scholarly journals Probing a Local Viscosity Change at the Nematic-Isotropic Liquid Crystal Phase Transition by a Ratiometric Flapping Fluorophore

2021 ◽  
Author(s):  
Ryo Kimura ◽  
Hidetsugu Kitakado ◽  
Takuya Yamakado ◽  
Hiroyuki Yoshida ◽  
Shohei Saito
Keyword(s):  
Phase Transition ◽  
Liquid Crystal ◽  
Isotropic Phase ◽  
Molecular Rotor ◽  
Isotropic Liquid ◽  
Viscosity Change ◽  
Thermal Phase Transition ◽  
Crystal Phase Transition ◽  
Liquid Crystal Phase Transition ◽  
Liquid Crystal 5Cb

Local viscosity change in the thermal phase transition of a nematic liquid crystal, 5CB, has been analyzed by doping fluorescent viscosity probes, flapping fluorophores (FLAP) as well as a molecular rotor BODIPY-C12. As a result, only flapping anthraceneimide has successfully monitored a small viscosity change (corresponding to a few cP (centipoise) change in shear viscosity around 25 cP) in the nematic-to-isotropic phase transition by ratiometric spectroscopy. In addition, analysis of fluorescence anisotropy indicates that the emissive species (planarized flapping anthraceneimides) are aligned parallel to the director of 5CB in the nematic phase.

Probing a Microviscosity Change at the Nematic-Isotropic Liquid Crystal Phase Transition by a Ratiometric Flapping Fluorophore

2022 ◽  
Author(s):  
Ryo Kimura ◽  
Hidetsugu Kitakado ◽  
Takuya Yamakado ◽  
Hiroyuki Yoshida ◽  
Shohei Saito
Keyword(s):  
Phase Transition ◽  
Liquid Crystal ◽  
Condensed Matter ◽  
Crystal Phase ◽  
Soft Condensed Matter ◽  
Liquid Crystal Phase ◽  
Isotropic Liquid ◽  
Crystal Phase Transition ◽  
Liquid Crystal Phase Transition

Understanding the microviscosity of soft condensed matter is important to clarify the mechanisms of chemical, physical or biological events occurring at the nanoscale. Here, we report that flapping fluorophores (FLAP)...

Evidence for a liquid crystal phase transition in two-dimensional electrons in high Landau levels

2002 ◽  
Vol 12 (9) ◽  
pp. 377-380
Author(s):  
K. B. Cooper ◽  
M. P. Lilly ◽  
J. P. Eisenstein ◽  
L. N. Pfeiffer ◽  
K. W. West
Keyword(s):  
Phase Transition ◽  
Liquid Crystal ◽  
Landau Levels ◽  
Crystal Phase ◽  
Two Dimensional ◽  
Liquid Crystal Phase ◽  
Stripe Phase ◽  
Stripe Order ◽  
Crystal Phase Transition ◽  
Liquid Crystal Phase Transition

Transport measurements of high-mohility two-dimensional electron systems at low temperatures have revealed a large resistance anisotropy around half-filling of excited Landau levels. These results have been attributed to electronic stripe-phase formation with spontaneously broken orientational symmetry. Mechanisms which are known to break the orientational symmetry include poorly-understood crystal structure effects and an in-plane magnetic field, $B_{||}$. Here we report that a large $B_{||}$ also causes the transport anisotropy to persist up to much higher temperatures. In this regime, we find that the anisotropic resistance scales sublinearly with $B_{||}/T$. These observations support the proposal that the transition from anisotropic to isotropic transport reflects a liquid crystal phase transition where local stripe order persists even in the isotropic regime.

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