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Abstract
The problem of predicting structural and dynamic behavior associated with thin smectic films, both deposited on a solid surface or stretched over an opening, when the temperature is slowly increased above the bulk transition temperature towards either the nematic or isotropic phases, remains an interesting one in the physics of condensed matter. A useful route in studies of structural and optical properties of thin smectic films is provided by a combination of statistical–mechanical theories, hydrodynamics of liquid crystal phases, and optical and calorimetric techniques. We believe that this review shows some useful routes not only for the further examining of the validity of a theoretical description of thin smectic films, both deposited on a solid surface or stretched over an opening, but also for analyzing their structural, optical, and dynamic properties.
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Sliwa I, Zakharov AV. Structural and optical properties of free-standing smectic films. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2019; 42:78. [PMID: 31222584 DOI: 10.1140/epje/i2019-11842-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Accepted: 05/22/2019] [Indexed: 06/09/2023]
Abstract
We have carried out a complex numerical study of the structural, thermodynamic and optical properties of the partially fluorinated 5-n -alkyl-2-(4-n-(perfluoroalkyl-metheleneoxy)phenyl) free-standing smectic film in air under the action of the external electric field [Formula: see text]. Calculations, based upon the extended McMillan's mean-field theory with anisotropic forces, show a stepwise reduction of the value of the Helmholtz free energy and the reflectivity of the partially fluorinated smectic film in air, as the temperature is raised above the bulk smectic-A-isotropic transition value. It has been shown, by solving the self-consistent nonlinear equations for the orientational and translational order parameters, that the electric field [Formula: see text] may not only affect the layer-thinning transition sequences, but also change the first multilayer jump in the film thickness, whereas practically does not affect the reflectivity R(N) of the partially fluorinated N -layer smectic film in air. In the range of film thicknesses investigated, the reduction of the R(N) is, at least, qualitatively in agreement with the experimentally observed decrease of the optical reflectivity with the decrease of N.
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Affiliation(s)
- Izabela Sliwa
- Poznan University of Economics and Business, Department of Mathematical Economics, Al. Niepodleglosci 10, 61-875, Poznan, Poland
| | - A V Zakharov
- Saint Petersburg Institute for Machine Sciences, The Russian Academy of Sciences, 199178, Saint Petersburg, Russia.
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Zakharov AV, Sliwa I. Squeezing-out dynamics in free-standing smectic films. J Chem Phys 2015; 142:214703. [PMID: 26049512 DOI: 10.1063/1.4921960] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We have carried out a theoretical study of the dynamics of the removal of one smectic layer from the N-layer free-standing smectic film during the layer-thinning process. Squeezing-out is initiated by a thermally activated nucleation process in which a density fluctuation forms a small hole. The dynamics of the bounding area during the layer-thinning transition N → N - 1, when the nucleation occurs in the center of the circular smectic film and the squeezed-out area increases up to the edge of the circular smectic area, is studied by the use of the conservation laws for mass and linear momentum. The disjoining pressure is the main factor that is responsible for the driving out of one smectic layer from the N-layer smectic film.
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Affiliation(s)
- A V Zakharov
- Saint Petersburg Institute for Machine Sciences, The Russian Academy of Sciences, Saint Petersburg 199178, Russia
| | - Izabela Sliwa
- Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17, 60-179 Poznaǹ, Poland
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`Sliwa I, Zakharov A. Surface tension, disjoining pressure and layer compression of free-standing smectic films in water. Chem Phys Lett 2015. [DOI: 10.1016/j.cplett.2014.12.032] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Zakharov AV, Śliwa I. Surface tension and disjoining pressure of free-standing smectic films above the bulk smectic-A-isotropic transition temperature. J Chem Phys 2014; 140:124705. [PMID: 24697468 DOI: 10.1063/1.4869197] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We have carried out a numerical study of both the structural and thermodynamic properties of free-standing smectic films for the case of enhanced pair interaction in the bounding layers. Calculations, based upon the extended McMillan's mean-field theory with anisotropic forces, show that the layer-thinning transitions are characterized by abrupt drops to lower values, both for a disjoining pressure and a fluctuation-induced long-range interaction between the smectic film surfaces, and then continues to increase with a larger positive slope. Reasonable agreement between the theoretically predicted and the experimentally obtained data on the surface tension of the partially fluorinated 5-n-alkyl-2-(4-n-(perfluoroalkyl-metheleneoxy)phenyl) film has been obtained.
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Affiliation(s)
- A V Zakharov
- Saint Petersburg Institute for Machine Sciences, The Russian Academy of Sciences, Saint Petersburg 199178, Russia
| | - Izabela Śliwa
- Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17, 60-179 Poznaǹ, Poland
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Zakharov AV, Vakunenko AA. Influence of an external field on the surface tension of free-standing smectic films. Phys Rev E 2012; 86:031701. [PMID: 23030927 DOI: 10.1103/physreve.86.031701] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2012] [Revised: 08/01/2012] [Indexed: 11/07/2022]
Abstract
We have carried out a theoretical study of the effect of the electric field E on the thermodynamical properties and surface tension γ of free-standing smectic films. Calculations, based upon the extended McMillan approach with anisotropic forces, show a stepwise reduction and increase of the values of the Helmholtz free energy f and γ, respectively, per partially fluorinated 5-n-alkyl-2-[4-n-(perfluoroalkyl-metheleneoxy)phenyl] (H10F5MOPP) molecule, as the temperature is raised above that for the bulk smectic-A-isotropic transition. Calculations show that E may not only affect the layer-thinning transition sequence, but also change the first multilayer jump in the thickness and increase the value of γ per H10F5MOPP molecule. Reasonable agreement between the theoretically predicted and the experimentally obtained data on γ of the partially fluorinated H10F5MOPP film has been obtained.
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Affiliation(s)
- A V Zakharov
- Saint Petersburg Institute for Machine Sciences, The Russian Academy of Sciences, Saint Petersburg 199178, Russia.
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Zakharov AV, Sullivan DE. Transition entropy, Helmholtz free energy, and heat capacity of free-standing smectic films above the bulk smectic-A-isotropic transition temperature: a mean-field treatment. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2010; 82:041704. [PMID: 21230292 DOI: 10.1103/physreve.82.041704] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2009] [Revised: 07/02/2010] [Indexed: 05/30/2023]
Abstract
We have carried out a numerical study of both the structural and thermodynamic properties of free-standing smectic films (FSSFs) for two cases of enhanced pair interactions in the bounding layers. Calculations, based upon the extended McMillan's approach with anisotropic forces, shows a stepwise reduction of the value of the heat capacity as the temperature is raised above the bulk smectic A-isotropic transition. The effects of surface "enhanced" pair interactions in the bounding layers and of film thickness on the orientational and translational order parameters, the Helmholtz free energy, and entropy of FSSFs have also been investigated. Reasonable agreement between the theoretically predicted and the experimentally obtained--by means of calorimetric techniques--data on the heat capacity of the partially fluorinated 5-n-alkyl-2-(4-n-(perfluoroalkyl-metheleneoxy)phenyl) (H10F5MOPP) films has been obtained.
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Affiliation(s)
- A V Zakharov
- Saint Petersburg Institute for Machine Sciences, The Russian Academy of Sciences, Saint Petersburg 199178, Russia.
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Veum M, Duelge L, Droske J, Nguyen HT, Huang CC, Mirantsev LV. Comparison between experiment and theory in the temperature variation of film tension above the bulk isotropic transition in free-standing liquid-crystal films. Phys Rev E 2009; 80:031707. [PMID: 19905131 DOI: 10.1103/physreve.80.031707] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2009] [Indexed: 11/07/2022]
Abstract
Using differential scanning calorimetry, the transition enthalpies and temperatures for the bulk smectic-isotropic phase transition have been measured for a series of liquid-crystal compounds. For five compounds, those values were used as parameters in a microscopic mean-field model to predict the temperature dependence of the difference in free-energy density between a sample of material in a free-standing smectic film and that in the bulk. The model predicts a weak temperature dependence below the bulk clearing point and a pronounced monotonic increase with temperature above the transition temperature. The compounds used in this study were chosen specifically because they were also the subject of a previous independent experimental study [M. Veum, Phys. Rev. E 74, 011703 (2006)] that demonstrated a sudden monotonic increase in the free-standing film tension with temperature, which is qualitatively consistent with the predictions of the above-mentioned mean-field model. This study presents a direct and quantitative comparison between the predictions of the mean-field model and the results from previous tension experiments.
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Affiliation(s)
- M Veum
- Department of Physics and Astronomy, University of Wisconsin-Stevens Point, Stevens Point, Wisconsin 55481, USA.
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Kulagin VV, Cherepenin VA, Gulyaev YV, Kornienko VN, Pae KH, Valuev VV, Lee J, Suk H. Characteristics of relativistic electron mirrors generated by an ultrashort nonadiabatic laser pulse from a nanofilm. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2009; 80:016404. [PMID: 19658820 DOI: 10.1103/physreve.80.016404] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2008] [Revised: 04/01/2009] [Indexed: 05/28/2023]
Abstract
For controllable generation of an isolated attosecond relativistic electron bunch [relativistic electron mirror (REM)] with nearly solid-state density, we proposed [V. V. Kulagin, Phys. Rev. Lett. 99, 124801 (2007)] to use a solid nanofilm illuminated normally by an ultraintense femtosecond laser pulse having a sharp rising edge (nonadiabatic laser pulse). In this paper, the REM characteristics are investigated in a regular way for a wide range of parameters. With the help of two-dimensional (2D) particle-in-cell (PIC) simulations, it is shown that, in spite of Coulomb forces, all of the electrons in the laser spot can be synchronously accelerated to ultrarelativistic velocities by the first half-cycle of the field, which has large enough amplitude. For the process of the REM generation, we also verify a self-consistent one-dimensional theory, which we developed earlier (cited above) and which takes into account Coulomb forces, radiation of the electrons, and laser amplitude depletion. This theory shows a good agreement with the results of the 2D PIC simulations. Finally, the scaling of the REM dynamical parameters with the field amplitude and the nanofilm thickness is analyzed.
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Affiliation(s)
- Victor V Kulagin
- Advanced Photonics Research Institute, GIST, Gwangju 500-712, Republic of Korea.
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Canabarro AA, de Oliveira IN, Lyra ML. Homeotropic surface anchoring and the layer-thinning transition in free-standing films. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2008; 77:011704. [PMID: 18351863 DOI: 10.1103/physreve.77.011704] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2007] [Indexed: 05/26/2023]
Abstract
In this work, we investigate the interplay between surface anchoring and finite-size effects on the smectic-isotropic transition in free-standing smectic films. Using an extended McMillan model, we study how a homeotropic anchoring stabilizes the smectic order above the bulk transition temperature. In particular, we determine how the transition temperature depends on the surface ordering and film thickness. We identify a characteristic anchoring for which the transition temperature does not depend on the film thickness. For strong surface ordering, we found that the thickness dependence of the transition temperature can be well represented by a power-law relation. The power-law exponent exhibits a weak dependence on the range of film thicknesses, as well as on the molecular alkyl tail length. Our results reproduce the main experimental findings concerning the layer-thinning transitions in free-standing smectic films.
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Affiliation(s)
- A A Canabarro
- Instituto de Física, Universidade Federal de Alagoas, 57072-970 Maceió, Alagoas, Brazil
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Veum M, Blees MK, Voshell N, Nguyen HT, Huang CC. Role of molecular weight and phase sequence in the temperature variation of film tension above the bulk isotropic transition in freestanding liquid-crystal films. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2006; 74:011703. [PMID: 16907107 DOI: 10.1103/physreve.74.011703] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2006] [Indexed: 05/11/2023]
Abstract
Building upon our previous report [Veum, Phys. Rev. E 17, 020701(R) (2005)] involving two compounds, we have performed a systematic study of the temperature variation of film tension above the bulk isotropic transition in freestanding films to include a total of six smectic liquid-crystal compounds. Consistent with the previous results, the tension increases sharply with temperature above the transition, the tension-temperature slope is proportional to the film's thickness, and the data can be interpreted in the context of theoretical models for layer thinning. Our data suggest that both molecular weight and bulk phase appearing below its isotropic phase play important roles in the slope values.
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Affiliation(s)
- M Veum
- Department of Physics and Astronomy, University of Wisconsin-Stevens Point, Stevens Point, Wisconsin 55481, USA.
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de Oliveira IN, Lyra ML, Mirantsev LV. Temperature dependence of the Casimir-like force in free-standing smectic films. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2006; 73:041703. [PMID: 16711823 DOI: 10.1103/physreve.73.041703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2005] [Indexed: 05/09/2023]
Abstract
The thermal Casimir-like force in free-standing liquid crystal films close to the smectic-A-nematic transition temperature is computed using a quadratic functional approach. In the framework of a microscopic mean-field model of free-standing smectic-A films, the temperature dependence of the order parameter profiles is computed and later used to estimate the elastic coupling variability in the vicinity of first- and second-order bulk smectic-A-nematic phase transitions. The strong nonuniformity of the coupling constant profiles promotes a significant increase of the fluctuation-induced force over three orders of magnitude, especially in thin films. This result reinforces the possible predominance of the thermal Casimir force as compared to the standard van der Waals interaction in thin smectic-A liquid crystal films.
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Affiliation(s)
- I N de Oliveira
- Instituto de Física, Universidade Federal de Alagoas, 57072-970 Maceió-Alagoas, Brazil
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Dolganov PV, Cluzeau P, Joly G, Dolganov VK, Nguyen HT. Interaction of surfaces in smectic membranes and their instability near thinning transitions. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2005; 72:031713. [PMID: 16241466 DOI: 10.1103/physreve.72.031713] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2005] [Indexed: 05/05/2023]
Abstract
We report measurements of the interaction between surfaces of the presmectic membrane above the temperature of transition to the phase without layer ordering. Investigations were performed employing cholesteric droplets embedded in the membrane in the temperature range of thinning transitions. Upon heating, the difference between the membrane tension and surface tension of the bulk sample decreases sufficiently, which leads to membrane instability. After the thinning transition, the membrane returns to a stable state with a larger value of surface interaction.
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Affiliation(s)
- P V Dolganov
- Institute of Solid State Physics, Russian Academy of Sciences, 142432 Chernogolovka, Moscow Region, Russia
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