Browsing by Author "Pan, LiDong"

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Surface-induced ordering effect in one antiferroelectric liquid crystal compound
(2009-03-01)
Pan, LiDong
;
Wang, Shun
;
Hsu, C. S.
;
Huang, C. C.
;
應用化學系
Null transmission ellipsometer was employed to study the surface-induced tilt transition of an antiferroelectric liquid crystal compound in the bulk smectic-A (SmA) temperature range. The data of the surface tilt transition can be fitted with an extended mean-field model. These results indicate the transition is near a mean-field tricritical point. The surface layers' tilt directions are found to be in different planes several degrees above the bulk SmA-SmC alpha* transition.
Surface-Surface Interaction in Smectic Liquid Crystal Films
(2012-01-11)
Pan, LiDong
;
Hsu, C. S.
;
Huang, C. C.
;
應用化學系
;
Department of Applied Chemistry
Null transmission ellipsometry was employed to study the field induced transition of the surface arrangements in freestanding films of smectic liquid crystals. The interlayer interaction between the two surfaces obtained from the threshold voltage for the transition is found to be antiferroelectric and is quasilong ranged. The possible microscopic origins of the measured interaction and its relevance to the interlayer interaction in antiferroelectric liquid crystal materials are discussed.
Thickness Dependent Phase Behavior of Antiferroelectric Liquid Crystal Films
(2009-10-30)
Pan, LiDong
;
Wang, Shun
;
Hsu, C. S.
;
Huang, C. C.
;
應用化學系
Free standing films of a liquid crystal compound with simple surface enhanced order were studied. The resultant phase diagram demonstrates that (1) the short helical pitch smectic-C-alpha* phase disappears below a film thickness of 10 layers, and (2) the temperature window of a distorted 4 layer smectic-C-FI2* phase increases dramatically upon decreasing film thickness. The experimental findings were attributed to the reduced dimensionality and enhanced surface effects in thin films. The results of the smectic-C-alpha* phase are consistent with what have been reported for helically ordered magnetic thin films, with a noticeable difference due to the opposite effect of the surface on ordering in the two systems.