Molecular orientational properties of a high-tilt chiral smectic liquid crystal determined from its infrared dichroism
Citation:
Sigarev, A.A., Vij, J.K., Hall, A.W., Cowling, S.J., Goodby, J.W. , Molecular orientational properties of a high-tilt chiral smectic liquid crystal determined from its infrared dichroism , Physical Review E - Statistical, Nonlinear, and Soft Matter Physics, 76, 5, 2007, 051707Download Item:
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Abstract:
The orientational characterisitics and the temperature dependencies of the molecular apparent tilt angle of a partly fluorinated chiral smectic liquid crystal (/S/)-4-(1-methylheptyloxycarbonyl)phenyl 4-[6-(3,4,4,4-tetrafluoro-3-trifluoromethylbutylcarbonyloxy)hexyloxy] biphenyl-4-carboxylate (acronym MHPHFHHOBC) are studied using the polarized Fourier transform infrared (FTIR) spectroscopy. The molecular orientational distributions and the orientational order parameters for a homogeneously aligned liquid crystalline sample at various temperatures and external electric fields are examined. The analysis uses the dichroic parameters of the phenyl and the carbonyl bands. For a temperature range of 65?80 ?C corresponding to the antiferroelectric SmCA* phase, the molecular apparent tilt angle lies within the range 43??44?; antiferroelectric smectic structure being rather close to the orthoconic SmCA* phase. An application of sufficiently high dc field across the cell in its SmA* phase surprisingly shows that the dichroism first increases slowly and then rapidly in two stages and finally a saturated apparent tilt angle of ~30? is reached. The IR dichroic data is used to estimate the polar angles and the degree of rotational biasing of the carbonyl groups with respect to the molecular long axis. In the SmA* phase, the sample appears to demonstrate some of the typical properties of a de Vries material.
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Science Foundation Ireland (SFI)
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http://people.tcd.ie/jvijDescription:
PUBLISHEDArticle number 051707 13 pp
Author: VIJ, JAGDISH
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Journal ArticleSeries/Report no:
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics76
5
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Electronic & Electrical EngineeringDOI:
http://dx.doi.org/10.1103/PhysRevE.76.051707Licences: