X-Ray Diffraction Study of Nematic Smectic A and C Liquid Crystals PDF Download
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Author: B. I. Ostrovskii Publisher: CRC Press ISBN: 9783718649075 Category : Science Languages : en Pages : 76
Book Description
Reviews recent studies of X-ray scattering phenomena in liquid crystals, in particular their relationship to phase-transition physics. Also explored are the main approximations which are used to obtain structural information from the scattering spectre of liquid crystals and to determine the short-range order in the molecule arrangement.
Author: B. I. Ostrovskii Publisher: CRC Press ISBN: 9783718649075 Category : Science Languages : en Pages : 76
Book Description
Reviews recent studies of X-ray scattering phenomena in liquid crystals, in particular their relationship to phase-transition physics. Also explored are the main approximations which are used to obtain structural information from the scattering spectre of liquid crystals and to determine the short-range order in the molecule arrangement.
Author: P. G. de Gennes Publisher: Oxford University Press ISBN: 9780198517856 Category : Science Languages : en Pages : 620
Book Description
This new edition of the classic text incorporates the many advances in knowledge about liquid crystals that have taken place since its initial publication in 1974. Entirely new chapters describe the types and properties of liquid crystals in terms of both recently discovered phases and current insight into the nature of local order and isotropic-to-nematic transition. There is an extensive discussion of the symmetrical, macroscopic, dynamic, and defective properties of smectics and columnar phases, with emphasis on order-of-magnitude considerations, all illustrated with numerous descriptions of experimental arrangements. The final chapter is devoted to phase transitions in smectics, including the celebrated analogy between smectic A and superconductors. This new version's topicality and breadth of coverage will ensure that it remains an indispensable guide for researchers and graduate students in mechanics and engineering, and in chemical, solid state, and statistical physics.
Author: D.M.P. Mingos Publisher: Springer ISBN: 3540681183 Category : Technology & Engineering Languages : en Pages : 276
Book Description
The liquid crystalline state may be identified as a distinct and unique state of matter which is characterised by properties which resembles those of both solids and liquids. It was first recognised in the middle of the last century through the study of nerve myelin and derivatives of cholesterol. The research in the area really gathered momentum, however, when as a result of the pioneering work of Gray in the early 1970's organic compounds showing liquid crystalline properties were shown to be suitable to form the basis of display devices in the electronic products. The study of liquid crystals is truly multidisciplinary and has attached the attention of physicists, biologists, chemists, mathematicians and electronics engineers. It is therefore impossible to cover all these aspects fully in two small volumes and therefore it was decided in view of the overall title of the series to concentrate on the structural and bonding aspects of the subject. The Chapters presented in these two volumes have been organised to cover the following fundamental aspects of the subject. The calculation of the structures of liquid crystals, an account of their dynamical properties and a discussion of computer simulations of liquid crystalline phases formed by Gay Berne mesogens. The relationships between molecular conformation and packing are analysed in some detail. The crystal structures of liquid crystal mesogens and the importance of their X ray scattering properties for characterisational purposes are discussed.
Author: Publisher: ISBN: Category : Languages : en Pages : 324
Book Description
This thesis describes several studies in which nuclear magnetic resonance (nmr) spectroscopy has been used to probe the structure, orientation and dynamics of liquid crystal mesogens and molecules dissolved in liquid crystalline phases. In addition, a modern high field nmr spectrometer is described which has been used to perform such nmr studies. Chapter 1 introduces the quantum mechanical formalisms used throughout this thesis and briefly reviews the fundamentals of nuclear spin physics and pulsed nmr spectroscopy. First the density operator is described and a specific form for the canonical ensemble is derived. Then Clebsch-Gordon coefficients, Wigner rotation matrices, and irreducible tensor operators are reviewed. An expression for the equilibrium (Curie) magnetization is obtained and the linear response of a spin system to a strong pulsed r.f. irradiation is described. Finally, the spin interaction Hamiltonians relevant to this work are reviewed together with their truncated forms. Chapter 2 is a deuterium magnetic resonance study of two 'nom' liquid crystals which possess several low temperature mesomorphic phases. Specifically, deuterium quadrupolar echo spectroscopy is used to determine the orientation of the liquid crystal molecules in smectic phases, the changes in molecular orientation and motion that occur at smectic-smectic phase transitions, and the order of the phase transitions. For both compounds, the phase sequence is determined to be isotropic, nematic, smectic A, smectic C, smectic B{sub A}, smectic B{sub C}, and crystalline. The structure of the smectic A phase is found to be consistent with the well-known model of a two dimensional liquid in which molecules are rapidly rotating about their long axes and oriented at right angles to the plane of the layers. Molecules in the smectic C phase are found to have their long axes tilted with respect to the layer normal, and the tilt angle is temperature dependent, increasing from zero at the smectic A - smectic C transition and reaching a maximum at 9{sup o} at the smectic C - smectic B{sub A} transition. This finding contradicts the results of X-ray diffraction studies which indicate that the tilt angle is 18{sup o} and temperature independent. The smectic B{sub A} - smectic B{sub C} phase transition is observed for the first time, and is found to be first order, a result that contradicts the prediction of a mean theory by McMillian. Chapter 3 is a multiple quantum nmr study of n-hexane oriented in a nematic liquid crystal solvent. The basic three pulse multiple quantum experiment is discussed which enables the observation of transitions for which.
Author: Patrick Oswald Publisher: CRC Press ISBN: 9780849398407 Category : Science Languages : en Pages : 724
Book Description
Liquid crystals allow us to perform experiments that provide insight into fundamental problems of modern physics, such as phase transitions, frustration, elasticity, hydrodynamics, defects, growth phenomena, and optics. Smectic and Columnar Liquid Crystals: Concepts and Physical Properties Illustrated by Experiments is a result of personal research and of the graduate lectures given by the authors at the École Normale Supérieure de Lyon and the University of Paris VII, respectively. The book examines lamellar (smectic) and columnar liquid crystals, which, in addition to orientational order, possess 1D, 2D or 3D positional order. This volume illustrates original physical concepts using methodically numerous experiments, theoretical developments, and diagrams. Topics include rheology and plasticity, ferroelectricity, analogies with superconductors, hexatic order and 2D-melting, equilibrium shapes, facetting, and the Mullins-Sekerka instability, as well as phase transitions in free films and membrane vibrations. Nematic and cholesteric liquid crystals are covered by the authors in a separate volume entitled Nematic and Cholesteric Liquid Crystals: Concepts and Physical Properties Illustrated by Experiments. Smectic and Columnar Liquid Crystals is an ideal introduction and a valuable source of reference for theoretical and experimental studies of advanced students and researchers in liquid crystals, condensed matter physics, and materials science.
Author: B. I. Ostrovskii
Author: B. I. Ostrovskii
Author: Zengqiang Liu
Author: P. G. de Gennes
Author: D.M.P. Mingos
Author: Pilla Ackley Leitner
Author: Andrew Nickolas Cady
Author: J. Als- Nielsen
Author: 
Author: Patrick Oswald
Author: Satyen Kumar