Orientational order in nematic, smectic A, and smectic C phases of doped with dichroic dye§

§ This article is dedicated to Prof. Jerzy A. Janik on his 80th birthday.

Abstract

The long-range orientational order of mesogenic 4-n-pentylphenylthio-4′-n-octyloxybenzoate () doped with a dichroic dye was studied by means of electronic absorption and fluorescence measurements. The order parameters ⟨P₂ ⟩ and ⟨P₄ ⟩ as well as the orientational distribution function were determined on the basis of absorption and emission spectra of linearly polarized light recorded as a function of temperature in the nematic, smectic A and smectic C phases. An influence of the dye molecular structure on the orientational order of the dye/liquid crystal mixture was observed. A correlation between the order parameter values and the phase transitions temperature shift due to the dye addition was found.

§ This article is dedicated to Prof. Jerzy A. Janik on his 80th birthday.

Keywords:

• Thermotropic liquid crystal
• Dichroic dye
• Orientational order
• Phase transition
• Light absorption and emission

Acknowledgements

This work was supported by Poznań University of Technology Research Project No. TB 64-001/2006-DS.

Notes

§ This article is dedicated to Prof. Jerzy A. Janik on his 80th birthday.