The Order Parameters of Some Nematic Liquid Crystals Measured by the Resonance Raman Effect and Its Relevance to the Nematic-Isotropic Phase Transition

1981 ◽  
Vol 66 (1) ◽  
pp. 67-74 ◽  
Author(s):  
Shunsuke Kobinata ◽  
Yuko Nakajima ◽  
Hiroshi Yoshida ◽  
Shiro Maeda
Keyword(s):  
Phase Transition ◽  
Liquid Crystals ◽  
Raman Effect ◽  
Nematic Liquid Crystals ◽  
Resonance Raman ◽  
Order Parameters ◽  
Isotropic Phase

Laser Beam Induces Reorientation in Nematic Liquid Crystals

2010 ◽  
Vol 428-429 ◽  
pp. 224-227
Author(s):  
I Min Jiang ◽  
Yu Jen Chen ◽  
Wen Chi Hung ◽  
C.T. Kuo ◽  
D.J. Jang ◽  
...  
Keyword(s):  
Phase Transition ◽  
Liquid Crystals ◽  
Laser Beam ◽  
Nematic Liquid Crystals ◽  
Beam Propagation ◽  
Isotropic Phase ◽  
Optical Alignment ◽  
Optically Induced

Nematic liquid crystals (NLCs) can be easily reoriented by the laser beam at the temperature closed to the nematic–isotropic phase transition (TNI). At the temperature closed to TNI, the propagating mode of laser beam and the optically induced phase transition were explored by using a microscopic conoscope technique. This investigation demonstrates the formation of soliton at particular beam propagation modes. The interaction between nematic liquid crystals and the laser beam with different polarizations showed the nonlinearity in optical alignment.

scholarly journals Emergence and stabilization of transient twisted defect structures in confined achiral liquid crystals at a phase transition.

Soft Matter ◽  
2021 ◽  
Author(s):  
Jose X Velez ◽  
Zhaofei Zheng ◽  
Daniel A. Beller ◽  
Francesca Serra
Keyword(s):  
Phase Transition ◽  
Liquid Crystals ◽  
Soft Matter ◽  
Capillary Tube ◽  
Nematic Liquid Crystals ◽  
Defect Structures

Spontaneous emergence of chirality is a pervasive theme in soft matter. We report a transient twist forming in achiral nematic liquid crystals confined to a capillary tube with square cross...

scholarly journals Order Parameters, Orientational Distribution Functions and Heliconical Tilt Angles of Oligomeric Liquid Crystals

2019 ◽  
Author(s):  
Richard Mandle ◽  
John W. Goodby
Keyword(s):  
Phase Transition ◽  
Liquid Crystals ◽  
Tilt Angle ◽  
Order Parameter ◽  
Nematic Phase ◽  
Liquid Crystalline ◽  
Thermal Evolution ◽  
Order Parameters ◽  
Distribution Functions ◽  
Orientational Distribution

We compare the order parameters, orientational distribution functions (ODF) and heliconical tilt angles of the TB phase exhibited by a liquid-crystalline dimer (CB7CB) to a tetramer (O47) and hexamer (O67) by SAXS/WAXS. Following the N-TB phase transition we find that all order parameters decrease, and while 〈P2 〉 remains positive 〈P4 〉 becomes negative. For all three materials the order parameter 〈P6 〉 is near zero in both phases. The ODF is sugarloaf-like in the nematic phase and volcano-like in the TB phase, allowing us to estimate the heliconical tilt angle of each material and its thermal evolution. The heliconical tilt angle appears to be largely independent of the material studied despite the differing number of mesogenic units.

Molecular Ordering in Nematic MBCA and EPAPU

1990 ◽  
Vol 45 (1) ◽  
pp. 29-32
Author(s):  
S. Sreehari Sastry ◽  
V. Venkata Rao ◽  
P. Narayana Murty ◽  
G. Satyanandam ◽  
T. F. Sundar Raj
Keyword(s):  
Phase Transition ◽  
Liquid Crystals ◽  
Order Parameter ◽  
Nematic Phase ◽  
Spin Probe ◽  
Nematic Liquid Crystals ◽  
Experimental Techniques ◽  
First Order ◽  
Molecular Ordering

AbstractBy EPR, two nematic liquid crystals (MBCA and EPAPU) were investigated using a steroidal nitroxide spin probe. In both liquid crystals the isotropic-nematic phase transition is of first order. The observed variation of the order parameter with temperature is compared with predictions from the Maier-Saupe and Humphries-James-Luckhurst models and with results obtained by several other experimental techniques.

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