Influence of the light-induced molecular transformations on the helix pitch and lasing spectra of cholesteric liquid crystals

2004 ◽  
Author(s):  
Igor P. Ilchishin ◽  
Oleg V. Yaroshchuk ◽  
Sergiy V. Gryshchenko ◽  
Eugene A. Shaydiuk
Keyword(s):  
Liquid Crystals ◽  
Cholesteric Liquid Crystals ◽  
Helix Pitch

Notizen: Bestimmung des Helixdrehsinnes cholesterischer Phasen mit der Grandjean-Cano-Methode / Determination of the Helical Sense of Cholesteric Liquid Crystals Using the Grandjean-Cano Method

1977 ◽  
Vol 32 (8) ◽  
pp. 899-902 ◽  
Author(s):  
G. Heppke ◽  
F. Oestreicher
Keyword(s):  
Molecular Structure ◽  
Liquid Crystals ◽  
Nematic Phase ◽  
Ring System ◽  
Cholesteric Liquid Crystals ◽  
Cholesteric Phase ◽  
Chiral Compounds ◽  
Helix Pitch

Abstract A simple way of determining the helix screw sense of a cholesteric phase using the Grandjean-Cano method is described. The helix pitch as well as its sense is investigated for ten cholesteric phases, induced by mesogenic chiral com­pounds in the nematic isomere mixture of 4-methoxy-4′-n-butylazoxybenzene (Nematic Phase 4, Merck). For the chiral compounds with nematic-like molecular structure it is found that the screw sense alternates with the number of bonds between the chiral centre and the ring system.

Rotatable Diffraction Gratings Based on Cholesteric Liquid Crystals with Phototunable Helix Pitch

2015 ◽  
Vol 3 (9) ◽  
pp. 1273-1279 ◽  
Author(s):  
Alexander Ryabchun ◽  
Alexey Bobrovsky ◽  
Joachim Stumpe ◽  
Valery Shibaev
Keyword(s):  
Liquid Crystals ◽  
Diffraction Gratings ◽  
Cholesteric Liquid Crystals ◽  
Helix Pitch

scholarly journals Synthesis and Characterization of Novel Bio-Chiral Dopants Obtained from Bio-Betulin Produced by a Fermentation Process

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 785
Author(s):  
Veridiana G. Guimarães ◽  
Anastasiia Svanidze ◽  
Tianyi Guo ◽  
Pawan Nepal ◽  
Robert J. Twieg ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Natural Product ◽  
Fermentation Process ◽  
Synthesis And Characterization ◽  
Cholesteric Liquid Crystals ◽  
And Performance ◽  
Chiral Dopants

Cholesteric liquid crystals are frequently produced by the addition of chiral dopants to achiral nematic hosts. We report here the synthesis and performance of chiral dopants obtained from bio-betulin produced by a fermentation process. An important aspect of this work is to point out that the fermentation process used to obtain the starting materials is much easier and cheaper when carried out in large volumes than isolating it from the natural product. The performance of the dopants obtained from bio-betulin is indistinguishable from those obtained from commercially available synthetic betulin.

scholarly journals Augmented Lagrangian preconditioners for the Oseen–Frank model of nematic and cholesteric liquid crystals

2021 ◽  
Author(s):  
Jingmin Xia ◽  
Patrick E. Farrell ◽  
Florian Wechsung
Keyword(s):  
Liquid Crystals ◽  
Augmented Lagrangian ◽  
Augmented Lagrangian Method ◽  
Mass Matrix ◽  
Unit Length ◽  
Mesh Size ◽  
Schur Complement ◽  
Cholesteric Liquid Crystals ◽  
Multigrid Algorithm ◽  
The Cost

AbstractWe propose a robust and efficient augmented Lagrangian-type preconditioner for solving linearizations of the Oseen–Frank model arising in nematic and cholesteric liquid crystals. By applying the augmented Lagrangian method, the Schur complement of the director block can be better approximated by the weighted mass matrix of the Lagrange multiplier, at the cost of making the augmented director block harder to solve. In order to solve the augmented director block, we develop a robust multigrid algorithm which includes an additive Schwarz relaxation that captures a pointwise version of the kernel of the semi-definite term. Furthermore, we prove that the augmented Lagrangian term improves the discrete enforcement of the unit-length constraint. Numerical experiments verify the efficiency of the algorithm and its robustness with respect to problem-related parameters (Frank constants and cholesteric pitch) and the mesh size.

scholarly journals Pitch tuning induced by optical torque in heliconical cholesteric liquid crystals

2019 ◽  
Vol 1 (3) ◽  
Author(s):  
G. Nava ◽  
F. Ciciulla ◽  
O. S. Iadlovska ◽  
O. D. Lavrentovich ◽  
F. Simoni ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Cholesteric Liquid Crystals ◽  
Optical Torque

scholarly journals Light-driven rotation of gratings formed by electroconvection patterns in cholesteric liquid crystals

2021 ◽  
pp. 116366
Author(s):  
Ying Xiang ◽  
Hongzhen Jing ◽  
Hao Chen ◽  
Jun zhang ◽  
Xiaoyu Ding ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Cholesteric Liquid Crystals

scholarly journals Optical Response Associated with the Orientation and Structure of Liquid Crystals with Respect to Phosphatidylcholine Concentration

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 678
Author(s):  
Yuqi Han ◽  
Yan Jiang ◽  
Wei Guo ◽  
Bing Li ◽  
Lu Zhang ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Reflectance Spectrum ◽  
Optical Response ◽  
The Self ◽  
Cholesteric Liquid Crystals ◽  
Anchoring Effect ◽  
Self Assembling ◽  
Sensitization Effect ◽  
Structure Of Liquid

Based on the anchoring effect due to the self-assembling behavior of the phospholipid molecules at the interface between the liquid crystal and water phases on the orientation of liquid crystals, the optical response associated with the orientation and structure of liquid crystals with respect to the concentration of 1,2-didodecanoyl-sn-glycero-3-phosphocholine solution has been investigated. The optical response owing to changes in the orientation and structure of the mixed cholesteric liquid crystals with respect to the change in the concentration of phosphatidylcholine has been obtained. Moreover, the feasibility of using as-prepared mixed cholesteric liquid crystals to measure the phosphatidylcholine concentration has been verified. A methodology to measure the reflectance spectrum by using mixed cholesteric liquid crystals to sensitize the phosphatidylcholine concentration has been further realized. The sensitization effect of the mixed cholesteric liquid crystals on the measurement of phosphatidylcholine concentration was also verified.

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