Download or read book NMR Studies of Liquid Crystal nonliquid Crystal Mixtures written by David Francis Hillenbrand and published by . This book was released on 1974 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nuclear Magnetic Resonance of Liquid Crystals written by Ronald Y. Dong and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt: Intended for researchers and students in physics, chemistry and materials science, this book provides the necessary background information and sufficient mathematical and physical detail to study the current research literature. The book begins with a survey of liquid crystal phases and field effects, together with an introduction to the basic physics of nuclear magnetic resonance. It then discusses orientational ordering and molecular field theories for various liquid crystal molecules and nmr studies of uniaxial and biaxial phases. Subsequent chapters consider spin relaxation processes and rotational, translational, and internal molecular dynamics of liquid crystals. The final chapter discusses two-dimensional and multiple- quantum nmr spectroscopies and their application in elucidating liquid crystal properties. This second edition, updated throughout, incorporates many new references and includes new mathematical appendices.
Download or read book NMR Studies of Liquid Crystals and Molecules Dissolved in Liquid Crystal Solvents written by Gary Drobny and published by . This book was released on 1982 with total page 648 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book NMR of Liquid Crystal Dendrimers written by Carlos Rodrigues da Cruz and published by CRC Press. This book was released on 2016-12-08 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dendrimers are hyperbranched molecules with well-defined nanometer-scale dimensions. Important technological applications of these systems, both in biomedicine and materials science, have been recently proposed. Liquid crystal dendrimers are fascinating materials that combine the characteristics of dendrimers with the anisotropic physical behaviour and molecular self-organization typical of liquid crystals. This unique association of physical and chemical properties, together with the possibility of multi-selective functionalization put forward by dendrimers, opens new perspectives for applications. Nuclear magnetic resonance (NMR) is a powerful experimental technique applied in materials science and an important tool to the study of molecular organization and dynamics. This book presents an introduction to dendrimers properties with special insight into liquid crystal dendrimers and a detailed description of the NMR theory and experimental techniques used in the investigation of these materials. It also discusses recent NMR research results on liquid crystal dendrimers, with emphasis on molecular order and dynamics studies. This book introduces the properties of dendrimers, with special insight into liquid crystal dendrimers, and a detailed description of NMR theory and experimental techniques used in the investigation of these materials. It also discusses results of recent NMR research on liquid crystal dendrimers, with an emphasis on molecular order and dynamics studies. Advanced undergraduate and graduate students of physics, chemistry, and materials science and researchers in the fields of dendrimers, liquid crystals, and NMR will find the book extremely useful.
Download or read book A 2H NMR Study of the Motion of the Liquid Crystal Mixtures of 7S5 and 8S5 in the Nematic Phase written by Brian Lynn Peko and published by . This book was released on 1993 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Carbon 13 NMR Studies of Liquid Crystals written by Stuart Anthony Allison and published by . This book was released on 1976 with total page 270 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book NMR of Liquid Crystal Dendrimers written by Carlos R. Cruz and published by Jenny Stanford Publishing. This book was released on 2016-12-05 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dendrimers are hyperbranched molecules with well-defined nanometer-scale dimensions. Important technological applications of these systems, both in biomedicine and materials science, have been recently proposed. This book presents an introduction to dendrimers properties with special insight into liquid crystal dendrimers and a detailed description of the NMR theory and experimental techniques used in the investigation of these materials. It also discusses recent NMR research results on liquid crystal dendrimers, with emphasis on molecular order and dynamics studies.
Download or read book Carbon 13 NMR Studies of Liquid Crystals written by and published by . This book was released on 1975 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt: High resolution, proton decoupled 13C nmr are observed for a series of neat nematic liquid crystals, the p-alkoxyazoxybenzenes, and a smectic-A liquid crystal, diethylazoxydibenzoate in a magnetic field of 23 kG. The (uniaxial) order parameters S = P2(cos[theta]) are found to be about 0.4 and 0.9 for the nematic and smectic-A phase respectively at the clearing points. The order parameter increases with decreasing temperature in the nematic phase but is constant, or nearly so, with temperature in the smectic-A phase. In the nematic series studied, the ordering exhibits an even-odd alternation along the series and qualitative agreement with a recent theory due to Marcelja is found. In both phases, the spectra show that the molecule rotates rapidly about its long axis. Tentative conclusions about molecular conformational motion and 14N spin relaxation are presented for both nematic and smectic-A phases. In the smectic-A phase, the sample is rotated about an axis perpendicular to H0 and the resulting spectra are discussed. The theory of observed chemical shifts in liquid crystals is treated in an appendix. Equations are derived which relate the nmr spectra of liquid-crystals to the order parameters. A model for the smectic-C phase due to Luz and Meiboom and Doane is described and lineshapes are determined on the basis of this model for special cases. Experiments on smectic-C liquid crystals are currently underway for comparison with the theory. Also treated in an appendix is the dependence of the order parameters on the molecular potential which give rise to the various degrees of order in the different liquid crystalline phases. To a good approximation the functional dependence of the order parameters on the molecular potential is shown to be a simple one in the limit of small tilt angle in the smectic-C phase.
Download or read book NMR Studies of Small Molecules in Liquid Crystalline Solutions written by Hyung Jin Park and published by . This book was released on 2005 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Liquid Crystals and Ordered Fluids written by Julian F. Johnson and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 481 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains papers presented at the Second Symposium on Ordered Fluids and Liquid Crystals held at the 158th National Meeting of the American Chemical Society, New York, Sep tember, 1969. The Symposium was sponsored by the Division of Colloid and Surface Chemistry. The proceedings for the first symposium on this subject were published by the American Chemical Society in the Advances in Chemistry Series. In the preface to the volume for the first meet ing held four years ago, we noted that research on liquid crystals had gone through tremendous fluctuations, with peaks of activity around 1900 and again in the early 1930's. The present period of high activity which started about 1960 has continued to exhibit acceleration. The reason for the persistent growth in the field is due to the increasing recognition of the important role played by liquid crystals in both biological systems and in items of commerce as diverse as detergents and electronic components. Addi tionally, more powerful and sophisticated instrumentation is pro viding a basis for understanding the properties of the liquid crystalline state as weIl as yielding inc~s~ve tests for the theories of mesophase structure which are only now reaching astate of maturity. Julian F. Johnson Roger S. Porter v CONTENTS Thermal Phase Transitions in Biomembranes • . • • • • • . • • 1 Joseph M. Steim Conditions of Stability for Liquid-Crystalline Phospholipid Membranes .
Download or read book NMR Studies of Liquid Crystals and Molecules Dissolved in Liquid Crystal Solvents written by and published by . This book was released on 1982 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book NMR Studies of Molecules in Liquid Crystals and Graphite written by Mark Edward Rosen and published by . This book was released on 1992 with total page 388 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Liquid Crystals and Ordered Fluids written by Anselm C. Griffin and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 1133 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume represents a collection of selected papers presented at a symposium of the same name sponsored by the Division of Colloid and Surface Chemistry held at the national Spring meeting of the American Chemical Society in Las Vegas, Nevada, March 29 - April 1, 1982. Also included are invited papers from a number of outstanding overseas liquid crystal scientists who were unable to attend the symposium. The attendance at the symposium itself and the number of papers contained herein is reflective of the high level of current interest in (and maturity of) the field of liquid crystal research. Included in this volume are papers mainly derived from the fields of chemistry and physics ranging in content from the design and synthesis of new meso genic materials to theoretical physical treatments of anisotropic liquids. One of the significant aspects of current liquid crystal research is the increasing col laboration between chemist and phys.icist. The overlap of these two areas has been growing over the last several years and many contri butions to this volume involve a molecular approach to the chemical physics of liquid crystalline materials.
Download or read book Chemical Physics and the Condensed Phase written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Liquid crystals are an excellent media for the study of the condensed phase by NMR spectroscopy since the highly accurate proton dipolar couplings do not average to zero as they do in the isotropic condensed phase. Of course we can also take the opposite view and seek to understand the behavior of individual molecules and the effect of the condensed phase on them and so the impetus for studies of solutes in liquid crystals is two fold. By coupling theory to experiment via dipolar couplings one can gain insight into aspects of chemical physics and the condensed phase provided the spectra can be solved. As the number of spins of a molecule and its lack of symmetry increase so do the complexity of NMR spectra of solutes in orientationally ordered phases. Covariance Matrix Adaptation Evolutionary Strategies (CMA-ES) have proven to be remarkably useful towards the end of obtaining dipolar couplings from congested spectra. In essence this algorithm uses the principles of natural selection coupled with an aspect of cross-generational memory to find the set of spectral parameters at the global minima of an error surface which reproduce the experimental spectrum. It is not an overstatement to say this tool has significantly altered the allocation of efforts in the area of research presented here. In the research herein two approaches are employed which are complimentary. In the first chapters we use a diversity of solutes to test postulated interaction Hamiltonians intended to describe the intermolecular environment of nematic and smectic A phases. The putative Hamiltonians are fitted to solute order parameters obtained from dipolar couplings. Once an explicit form is obtained, reasonable speculation is made concerning what the Hamiltonian can tell us about the intermolecular environment of the condensed phases studied. In the latter chapters the complimentary view is taken. Specifically we attempt to understand how internal rotations of molecules are affected by the condens.
Download or read book Multiple quantum NMR Studies of Spin Clusters in Liquid Crystals and Zeolites written by John Gilbert Pearson and published by . This book was released on 1991 with total page 354 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nuclear Magnetic Resonance of Liquid Crystals written by Ronald Y. Dong and published by Springer. This book was released on 2012-03-19 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt: Liquid crystals have become ubiquitous in the displays for electronic devices, ranging from wrist watches to laptop computers. Nuclear magnetic resonance is one of the important mechanisms for determining their structures tures and properties. This book covers NMR techniques used in studying liquid crystals and present up to date results from such studies. Ronald Dong has worked on NMR in liquid crystals for much of his professional career. Topics covered include: Nuclear spin dynamics, orientational order, molecular field theories of liquid-crystal molecules, nuclear spin relaxation, spin relaxation, rotational and translational dynamics, internal dynamics of liquid-crystal molecules, NMR in liquid crystals; an appendix covers rotations, Euler angles and Wigner rotation matrices.
Download or read book Biaxial Nematic Liquid Crystals written by Geoffrey R. Luckhurst and published by John Wiley & Sons. This book was released on 2015-03-27 with total page 430 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the nematic liquid crystal phase, rod-shaped molecules move randomly but remain essentially parallel to one another. Biaxial nematics, which were first predicted in 1970 by Marvin Freiser, have their molecules differentially oriented along two axes. They have the potential to create displays with fast switching times and may have applications in thin-film displays and other liquid crystal technologies. This book is the first to be concerned solely with biaxial nematic liquid crystals, both lyotropic and thermotropic, formed by low molar mass as well as polymeric systems. It opens with a general introduction to the biaxial nematic phase and covers: • Order parameters and distribution functions • Molecular field theory • Theories for hard biaxial particles • Computer simulation of biaxial nematics • Alignment of the phase • Display applications • Characterisation and identification • Lyotropic, thermotropic and colloidal systems together with material design With a consistent, coherent and pedagogical approach, this book brings together theory, simulations and experimental studies; it includes contributions from some of the leading figures in the field. It is relevant to students and researchers as well as to industry professionals working in soft matter, liquid crystals, liquid crystal devices and their applications throughout materials science, chemistry, physics, mathematics and display engineering.
