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Vorotnikov AP. An EPR study of the orientational transition in smectic liquid crystals in a magnetic field. RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY B 2016. [DOI: 10.1134/s1990793115050139] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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2
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Beguin L, Emsley JW, Lelli M, Lesage A, Luckhurst GR, Timimi BA, Zimmermann H. The Chirality of a Twist–Bend Nematic Phase Identified by NMR Spectroscopy. J Phys Chem B 2012; 116:7940-51. [PMID: 22681586 DOI: 10.1021/jp302705n] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Laetitia Beguin
- Université de Lyon, CNRS/ENS Lyon/UCB-Lyon 1, Centre RMN à
Très Hauts Champs, 5 rue de la Doua, 69100 Villeurbanne, France
| | - James W. Emsley
- School of Chemistry, University of Southampton, Highfield, Southampton SO17
1BJ, United Kingdom
| | - Moreno Lelli
- Université de Lyon, CNRS/ENS Lyon/UCB-Lyon 1, Centre RMN à
Très Hauts Champs, 5 rue de la Doua, 69100 Villeurbanne, France
| | - Anne Lesage
- Université de Lyon, CNRS/ENS Lyon/UCB-Lyon 1, Centre RMN à
Très Hauts Champs, 5 rue de la Doua, 69100 Villeurbanne, France
| | - Geoffrey R. Luckhurst
- School of Chemistry, University of Southampton, Highfield, Southampton SO17
1BJ, United Kingdom
| | - Bakir A. Timimi
- School of Chemistry, University of Southampton, Highfield, Southampton SO17
1BJ, United Kingdom
| | - Herbert Zimmermann
- Department
of Biophysics, Max-Planck-Institut für Medizinische Förschung, D-69120 Heidelberg, Germany
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Hamasuna D, Luckhurst GR, Sugimura A, Timimi BA, Zimmermann H. Director alignment by crossed electric and magnetic fields: a deuterium NMR study. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 84:011705. [PMID: 21867194 DOI: 10.1103/physreve.84.011705] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2011] [Indexed: 05/31/2023]
Abstract
The static director distribution in thin nematic liquid crystal cells, subject to both electric and magnetic fields, has been investigated using a combination of deuterium nuclear magnetic resonance (NMR) spectroscopy and continuum theory in terms of the director distribution function, which gives the probability density for finding the director at a given orientation. A series of deuterium NMR spectra for the nematic liquid crystal, 4-pentyl-d(2)-4'-cyanobiphenyl deuteriated in the α position of the pentyl chain were acquired as a function of the applied electric field. This powerful experimental technique allowed us to observe uniform and nonuniform director alignment depending on the angle between the two fields and their relative strength. On the basis of the detailed experimental results, we have explored the factors that influence the nature of both the uniform and the nonuniform director distributions. We have discussed the questions that are raised by our attempt to understand the static director distribution as a function of the angle between the two fields. We have discovered that the alignment of the director at the surface of the Teflon spacers is essential in addition to the random variation in the cell thickness in order to account for the static director distribution determined from the NMR spectra.
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Affiliation(s)
- D Hamasuna
- Department of Information Systems Engineering, Osaka Sangyo University, 3-1-1 Nakagaito, Daito-Shi, Osaka 574-8530, Japan
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McKenzie I, Dilger H, Stoykov A, Scheuermann R. Muon Spin Spectroscopy of the Nematic Liquid Crystal 4-n-Pentyl-4′-cyanobiphenyl (5CB). J Phys Chem B 2009; 113:10135-42. [DOI: 10.1021/jp9025656] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Iain McKenzie
- ISIS Pulsed Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, U.K. OX11 0QX, Institut für Physikalische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany, and Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen, Switzerland
| | - Herbert Dilger
- ISIS Pulsed Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, U.K. OX11 0QX, Institut für Physikalische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany, and Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen, Switzerland
| | - Alexey Stoykov
- ISIS Pulsed Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, U.K. OX11 0QX, Institut für Physikalische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany, and Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen, Switzerland
| | - Robert Scheuermann
- ISIS Pulsed Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, U.K. OX11 0QX, Institut für Physikalische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany, and Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen, Switzerland
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5
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Brimicombe PD, Siemianowski SD, Jaradat S, Levine YK, Thompson P, Bras W, Gleeson HF. Time-resolved x-ray studies of the dynamics of smectic- A layer realignment by magnetic fields. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2009; 79:031706. [PMID: 19391961 DOI: 10.1103/physreve.79.031706] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2008] [Revised: 02/09/2009] [Indexed: 05/27/2023]
Abstract
While the rotation of smectic layers under an applied field may at first appear to be a relatively simple problem, the dynamic processes involved are rather complex. An applied field produces a torque on the liquid crystal director, but has no direct influence on the smectic layers. If the director is reoriented significantly, however, the layers must also reorient in order to accommodate this (the layered structure is produced by short-range molecular interactions). Indeed, if the liquid crystalline order is not maintained during the realignment then matters become even more complex. In this paper we use time-resolved x-ray scattering to investigate the realignment of smectic- A layers in thin-film devices using a magnetic field. No evidence is found for continuous rotation of the smectic layers under any circumstances in such devices, a result that is not found when using bulk samples. No evidence indicating the formation of the nematic phase is observed during realignment. A molecular-dynamics technique is used to model the system which indicates that the sample becomes significantly disorganized during the realignment process when large angular rotations are induced.
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Affiliation(s)
- P D Brimicombe
- School of Physics and Astronomy, University of Manchester, Manchester, M13 9PL, United Kingdom
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Lefort R, Morineau D, Guégan R, Ecolivet C, Guendouz M, Zanotti JM, Frick B. Incoherent quasielastic neutron scattering study of molecular dynamics of 4-n-octyl-4′-cyanobiphenyl. Phys Chem Chem Phys 2008; 10:2993-9. [DOI: 10.1039/b718003a] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Galyametdinov YG, Haase W, Goderis B, Moors D, Driesen K, Van Deun R, Binnemans K. Magnetic Alignment Study of Rare-Earth-Containing Liquid Crystals. J Phys Chem B 2007; 111:13881-5. [DOI: 10.1021/jp0771724] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yury G. Galyametdinov
- Physical and Colloid Chemistry Department, Kazan State Technological University, Karl Marx Street 68, 420015 Kazan, Russia, Kazan Physical-Technical Institute, Russian Academy of Sciences, Sibirsky Tract 10/7, 420029 Kazan, Russia, Institute of Physical Chemistry, Darmstadt University of Technology, Petersenstrasse 20, D-64287 Darmstadt, Germany, and Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200F − bus 2404, B-3001 Leuven, Belgium
| | - Wolfgang Haase
- Physical and Colloid Chemistry Department, Kazan State Technological University, Karl Marx Street 68, 420015 Kazan, Russia, Kazan Physical-Technical Institute, Russian Academy of Sciences, Sibirsky Tract 10/7, 420029 Kazan, Russia, Institute of Physical Chemistry, Darmstadt University of Technology, Petersenstrasse 20, D-64287 Darmstadt, Germany, and Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200F − bus 2404, B-3001 Leuven, Belgium
| | - Bart Goderis
- Physical and Colloid Chemistry Department, Kazan State Technological University, Karl Marx Street 68, 420015 Kazan, Russia, Kazan Physical-Technical Institute, Russian Academy of Sciences, Sibirsky Tract 10/7, 420029 Kazan, Russia, Institute of Physical Chemistry, Darmstadt University of Technology, Petersenstrasse 20, D-64287 Darmstadt, Germany, and Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200F − bus 2404, B-3001 Leuven, Belgium
| | - Dries Moors
- Physical and Colloid Chemistry Department, Kazan State Technological University, Karl Marx Street 68, 420015 Kazan, Russia, Kazan Physical-Technical Institute, Russian Academy of Sciences, Sibirsky Tract 10/7, 420029 Kazan, Russia, Institute of Physical Chemistry, Darmstadt University of Technology, Petersenstrasse 20, D-64287 Darmstadt, Germany, and Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200F − bus 2404, B-3001 Leuven, Belgium
| | - Kris Driesen
- Physical and Colloid Chemistry Department, Kazan State Technological University, Karl Marx Street 68, 420015 Kazan, Russia, Kazan Physical-Technical Institute, Russian Academy of Sciences, Sibirsky Tract 10/7, 420029 Kazan, Russia, Institute of Physical Chemistry, Darmstadt University of Technology, Petersenstrasse 20, D-64287 Darmstadt, Germany, and Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200F − bus 2404, B-3001 Leuven, Belgium
| | - Rik Van Deun
- Physical and Colloid Chemistry Department, Kazan State Technological University, Karl Marx Street 68, 420015 Kazan, Russia, Kazan Physical-Technical Institute, Russian Academy of Sciences, Sibirsky Tract 10/7, 420029 Kazan, Russia, Institute of Physical Chemistry, Darmstadt University of Technology, Petersenstrasse 20, D-64287 Darmstadt, Germany, and Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200F − bus 2404, B-3001 Leuven, Belgium
| | - Koen Binnemans
- Physical and Colloid Chemistry Department, Kazan State Technological University, Karl Marx Street 68, 420015 Kazan, Russia, Kazan Physical-Technical Institute, Russian Academy of Sciences, Sibirsky Tract 10/7, 420029 Kazan, Russia, Institute of Physical Chemistry, Darmstadt University of Technology, Petersenstrasse 20, D-64287 Darmstadt, Germany, and Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200F − bus 2404, B-3001 Leuven, Belgium
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Levine YK, Polimeno A. A dissipative particle dynamics study of the realignment of a nanodroplet of a nematic in a weak external magnetic field. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2007; 23:13-23. [PMID: 17497077 PMCID: PMC2798057 DOI: 10.1140/epje/i2006-10080-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/16/2006] [Accepted: 04/20/2007] [Indexed: 05/15/2023]
Abstract
We present a dissipative particle dynamics (DPD) approach for simulating the realignment of a nematic nanodroplet suspended in an isotropic fluid following a switch in the direction of an applied external magnetic field. The interaction of the mesogens with the external field is weak relative to the inter-molecular interactions. The simulations were used to investigate the way orientational equilibrium is re-established. The results reveal that the realignment process of the nanodroplet is consistent with its fluid structure. The reorientation of the nanodroplet as a whole is found to be caused by an internal structural rearrangement rather than a coherent rotation of the centres of mass of the mesogens about the centre of the nanodroplet. The switch in the field direction furthermore is found to induce a transient spatial variation in the orientational order of the long axes of the mesogens: the orientational order parameters decreases on moving from the core of the nanodroplet to the surface in contact with the isotropic environment. The results highlight differences between the time evolution of the orientation of the long molecular axes in the field and the rotations of the centres of mass of the mesogens about the centre of the nanodroplet.
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Affiliation(s)
- Y. K. Levine
- Section for Computational Biophysics, Department of Physics and Astronomy, Ornstein Laboratory, P.O. Box 80.000, 3508 TA Utrecht, The Netherlands
| | - A. Polimeno
- Dipartimento di Scienze Chimiche, Università di Padova, Via Loredan 2, 35131 Padova, Italy
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Luckhurst GR, Miyamoto T, Sugimura A, Timimi BA. Electric Field-Induced Alignment of the Directors in the Smectic A Phase of 4-Octyl-4′-Cyanobiphenyl. A Deuterium NMR Study. ACTA ACUST UNITED AC 2006. [DOI: 10.1080/10587250008024836] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Geoffrey R. Luckhurst
- a Department of Chemistry and Southampton Liquid , Crystal Institute, University of Southampton , Southampton , SO17 1BJ , UK
| | - Tetsuo Miyamoto
- b Department of Electronics and Physics , Osaka Prefecture University , Guken-cho, Sakai, Osaka , 599-8531 , Japan
| | - Akihiko Sugimura
- c Department of Information Systems Engineering , Osaka Sangyo University , 3-1-1 Nakagaito, Daito-Shi, Osaka , 574-8530 , Japan
| | - Bakir A. Timimi
- a Department of Chemistry and Southampton Liquid , Crystal Institute, University of Southampton , Southampton , SO17 1BJ , UK
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Luckhurst GR. Field-Induced Alignment of the Directors in the Smectic A Phase. Experiment and Simulation. ACTA ACUST UNITED AC 2006. [DOI: 10.1080/10587250008024834] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Geoffrey Roger Luckhurst
- a Department of Chemistry and Southampton Liquid , Crystal Institute, University of Southampton , Southampton , SO17 1BJ , UK
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Satoh K. Molecular dynamics simulation of the nematic liquid crystal phase in the presence of an intense magnetic field. J Chem Phys 2006; 124:144901. [PMID: 16626239 DOI: 10.1063/1.2186320] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The influence of an intense external field on the dynamics of the nematic liquid crystal phase is investigated using a molecular dynamics simulation for the Gay-Berne nematogen under isobaric-isothermal conditions. The molecular dynamics as a function of the second-rank orientational order parameter P<2> for a system consisting of a nematic liquid crystal in the presence of an intense magnetic field is compared with that of a similar system without the field. The translational motion of molecules is determined as a function of the translational diffusion coefficient tensor and the anisotropy and compared with the values predicted theoretically. The rotational dynamics of molecules is analyzed using the first- and the second-rank orientational time correlation functions. The translational diffusion coefficient parallel with respect to the director is constrained by the intense field, although the perpendicular one is decreased as the P<2> is increased, just as it is in the system without the field. However, no essential effect of the strong magnetic field is observed in the rotational molecular dynamics. Further, the rotational diffusion coefficient parallel with respect to the director obtained from the first-rank orientational time correlation function in the simulation is qualitatively in agreement with that in the real nematic liquid crystalline molecules. The P<2> dependence of the rotational diffusion coefficient for the system with the intense magnetic field shows a tendency similar to that for the system without the field.
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Affiliation(s)
- Katsuhiko Satoh
- College of General Education, Osaka Sangyo University, 3-1-1 Nakagaito, Daito, Osaka 574-8530, Japan.
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13
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Bras W, Emsley JW, Levine YK, Luckhurst GR, Seddon JM, Timimi BA. Field-induced alignment of a smectic-Aphase: A time-resolved x-ray diffraction investigation. J Chem Phys 2004; 121:4397-413. [PMID: 15332991 DOI: 10.1063/1.1776116] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The field-induced alignment of a smectic-A phase is, in principle, a complicated process involving the director rotation via the interaction with the field and the layer rotation via the molecular interactions. Time-resolved nuclear magnetic resonance spectroscopy has revealed this complexity in the case of the director alignment, but provides no direct information on the motion of the layers. Here we describe a time-resolved x-ray diffraction experiment using synchrotron radiation to solve the challenging problem of capturing the diffraction pattern on a time scale which is fast in comparison with that for the alignment of the smectic layers. We have investigated the alignment of the smectic-A phase of 4-octyl-4(')-cyanobiphenyl by a magnetic field. The experiment consists of creating a monodomain sample of the smectic-A phase by slow cooling from the nematic phase in a magnetic field with a flux density of 7 T. The sample is then turned quickly through an angle phi(0) about an axis parallel to the x-ray beam direction but orthogonal to the field. A sequence of two-dimensional small angle x-ray diffraction patterns are then collected at short time intervals. Experiments were carried out for different values of phi(0), and at different temperatures. The results show that the alignment behavior changes fundamentally when phi(0) exceeds 45 degrees, and that there is a sharp change in the alignment process when the temperature is less than 3 degrees C below the smectic-A-nematic transition. The results of the x-ray experiments are in broad agreement with the NMR results, but reveal major phenomena concerning the maintenance of the integrity of the smectic-A layer structure during the alignment process.
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Affiliation(s)
- W Bras
- Netherlands Organisation for Scientific Research (NWO), DUBBLE CRG, European Synchrotron Radiation Facility, Boite Postale 220, F-38043 Grenoble Cedex, France
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Acosta RH, Pusiol DJ. Reorientation dynamics in a nematic liquid crystal studied by fast field cycling nuclear magnetic resonance. J Chem Phys 2003. [DOI: 10.1063/1.1590308] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Dvinskikh SV, Furó I, Zimmermann H, Maliniak A. Anisotropic self-diffusion in thermotropic liquid crystals studied by 1H and 2H pulse-field-gradient spin-echo NMR. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2002; 65:061701. [PMID: 12188745 DOI: 10.1103/physreve.65.061701] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2002] [Indexed: 05/23/2023]
Abstract
The molecular self-diffusion coefficients in nematic and smectic-A thermotropic liquid crystals are measured using stimulated-echo-type 2H and 1H pulse-field-gradient spin-echo nuclear magnetic resonance (PGSE NMR) combined with multiple-pulse dipolar decoupling and slice selection. The temperature dependence of the principal components of the diffusion tensor in the nematic phase follows a simple Arrhenius relationship except in the region of nematic-isotropic phase transition where it reflects, merely, the decrease of the molecular orientational order. The average of the principal diffusion coefficients in the isotropic-nematic phase transition region is close to the diffusion coefficient in the isotropic phase. At the nematic-smectic-A phase transition the diffusion coefficients change continuously. The results in nematic phase are best described in terms of the affine transformation model for diffusion in nematics formed by hard ellipsoids. In the smectic-A phase the data are interpreted using a modified model for diffusion in presence of a periodic potential along the director.
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Affiliation(s)
- S V Dvinskikh
- Division of Physical Chemistry, Arrhenius Laboratory, Stockholm University, SE-10691 Stockholm, Sweden.
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Kitzerow HS. News about Soft Condensed Matter—A Liquid Crystal Meeting Review. Chemphyschem 2001; 2:628-32. [DOI: 10.1002/1439-7641(20011015)2:10<628::aid-cphc628>3.0.co;2-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Emsley J, Luckhurst G, Pedrielli P. Magnetic field induced alignment of the director in a smectic A phase: surface effects. Chem Phys Lett 2000. [DOI: 10.1016/s0009-2614(00)00236-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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