X-ray studies of the surface and bulk structure of the isotropic and nematic phase of a lyotropic liquid crystal

Journal Article · Sat Jun 15 04:00:00 EDT 1991 · Physical Review, A; (USA)

DOI:https://doi.org/10.1103/PhysRevA.43.6815· OSTI ID:5662807

Swislow, G; Schwartz, D; Ocko, B M; Pershan, P S ^[1]; Litster, J D ^[2]

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1. Department of Physics and the Division of Applied Science, Harvard University, Cambridge, Massachusetts 02138 (US)
2. Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (US)

We have used x-ray specular reflection to study the structure of the air--liquid-crystal interface of the lyotropic liquid crystal formed from binary mixtures of cesium perfluoro-octanoate (CsPFO) and water. In the isotropic phase the surface is coated with a monolayer of CsPFO separated by layers of water from one or more smectic bilayers of CsPFO. As for the case of thermotropic liquid crystals, the isotropic-to-nematic phase transition has no effect on the surface structure, and as the temperature is lowered towards the nematic--to--smectic-{ital A} transition temperature, the number of surface-induced smectic layers increases dramatically (e.g., approximately 100 layers were observed). Theoretical modeling of the reflectivity excludes the possibility that the surface bilayers are arrays of micelles. X-ray scattering from critical smectic short-range order in the bulk, studied by tuning the spectrometer away from the specular condition, indicates that the scattering is fundamentally different from short-range smectic order in thermotropic systems.

• DOE Contract Number: AC02-76CH00016
• OSTI ID: 5662807
• Journal Information: Physical Review, A; (USA), Journal Name: Physical Review, A; (USA) Vol. 43:12; ISSN 1050-2947; ISSN PLRAA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360602* -- Other Materials-- Structure & Phase Studies
360603 -- Materials-- Properties
ALKALI METAL COMPOUNDS
CESIUM COMPOUNDS
CRYSTALS
ELECTROMAGNETIC RADIATION
FLUIDS
IONIZING RADIATIONS
LIGHT SCATTERING
LIQUID CRYSTALS
LIQUIDS
OPTICAL PROPERTIES
PHASE STUDIES
PHYSICAL PROPERTIES
RADIATIONS
REFLECTIVITY
SCATTERING
SURFACE PROPERTIES
X RADIATION