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Novotna V.,ASCR Institute of Physics Prague | Hamplova V.,ASCR Institute of Physics Prague | Sasnouski G.,Institute of Applied Physics Problems | Salamon P.,Hungarian Academy of Sciences
Liquid Crystals | Year: 2016

New lactic acid derivatives, based on terphenyl molecular core laterally substituted by chlorine atom, have been synthesised and their liquid crystalline properties studied. We varied the molecular structure by prolonging the non-chiral chain and analysed the mesogenic properties with respect to its length. We found that all new compounds reveal the SmA*–SmC* phase sequence in an extremely broad temperature interval. The experimental techniques, namely the polarising optical microscopy, differential scanning calorimetry, x-ray diffraction and helical pitch measurements, have been applied to establish the physical properties. Studied compounds exhibit very high values of the spontaneous polarisation and the tilt angle grows continuously on cooling up to 42°. The pitch values drop down when prolonging the molecular non-chiral chain. © 2016 Informa UK Limited, trading as Taylor & Francis Group

Chivel Yu.A.,Institute of Applied Physics Problems
Journal of Optical Technology (A Translation of Opticheskii Zhurnal) | Year: 2011

The influence of the state of the target surface on the processes of near-surface plasma formation is studied in a wide range of wavelengths and laser-radiation pulse widths. These experiments made it possible to reveal the local character of the initial ablation of the target surface, caused both by surface defects and by the defects that appeared at an early stage of the action of the pulsed laser radiation because of the volume heterogeneity of solids. It is shown that the localness of the breakdown affects the evolution of the near-surface plasma formation. The differences in the character of the formation of the near-surface plasma are revealed when short pulses with rapidly increasing laser-radiation intensity act and when laser pulses with a slowly increasing leading edge act. It is established that the localness of the breakdown affects the evolution of the Rayleigh-Taylor hydrodynamic instability of the contact surface between the target vapor and subsequently the plasma and the gas surrounding the target, compressed by the leading shock wave. © 2011 Optical Society of America.

Lapanik V.,Institute of Applied Physics Problems | Bezborodov V.,Belarusian State Technological University | Sasnouski G.,Institute of Applied Physics Problems | Haase W.,TU Darmstadt
Liquid Crystals | Year: 2013

The storage of information after mechanical stimuli even without applied electrical field is based on the elastic properties of the ferroelectric liquid crystal (FLC) material and the anchoring energy. It is favourable for chiral molecules with extended length, such as 4,4′-di-substituted quaterphenyls and 4,4′-di-substituted quinquephenyls, which have in series-connected benzene rings, but not separated by bridging fragments. To obtain the required stability with a reasonable switching speed of about 50 μs 4,4′-di-substituted chiral quaterphenyls with two chiral centres on the same wing has been synthesised. Here, the switching is much faster compared to compounds with same quaterphenyl fragment, but only with one chiral centre. © 2013 Copyright Taylor & Francis.

Lapanik V.,Institute of Applied Physics Problems | Bezborodov V.,Institute of Applied Physics Problems | Timofeev S.,Institute of Applied Physics Problems | Haase W.,TU Darmstadt
Applied Physics Letters | Year: 2010

Shock-free ferroelectric liquid crystal displays with high optical contrast and low operating voltage are the concern of this contribution. Ferroelectric liquid crystal compositions with a wide temperature range of the chiral smectic C phase are designed. The influence of the chiral fragments of the molecules, especially their length, on the mechanical stability of the SmC phase has been investigated. The relation between the surface anchoring energy of the aligning polymer and the viscoelastic properties of the SmC phase has been described. Our qualitative model reflects the resistance of the SmC layer structure against mechanical and thermal action. © 2010 American Institute of Physics.

Lapanik V.,Institute of Applied Physics Problems | Bezborodov V.,Institute of Applied Physics Problems | Sasnouski G.,Institute of Applied Physics Problems | Haase W.,TU Darmstadt
Phase Transitions | Year: 2012

The effect of the molecular structure of liquid crystals on their mesomorphic and physico-chemical properties is studied. The unique compounds described in this work contain three or four phenyl rings. Modifications of the molecules via bridge fragments or via lateral substituents allowed the preparation and optimization of specific mixtures for different purposes. The formation of defect-free layers in ferroelectric liquid crystals (FLCs) stable against various mechanical or temperature deformations is studied. The impact of viscous-elastic and chiral properties on the formation of smectic C* layers were established. A new electro-optic effect based on chiral-nematic mixtures for creating high-speed devices with switching time less than 1ms was developed. All the boundary conditions necessary for the realization of this effect were experimentally investigated. © 2012 Copyright Taylor and Francis Group, LLC.

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