Orientational order parameter of two cyano nematogens by optical spectroscopy

Refractive index and density measurements of two cyano nematogens, namely p-hexyloxybenzylidene p-aminobenzonitrile and p-octyloxybenzylidene p-aminobenzonitrile have been carried out. From these data, orientational order parameter S has been estimated using different methods. Principal polarizabili...

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Bibliographic Details
Published in:Phase transitions 2016-05, Vol.89 (5), p.514-522
Main Authors: Vinutha, N., Pardhasaradhi, P., Usha, M.K., Revannasiddaiah, D.
Format: Article
Language:English
Subjects:
Anisotropy
birefringence
crossover temperature
Crossovers
density
Extrapolation
Nematic
Optical properties
Order parameters
orientational order parameter
Phase transitions
Refractive index
Refractivity
Schiff's base compounds
Spectrum analysis
Vibration
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Summary:Refractive index and density measurements of two cyano nematogens, namely p-hexyloxybenzylidene p-aminobenzonitrile and p-octyloxybenzylidene p-aminobenzonitrile have been carried out. From these data, orientational order parameter S has been estimated using different methods. Principal polarizabilities have been calculated using the well-known Vuks isotropic and Neugebauer anisotropic models. Polarizability anisotropy has been estimated using Lippincott δ-function, molecular vibration, Haller's extrapolation and Vuks scaling methods. Using these values, the orientational order parameter S has been estimated at different temperatures in their nematic phases. The values obtained have been compared and discussed. Further, using the experimental refractive index data, the nematic crossover temperatures have also been estimated for these compounds.
ISSN:0141-1594
1029-0338
DOI:10.1080/01411594.2015.1102256