Download Free A Field Cycling Nmr Relaxometry Study On Molecular Liquids And Plastically Crystalline Phases Book in PDF and EPUB Free Download. You can read online A Field Cycling Nmr Relaxometry Study On Molecular Liquids And Plastically Crystalline Phases and write the review.

Field-cycling NMR relaxometry is evolving into a methodology of widespread interest with recent technological developments resulting in powerful and versatile commercial instruments. Polymers, liquid crystals, biomaterials, porous media, tissue, cement and many other materials of practical importance can be studied using this technique. This book summarises the expertise of leading scientists in the area and the editor is well placed, after four decades of working in this field, to ensure a broad ranging and high quality title. Starting with an overview of the basic principles of the technique and the scope of its use, the content then develops to look at theory, instrumentation, practical limitations and applications in different systems. Newcomers to the field will find this book invaluable for successful use of the technique. Researchers already in academic and industrial settings, interested in molecular dynamics and magnetic resonance, will discover an important addition to the literature.
This book discusses the application of nuclear magnetic relaxometry in the wide-line regime, to probe molecular processes in soft materials like liquid crystals in their bulk and confined forms. The focus is on slow dynamics, exclusively detected via dispersion of the associated spectral densities extracted from low-frequency spin-lattice relaxation rates. The first two chapters provide the theoretical basis for appreciation of nuclear spin relaxation rate measurements as a handle to characterize specific dynamics in liquid crystals, and their implementation over several decades of Larmor frequency employing recent methods like field-cycling NMR technique. The subsequent chapters discuss new results so obtained on certain chosen liquid crystal systems. The findings of these investigations are summarized in the last chapter, critically evaluating the exclusive scope and applicability of field-cycling based relaxometry to probe interesting, and novel, slow dynamics in these systems.
Molecular reorientation and translation in molecular liquids was studied. A dominant premise in these studies was that, except in strongly hydrogen-bonded systems such as water, the dynamics of a liquid may be considered to be a series of impulsive collisions. Details of the behavior would be dominated by the shape and size of the molecules under constant packing conditions. The second area of effort was in the plastic crystalline solid phase of two globular molecules, adamantane and cyclohexane. The NMR technique was used in these studies to measure self-diffusion coefficients and spin-lattice relaxation times. The applicability of pulsed NMR techniques to the study of the kinetics of order--disorder phase transitions in solid adamantane was demonstrated.
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.
Edited by one of the leading experts in the field, this handbook emphasizes why solid-state issues are important, which approaches should be taken to avoid problems and exploit the opportunities offered by solid state properties in the pharmaceutical and agricultural industries. With its practical approach, this is at once a guideline for development chemists just entering the field as well as a high-quality source of reference material for specialists in the pharmaceutical and chemical industry, structural chemists, physicochemists, crystallographers, inorganic chemists, and patent departments.
Dynamics of Soft Matter: Neutron Applications provides an overview of neutron scattering techniques that measure temporal and spatial correlations simultaneously, at the microscopic and/or mesoscopic scale. These techniques offer answers to new questions arising at the interface of physics, chemistry, and biology. Knowledge of the dynamics at these levels is crucial to understanding the soft matter field, which includes colloids, polymers, membranes, biological macromolecules, foams, emulsions towards biological & biomimetic systems, and phenomena involving wetting, friction, adhesion, or microfluidics. Emphasizing the complementarities of scattering techniques with other spectroscopic ones, this volume also highlights the potential gain in combining techniques such as rheology, NMR, light scattering, dielectric spectroscopy, as well as synchrotron radiation experiments. Key areas covered include polymer science, biological materials, complex fluids and surface science.
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.
On March 26-27, 1980, a symposium organized by one of us (P. P. ) was held at the l79th American Chemical Society National ~1eeting in Houston, Texas, under the sponsorship of the Theoretical Chemistry Subdivision of the Division of Physical Chemistry. The symposium was entitled "The Role of the Electrostatic Potential in Chemistry," and it served as a stimulus for this book. The original scope and coverage have been broadened, however; included here, in addition to contributions from the eleven invited symposium speakers and two of the poster-session participants, are four papers that were specially invited for this book. Furthermore, several authors have taken this opportunity to present at least partial reviews of the areas being discussed. Most of the manuscripts were completed in the late spring and early summer of 1980. We hope that this book will achieve two goals: First, we are trying to provide an overall picture, including recent advances, of current chemical research, both fundamental and applied, involving the electrostatic potential. Second, we want to convey an appreci ation of both the powers and also the limitations of the electro static potential approach. In order to achieve these goals, we have selected contributors whose research areas provide a very broad coverage of the field. Throughout the book, we have used a. u.