Effect of enantiomeric excess on surface structures and phase sequences in free-standing liquid-crystal films.
نویسندگان
چکیده
We present differential optical reflectivity and null transmission ellipsometry data from several mixtures of MHPBC enantiomers. From this data, we have determined the chiral smectic phase sequence as a function of enantiomeric excess. The data suggest a change in the structure of the smectic-C(*)(alpha) phase and the surface tilt state as the enantiomeric excess is reduced. The results also show that the intermediate phases, smectic C(*)(FI2), smectic C(*)(FI1), and smectic C(*)(alpha), disappear sequentially on reducing the net chirality.
منابع مشابه
Role of electrostatics in the texture of islands in free-standing ferroelectric liquid crystal films.
Curved textures of ferroelectric smectic-C* liquid crystals produce space charge when they involve divergence of the spontaneous polarization field. Impurity ions can partially screen this space charge, reducing long-range interactions to local ones. Through studies of the textures of islands on very thin free-standing smectic films, we see evidence of this effect, in which materials with a lar...
متن کاملTextural transformations in islands on free standing smectic-C* liquid crystal films.
We report on and analyze the textural transformations in islands, thicker circular domains, floating in very thin free standing chiral Smectic-C* liquid crystal films. As an island is growing, an initial pure bend texture of the director changes into a reversing spiral at a critical size. Another distinct spiral texture is induced by changing the boundary condition at the central point defect i...
متن کاملTemperature Tunability of Dielectric/ Liquid Crystal / Dielectric Photonic Crystal Structures
Recently, photonic crystals doped with liquid crystal (LC) material havegained much research interest. In this article new ternary one-dimensional photoniccrystal introduced and studied. The liquid crystal layer of 5CB and 5PCH is sandwichedby two dielectric layers. For the first time, we use four structures SiO2/UCF35/CaF2,SiO2/5CB/CaF2, NFK51/UCF35/NPSK53 and NFK51/5CB/NPSK53. The effect ofte...
متن کاملReentrant synclinic phase in an electric-field-temperature-phase diagram for enantiomeric mixtures of an antiferroelectric liquid crystal.
The threshold electric field E(th) for a transition from the anticlinic to the synclinic phase of enantiomeric mixtures of the liquid crystal TFMHPOBC was measured as a function of temperature T and enantiomeric excess X. For small X the phase boundary curve on a temperature-electric-field phase diagram exhibits the phase sequence synclinic-anticlinic-reentrant synclinic on decreasing the tempe...
متن کاملSurface Effects on Phases Transitions in Smectic Membranes
In liquid crystal materials, frustration between competing interactions and thermal fluctuation results in the observation of many different phases (up to 5) in a relatively narrow temperature window (usually about 30K). Identifying the interactions as well as finding out the nature of those interactions that stabilize those phases is a very important and interesting question. In this thesis, w...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Physical review. E, Statistical, nonlinear, and soft matter physics
دوره 66 6 Pt 1 شماره
صفحات -
تاریخ انتشار 2002