Dynamics of Solids and Liquids by Neutron Scattering

ISBN-13: 9783642811159 / Angielski / Miękka / 2012 / 382 str.

S. W. Lovesey; T. Springer; R. Comes

Opis

Inelastic neutron scattering is a well established and important technique for studying the dynamical properties of condensed matter at the atomic level. Often, as is the case of experiments designed to study motions of hydrogen atoms, or magnetic excitations, it may yield information obtainable in no other way. Our aim in assembling this book is to produce an overview of some research topics which have come to the fore recently with the development of high neutron fluxes and high performance inelastic scattering spectrometers. The topics dis cussed here are, by and large, developing rapidly and have not reached the stage at which definitive accounts are always possible. Authors have not therefore attempted to make an extensive review of their topic, and the papers quoted in the text are, in general, those which are seen as having been important in its develop ment (they date, roughly, from the 1971 IAEA conference on neutron scattering held in Grenoble). Basic phenomena are illustrated for the most part by the discussion of one, or two, typical examples. The authors hope that the book will be useful to researchers who are not yet fully aware of the diverse range of problems to which the technique can be applied, and to students beginning research work. For this reason, the first chapter by S. w."

Spis treści

1. Introduction.- 1.1 Prologue.- 1.2 Correlation Functions.- 1.3 Nuclear Scattering.- 1.3.1 Scattering by Phonons.- 1.3.2 Phonon Interactions.- 1.3.3 Electron-Phonon Interactions.- 1.3.4 Monoatomic Liquids.- 1.3.5 Molecular Gases.- 1.4 Polarization Effects.- 1.5 Magnetic Scattering.- 1.5.1 Ferromagnetic Spin Waves.- 1.5.2 Antiferromagnetic Spin Waves.- 1.5.3 Paramagnetic Scattering.- Appendix A: Crystal Lattices and Reciprocal Lattices.- References.- 2. Phonons.- 2.1 Lattice Dynamics and Neutron Scattering.- 2.1.1 General Model.- 2.1.2 Rigid-Ion and Shell Models.- 2.1.3 Experimental.- 2.2 Lattice Dynamics of Crystals of the Rutile Type — TiO2, MgF2, and MnF2.- 2.2.1 TiO2.- 2.2.2 MgF2.- 2.2.3 MnF2.- 2.2.4 Conclusions.- 2.3 Phonon Anomalies in Superconducting Materials.- 2.3.1 Transition Metal Carbides.- 2.3.2 A-15 Compounds.- 2.3.3 Niobium-Alloys, Other Compounds, and Impurities.- 2.3.4 Other Superconductors — Tc, Mo-Re, Hg.- 2.3.5 Conclusions.- 2.4 Layered Compounds.- 2.4.1 MoS2.- 2.4.2 NbSe2.- 2.4.3 Graphite.- 2.4.4 PbI2.- 2.4.5 Concluding Remarks.- 2.5 Effects of Pressure on Phonon Spectra.- 2.5.1 Experimental Aspects.- 2.5.2 Phonon Shifts and Widths in Neon.- 2.5.3 Selected Phonons in Rubidium as a Function of Temperature and Volume.- 2.5.4 Conclusions.- References.- 3. Phonons and Structural Phase Transformations.- 3.1 Relation Between Neutron and X-Ray Scattering Techniques.- 3.1.1 Elastic and Inelastic Scattering.- 3.1.2 Experimental Technique.- Inelastic Neutron Scattering.- X-Ray Scattering.- 3.1.3 Correlations and Dimensionality in Real and Reciprocal Space.- 3.2 Fluctuations and Order.- 3.2.1 Soft Modes.- 3.2.2 Critical Slowing Down.- 3.2.3 Eigenvector and Order Parameter.- 3.3 Experimental Results.- 3.3.1 Ferrodistortive Transformations.- 3.3.2 Antiferrodistortive Transformations.- 3.3.3 Modulated Lattices and Low Dimensional Systems.- References.- 4. Dynamics of Molecular Crystals, Polymers, and Adsorbed Species.- 4.1 Molecular Crystals.- 4.1.1 Models for the Lattice Dynamics in Molecular Crystals.- 4.1.2 The Lattice Dynamics of ?-Paradichlorobenzene.- 4.1.3 The Dynamics of Hexamethylenetetramine.- 4.1.4 Incoherent Neutron Scattering, Phonon Density of States, and Intramolecular Vibrations.- 4.1.5 Molecular Torsional Motions and Tunneling Spectroscopy.- 4.1.6 Phonon Density of States Measurements by Optical Spectroscopy.- 4.2 Polymers.- 4.2.1 Polyethylene — the Isolated Chain and Incoherent Scattering Studies.- 4.2.2 Polyoxymethylene.- 4.2.3 Biopolymers.- 4.3 Structure and Dynamics of Adsorbed Species.- 4.3.1 Substrates.- 4.3.2 Physisorption.- 4.3.3 Incoherent Scattering.- 4.4 Chemisorption.- 4.4.1 Hydrocarbons Adsorbed on Zeolites.- 4.4.2 Hydrogen Adsorbed on Metals.- 4.5 Intercalation Compounds.- 4.5.1 Tantalum Disulphide-Ammonia.- 4.5.2 Translational Diffusion in Alumino-Silicate Minerals.- 4.6 Conclusions.- References.- 5. Molecular Rotations, and Diffusion in Solids, in Particular Hydrogen in Metals.- 5.1 Diffusion in Solids, in Particular Hydrogen in Metals.- 5.1.1 General Aspects.- 5.1.2 Experiments on Hydrogen in Pd, a fcc-Lattice.- 5.1.3 Hydrogen in the bcc Metals Ta, Nb, and V.- 5.1.4 The Temperature- and Q-Dependence of the Quasielastic Intensity.- 5.1.5 Conclusions on H-Metal Systems; Other Problems of Diffusion in Solids.- 5.2 Rotations in Molecular Solids.- 5.2.1 Rotations and Hindrance Potential; Scattering Law.- 5.2.2 High Temperatures: Rotational Jumps and Rotational Diffusion.- 5.2.3 Fixed-Window-Method.- 5.2.4 Low Temperature Experiments; Quantum Rotations.- 5.3 Liquids, Liquid Crystals, and Related Problems.- 5.3.1 The Scattering Law for Molecular Liquids.- 5.3.2 Liquid Crystals, Polymers.- References.- 6. Collective Modes in Classical Monoatomic Liquids.- 6.1 Collective Modes.- 6.1.1 Collective Variables.- 6.1.2 Generalized Hydrodynamics.- 6.2 Coherent Scattering.- 6.2.1 Insulating Liquids.- 6.2.2 Liquid Metals.- 6.2.3 Comparison of Systems Studied.- 6.3 Transverse Current Correlations.- 6.4 Relations Between S(Q,?) and Ss(Q,?).- 6.5 Current Issues.- References.- 7. Magnetic Scattering.- 7.1 Magnons in Ionic Compounds.- 7.2 Quasi One- and Two-Dimensional Systems.- 7.2.1 Magnetic Linear-Chain Systems.- 7.2.2 Layered Magnetic Systems.- 7.3 Magnons in Metals.- 7.4 Crystal Field Levels in Rare Earth Compounds.- 7.5 Magnons and Excitons in Rare Earth Metals.- 7.6 Critical Magnetic Scattering.- 7.7 Hyperfine Field Measurements.- References.