scholarly journals Experimental Verification of Vuks Equation Using Hollow Prism Refractometer

2012 ◽  
Vol 2012 ◽  
pp. 1-6
Author(s):  
Anita Kanwar ◽  
Priya S. Yadav
Keyword(s):  
Liquid Crystal ◽  
Temperature Dependence ◽  
Experimental Verification ◽  
Cholesteric Liquid Crystal ◽  
Visible Range ◽  
Refractive Indices ◽  
Temperature Dependent ◽  
Crystalline Materials ◽  
Different Temperatures ◽  
Molecular Polarizabilities

The refractive indices of the cholesteric liquid crystal solution were measured using multiwavelength (visible range) refractometer for three different wavelengths. Measurements were made at different temperatures for various concentrations of the solution, mixing CLC in a soluble solvent. Vuks equation describes the wavelength and temperature dependence of refractive indices of anisotropic crystalline materials. We have used a simplified version of Vuks equation relating only to macroscopic indices and verified its validity for five-different-concentration solution at various temperatures. The result is also used to obtain molecular polarizabilities and temperature dependent material constants of our sample.

scholarly journals The temperature dependence of the helical pitch in a cholesteric liquid crystal

2021 ◽  
pp. e1881638
Author(s):  
Robert A. Skutnik ◽  
Jan-Christoph Eichler ◽  
Marco G. Mazza ◽  
Martin Schoen
Keyword(s):  
Liquid Crystal ◽  
Temperature Dependence ◽  
Cholesteric Liquid Crystal ◽  
Helical Pitch

Position-Sensitive Cholesteric Liquid Crystal Dye Laser Covering a Full Visible Range

2007 ◽  
Vol 46 (No. 36) ◽  
pp. L874-L876 ◽  
Author(s):  
Koji Sonoyama ◽  
Yoichi Takanishi ◽  
Ken Ishikawa ◽  
Hideo Takezoe
Keyword(s):  
Liquid Crystal ◽  
Cholesteric Liquid Crystal ◽  
Dye Laser ◽  
Visible Range ◽  
Position Sensitive

STUDY OF MOLECULAR MOTIONS IN TWO LIQUID CRYSTAL FORMING COMPOUNDS EMPLOYING PLS

2006 ◽  
Vol 20 (14) ◽  
pp. 2019-2034 ◽  
Author(s):  
K. CHANDRAMANI SINGH ◽  
M. SHARMA ◽  
P. C. JAIN
Keyword(s):  
Liquid Crystal ◽  
Temperature Dependence ◽  
Liquid Crystalline ◽  
Positron Lifetime ◽  
Strong Temperature Dependence ◽  
Molecular Motions ◽  
Temperature Dependent ◽  
Slow Cooling ◽  
Positron Lifetime Spectroscopy ◽  
Motion Studies

Results of molecular motion studies carried out in two liquid crystal forming compounds n-p-cyano-p-hexyloxybiphenyl (M18) and n-p-ethoxybenzylidene-p-butylaniline (EBBA) using positron lifetime spectroscopy (PLS) are presented. Temperature dependent positron lifetime measurements have been performed in each compound during the heating cycle of samples prepared by either quenching or slow cooling from the respective liquid crystalline phase of the compounds. In both the compounds, behaviors of the quenched and slow cooled samples are found to be different. The material in the quenched sample, unlike the slow-cooled sample, exhibits strong temperature dependence before it undergoes a glass transition. In each case, the temperature dependence of o-Ps pick-off lifetime in the quenched sample shows broad peaks at various characteristic temperatures. These peaks have been attributed to various intra- and inter-molecular motions associated with these compounds. The characteristic frequencies of some of the modes observed in the present work agree well with the literature reported values obtained from FIR and Raman studies. The present study demonstrates the usefulness of PLS in the study of molecular motions.

Synthesis and Characterization of a Cholesteric Liquid Crystal Cholesteryl Nonanoate

2010 ◽  
Vol 428-429 ◽  
pp. 94-97 ◽  
Author(s):  
Yuan Ming Huang ◽  
Ye Tang Guo ◽  
Qing Lan Ma ◽  
Wei Wei Liu
Keyword(s):  
Liquid Crystal ◽  
Cholesteric Liquid Crystal ◽  
Synthesis And Characterization ◽  
Temperature Dependent ◽  
Scanning Calorimetry ◽  
Selective Reflection ◽  
Cholesteric Phase ◽  
Polarized Optical Microscopy ◽  
Clearing Point

A cholesteric liquid crystal cholesteryl nonanoate was synthesized and then characterized by means of differential scanning calorimetry and polarized optical microscopy. As temperature decreased from its clearing point, cholesteric phase was formed for cholesteryl nonanoate and accompanied by continuous evolution of colors in the focal conic textures. Furthermore, beautiful spherulite crystals were observed to grow out of the cholesteric phase as the crystallization continued. The evolution of the colors in recorded textures was contributed to temperature-dependent selective reflection of the liquid crystal.

Temperature dependent color cone lasing in cholesteric liquid crystal

2013 ◽  
Author(s):  
Po-Yen Chen ◽  
Kuan-Cheng Liao ◽  
Ja-Hon Lin ◽  
Yao-Hui Chen ◽  
Shwu-Yun Tsay Tzeng ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Cholesteric Liquid Crystal ◽  
Temperature Dependent

Investigation of the Temperature Dependence of the Pitch of a Cholesteric Liquid Crystal

1976 ◽  
Vol 35 (1-2) ◽  
pp. 135-142 ◽  
Author(s):  
Sadao Masubuchi ◽  
Tadashi Akahane ◽  
Kazuhira Nakao ◽  
Toshiharu Tako
Keyword(s):  
Liquid Crystal ◽  
Temperature Dependence ◽  
Cholesteric Liquid Crystal

ORDER PARAMETER FROM (p-ETHOXYBENZYLIDENE-)-p-n-BUTYLANILINE CHANNELED SPECTRA

2001 ◽  
Vol 15 (25) ◽  
pp. 1131-1139
Author(s):  
MARGARETA SOCACIU ◽  
MARCELA URSACHE ◽  
EMIL PETRESCU ◽  
GABRIELA IACOBESCU
Keyword(s):  
Data Processing ◽  
Temperature Dependence ◽  
Local Field ◽  
Order Parameter ◽  
Computation Time ◽  
Processing Method ◽  
Refractive Indices ◽  
Experimental Setup ◽  
Data Processing Method ◽  
Different Temperatures

The dispersion of refractive indices and birefringence of EBBA were determined at different temperatures and the band contributions to these dependencies were computed. An improved Talbot–Rayleigh experimental setup was used and, in order to increase the accuracy and minimize the computation time, a new data processing method was proposed. The temperature dependence of the order parameter and of the correction factor g, originating from the anisotropy of the local field, were computed.

Temperature-dependent chirality of cholesteric liquid crystal for terahertz waves

2020 ◽  
Vol 45 (18) ◽  
pp. 4988
Author(s):  
Xin Zhang ◽  
Fei Fan ◽  
Yun-Yun Ji ◽  
Sheng-Jiang Chang
Keyword(s):  
Liquid Crystal ◽  
Cholesteric Liquid Crystal ◽  
Terahertz Waves ◽  
Temperature Dependent

Circadian Rhythm of Locomotion and its Temperature Dependence in Blattella Germanica

1971 ◽  
Vol 54 (1) ◽  
pp. 187-198
Author(s):  
HANS DREISIG ◽  
ERIK TETENS NIELSEN
Keyword(s):  
Circadian Rhythm ◽  
Light Intensity ◽  
Temperature Dependence ◽  
Blattella Germanica ◽  
Temperature Dependent ◽  
Continuous Darkness ◽  
Expected Time ◽  
Different Temperatures ◽  
Free Running ◽  
Increasing Temperature

1. The activity in Blattella germanica was investigated under standard conditions. Periods of latency and increment were recognized. 2. The free-running rhythm in continuous darkness was determined at different temperatures and showed about the same period. The free-running rhythm in continous light could not be determined unless the light intensity was extremely low. 3. The period of activity was not released immediately after a change from light to darkness if this was advanced in relation to the normal time. The activity was then only slightly advanced. 4. Delay of the onset of darkness caused the activity to diminish gradually after the usual time of change from light to dark. 5. If the temperature was lowered some time before the expected time of activity in continuous darkness the activity was advanced much more than normally. If the temperature was raised the activity was delayed. 6. Based upon these and other studies, a theory is advanced which explains the activity rhythms in insects as being the result of the interaction between a gradually increasing, temperature-dependent sensitization and different thresholds of release determined by light and temperature. A theory is propounded concerning the temperature-independence of the free-running rhythm in continuous darkness, assuming a temperature-dependent threshold of release.

scholarly journals PHOTOTUNABLE SELECTIVE REFLECTION OF CHOLESTERIC LIQUID CRYSTALS

Doklady BGUIR ◽  
2019 ◽  
pp. 28-31
Author(s):  
D. S. Chepeleva ◽  
A. S. Yakovleva ◽  
A. A. Murauski ◽  
I. N. Kukhta ◽  
A. A. Muravsky
Keyword(s):  
Liquid Crystal ◽  
Cholesteric Liquid Crystal ◽  
Emission Spectra ◽  
Spectral Shift ◽  
Visible Range ◽  
Trans Form ◽  
Selective Reflection ◽  
Maximum Displacement ◽  
Reflection Peak ◽  
Equilibrium Ratio

The dependence of the helical pitch of a cholesteric liquid crystal based on a composite photosensitive chiral dopant (cChD) on the intensity of light irradiation was studied. The transmission spectra and the selective reflection spectra of cholesteric liquid crystal cells were measured. The concentration of the cChD additive is calculated, so that the peak of selective reflection and its rearrangement occurs in the visible range of the electromagnetic radiation spectrum (380-780 nm). The possibility of photo-control by shifting the peak of the selective reflection of the cChD additive was studied, when exposed to LEDs with wavelengths of 365 nm and 450 nm, while reducing or increasing the intensity, a change in the spiral pitch was observed. Depending on the light intensity, part of the molecules of the chiral additive containing the azo group underwent isomerization, i.e. molecules in the trans-form passed to the cis-form, which led to a spectral shift of the selective reflection peak. If a small intensity of the 365 nm LED was applied, then some of the molecules were forced to transition from the trans- to the cis-form, and then, when illuminated with a 450 nm LED, from the cisto the trans-form. After reversible rearrangement, the properties of cholesteric liquid crystal changes due to interaction with light, because under the influence of light, the equilibrium ratio of the trans- and cis-isomers of the molecules of the substance changed, which macroscopically changed the torsion force of the chiral additive. Using two LEDs of 365 nm and 450 nm with different emission spectra, a reversible control of the cChD selective reflection peak in the visible range was obtained. The maximum displacement occurred at approximately 145 nm.

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