

  • 異常な動的構造を示す電荷移動液晶

    2019  

     View Summary

    電子吸引性の液晶化合物と中性の液晶化合物を同比率で混合すると、混合液晶がSmE相やSmB相などの高秩序液晶相を示すことがある。本研究で我々は、電子吸引性の液晶化合物に1割以下の割合で中性分子を混合したとき、混合液晶の静的構造は変わらないにもかかわらず、動的物性が大きく変化することを見出した。中性分子の割合が小さいとき、混合液晶は母物質と同じく二次元液体的なSmA相を示す。静的構造は同じだが、混合液晶を1ミクロン程度の厚さの薄膜にして酸素を透過させると、中性分子のモル比が0.05を超えたところで、酸素透過率が急に1桁低下した。さらにこの薄膜を破壊すると、破壊の進む速さが同じ閾値で、不連続に2桁低下した。可能性として、混合液晶のSmA相には高秩序相のナノドメインが高速で生消滅しており、静的には同じ相であっても、固いナノドメインが分子の動きを阻害し、粘性を大きく増大させていることが考えられる。マイクロ秒以下で生消滅する100nm以下の小さなクラスターの存在を、マクロな実験で明らかにした。

  • キラル液晶の回転による熱輸送―分子からマクロへの階層的運動変換ー

    2018  

     View Summary

    等方相と共存するキラルな液晶滴を温度勾配下に置くと、熱流により液晶滴の一方向回転が駆動される。これをマイクロモーターに応用することを目指し、ダブルツイストシリンダー(DTC)構造を持つ液晶滴の剛体回転を試みた。DTC内の分子は、円柱軸上では軸方向に、中心から円柱側面に向かっては一方向に捩じれたプロペラと類似の構造を持つ。我々は、先行研究にはない数ミクロンという大きな半径を持つ巨大なDTCを作製し、それを集合体にすることに成功した。得られたDTCの円柱軸方向に熱流を流すと、DTC集合体は形状を崩すことなく、これまでより1桁以上高速で剛体回転することが明らかになった。

  • キラル液晶の回転による熱・物質輸送

    2017  

     View Summary

    液晶の新機能として、「キラル液晶の回転による一方向の熱輸送」が理論予測されている。実現できれば、液晶を一方向に回転させると回転軸に沿って熱が輸送される、という他に無いデバイスが得られる。ただし、キラル液晶の回転と熱との結合は一般に弱いため、実証には精密な測定系が必要となる。本研究では、実験で得られている熱→回転への変換係数から回転によって生じるべき熱流を見積もり、その微小な熱流の測定を可能とするシステムの構築を行った。10mmx10mmの熱電堆を2つのコレステリック液晶セルではさみ、全体を二重の断熱系に入れた系を作製した結果、平衡時の熱揺らぎを±0.05microW/mm2まで軽減することができた。&nbsp;

  • 熱・物質流で誘起されるキラル・アキラル液晶薄膜の動的構造:その仕組みと制御

    2015  

     View Summary

    キラル液晶に物質や熱流を透過させると、膜を構成する分子が位相をそろえて集団回転する。我々は、この回転能を持つキラル液晶ドメインを気液界面に張られた脂質単分子膜に埋め込み、疑似生体膜を作製することを試みた。まず液晶ドメインが分散した膜を作ることに成功し、続いて膜にアルコール蒸気を透過させたところ、液晶ドメインの配向を一方向回転させることができた。特徴的なのは、気相から液相へエタノール蒸気が移動した時にのみ、液晶分子が一方向回転を示したことである。弁がついているかのような挙動は生体ではよく見られるものなので、今後、液晶ドメインが弁機能を持つ仕組みを調べ、生体の一方向運動を理解するモデル系にしたいと考えている。

  • 液晶性ラングミュア膜の配向揺らぎで見る界面近傍の液晶分子配向挙動

    2014  

     View Summary

    界面・表面での分子配向は、様々な分野で基礎・応用両面から重要な研究課題である。本研究では、液晶パネルの性能に大きな影響を及ぼす基板界面での液晶分子の構造と挙動を、光散乱実験と新規解析法により調べた。界面局所構造を取り出すため、バルクの液晶ではなく液晶性ラングミュア膜を対象とし、単分子層液晶の配向揺らぎが下相水の性質にどのように依存するかを調べた。下相をアガロース低濃度水溶液とし、濃度を変えながら上にある液晶単分子膜の配向揺らぎを測定した結果、10-3 wt%という極低濃度溶液でも、配向揺らぎが完全に止まることがわかった。液晶構造には変化はなく、ダイナミクスのみにソフト界面は影響を与える。

  • キラル液晶分子モーターを埋め込んだ機能性擬似生体膜の実現

    2005  

     View Summary

    気液界面に作られたキラルな液晶単分子膜では、構成分子が物質流によって一方向に集団運動をすることを応用し、モーター機能を持った擬似生体膜の製作に取り組んだ。まず、生体膜のおかれた環境である、イオンを含む水溶液中にキラル液晶薄膜を作ることを試みた。手法として我々は独自に凍結―融解方法を考案、それを用いて液晶状態の薄膜を水溶液中に作ることに成功した。できた膜の構造を見るために高精度な偏光顕微鏡を組み立て、その観察にも成功した。できた薄膜は厚さが数百ナノメートル、初期状態ではほぼ一様な配向を示す。次に、生体膜中のモーター蛋白と同じく、膜を透過するプロトンによって液晶分子を回転させることを試みた。この目的のため、膜だけを接触面とする2つの区切られたセルを設計・作製し、一方のセルに純水、もう一方のセルに酸性水を入れて、プロトン濃度勾配を膜に与えた。単純な拡散だけではプロトンの単位時間当たり透過量が十分ではなかったため、さらに電解をかけて移動を加速したところ、一定電場を超えた時点でキラル分子が集団回転する様子が観測された。回転の速度はかける電場の強さに比例し、分子回転がプロトン流に駆動されて生じていることが確かめられた。液晶薄膜の液体中での製作は初めての成功例であり、そのこと自体も意味のあることである。さらに、キラル液晶分子が薄膜状態で、モーター蛋白と同様プロトン駆動で回転することを確認できたことも大きな意味がある。この結果をふまえて、液晶薄膜のナノサイズ化、リン脂質との混合など、ドラッグデリバリーなどにも使える擬似生体膜の製作を今後目指していくと同時に、分子スケールの運動とマクロな回転とを結ぶメソスコピック領域での運動変換について、メカニズムを明らかにしたい。

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